My AP Biology Thoughts  

Unit #: 8

Welcome to My AP Biology Thoughts podcast, our names are Ramit Dasika, Flavio D’Attilio, Samy Leroux, Landon Schafer, Colin Fahmy and we are hosting this episode called Unit 8 Ecology AND  Today we will be discussing The war between Ukraine and Russia has caused mass destruction to many ecosystems through bombings and other weaponry and how it relates to the AP Biology Curriculum. 

Segment 1: Overview of Topic

•  War 
• The war between Ukraine and Russia has caused mass destruction to many ecosystems through bombings and other weaponry
• 
  

Segment 2: Evidence that supports 

• It causes forest fires- Samy
• During the process of runoff, the harmful chemicals are collected in rivers nearby. This causes the  water sources contaminated due to chemical leakage from destroyed industrial plants-Ramit
• During the Russia-Ukrainian War, the Russian soldiers damaged and looted fire engines, computers, and radiation monitoring equipment, while leaving mines and munitions spread across the exclusion zone.-Flavio
• “In the Donbas region, wrecked sewage works gush their contents into rivers and damaged pipelines fill wetlands with oil.”- Landon
• “Most of the exclusion zone was damaged by the invasion and may be contaminated with unexploded ordnance and mines,” according to Oleksandr Galushchenko, director of the biosphere reserve. The larger mammals that constantly move around the reserve – wolves, deer, brown bears, lynx, elk, and recently reintroduced bison – are at particular risk, he says.”-Samy
• “The forests in the zone remain a radioactive tinderbox that, in the event of fires, could send radioactive isotopes on the winds towards Kyiv. The risks of that happening are now much greater, says the UNCG’s forest campaigner Yehor Hrynyk. With fire-fighting equipment looted and much of the exclusion zone dangerous for firefighters to enter, some 65,000 acres has burned since the invasion, and fires continue to smolder in underground peat.”-Colin
• “Many industrial plants are damaged or abandoned;wrecked sewage works gush their contents into rivers; damaged pipelines are filling wetlands with oil; and toxic military scrap is spread across the land.”- Flavio
• “A particular concern is the many coal mines abandoned after 2014. With pumping of water halted, they have so far released some 650,000 acre-feet of polluted mine water into the environment,...

My AP Biology Thoughts  

Unit #: 8- Disruptions to Ecosystems

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Jaiden: Welcome to My AP Biology Thoughts podcast, our names are Jaiden, Adam, and Reena and we are your hosts for this episode called Unit 8, Human Stupidity and Single Use Plastics. Today we will be discussing how single use plastics cause disruptions to the ecosystem and how it relates to the AP Biology Curriculum. 

The Podcast will be broken up into three segments. The first segment will show the general overview of single-use plastics and the second segment will show how these plastics impact the environment and why it relates to the AP Biology Curriculum. Finally, segment three will discuss how we can contribute and reduce single use plastics.

Segment 1: Overview of Topic

• Plastic pollution has become one of the most pressing environmental issues
• According to the Environmental Protection Agency, Americans generated 35.7 million tons of plastic in the United States. 
• Single use plastics are plastics that are used for a brief period of time, before they are thrown away. These include plastic straws, spoons, bottles, and bags
• Microplastics are extremely small pieces of plastic debris. They are generally about five millimeters, or approximately the diameter  an eraser on a #2 pencils,  in length to be considered microplastics

Segment 2: Just how much harm is plastic causing 

• Some plastics such as Chlorinated plastics is harmful for the soil around it along with water sources making it harder for organisms to grow
• It takes 1,000 years for a plastic bag to degrade in a landfill. However, the plastic does not degrade completely but instead becomes microplastics that absorb toxins and continue to pollute the environment.
• An estimated 13 million plastic tons are thrown into the ocean each 
• These small plastic particles may harm our health once they have entered our bodies. Plastic products contain chemical additives. A number of these chemicals have been associated with serious health problems such as hormone-related cancers, infertility and neurodevelopmental disorders like ADHD and autism.
• There are now 5.25 trillion macro and micro pieces, weighing up to 269,000 tonnes. This is because every day, around 8 million pieces of plastic make their way into our oceans.
• Unlike some other kinds of waste, plastic doesn't decompose. That means plastic can stick around indefinitely, wreaking havoc on marine ecosystems. Some plastics float once they enter the ocean, though...

Welcome to My AP Biology Thoughts podcast, our names are Celine, Xavier, and Sofie and we are your hosts for this episode called Unit 7 Natural Selection: Examples of Evolution-Toxic River Fish. In episode 120, we will be discussing the Toxic River Fish and how it relates to the AP Biology Curriculum. 

We want to thank our sources for the information presented in this podcast episode today which include national geographic and NPR. You can find the citations and links to these sources in the show notes.

• To begin with the overview, the species of fish we will be discussing today are the tomcod
• This species of fish lives in the waters of New Jersey and New York, usually found in the Hudson River where pollutants and chemicals such as polychlorinated biphenyl was dumped between 1947-1976 by General Electric companies
• Therefore they developed a gene the resulted in an immunity

• We can see the evolution of Toxic River fish from the molecular Evolution that was changing in DNA sequences. 
• When the pollutants entered the hudson river it resulted in 95% of the fish developing liver tumors.
• The toxins from the electric company entered the nucleus of cells and For some fish it caused a distortion of DNA instructions. This would cause some to most of the fish in the river to get sick and die.
• By chance, the Toxic River Fish had a version of that gene that tolerated the PCB and toxins
• The toxic river fish evolved to handle dangerous chemicals that were dumped in the river and Overtime the toxic river fish that had the resistant gene did better than the fish without it
• Technically they’re not mutants, but the chemicals did give one genetic group an advantage over the others
• This is where survival of the fittest played a role, the fish that could resist toxins would have a higher rate of survival than those without out resistance 
• The ability to resist the toxins caused the toxic river fish to lose some ability to cope with natural stressors like low oxygen or abnormally high temperatures but they still had advantage above other fish

• Biology is the study of biotic organisms, and focuses on the dynamic and behavior. Evolution is 1/12 characteristics of biology.
• It connects to the course because it distinctly shows evolution through natural selection

Welcome to My AP Biology Thoughts podcast, my name is Chloe and I am your host for episode 30 called Unit 8 Ecology: Simpson Diversity Index.  Today we will be discussing how diversity in an ecosystem can be measured mathematically on a scale from 0 to 1.

• The Simpson Diversity Index measures the diversity in a habitat while taking into account the number of species present and the abundance of organisms in each species. There is a simple equation to this Index which will give you a number from 0 to 1 as your answer, 1 being infinite diversity, and 0 being no diversity at all. 

• The Simpson Diversity Index is important because it can help measure how diversity changes in response to a natural event or human impact. For example, scientists could measure the diversity of a habitat before and after a forest fire, and analyze the Simpson Diversity index to understand how the diversity was affected by the fire. Biodiversity in a habitat is important because each species has a specific role, and a significant decrease in the number of species could have a detrimental effect on the habitat. Keystone species are especially important to a habitat because a majority of species rely and depend on them. If the keystone species gets wiped out, it is more than likely for the Simpson Diversity index to drastically decrease.

• When natural selection results in adaptive radiation, the Simpson diversity index can change drastically. For example, Darwin’s Finches created 13 different species which is an increase in the biodiversity of the ecosystem. Another example is extinction. When a natural disaster causes the diversity index to decrease, many niches are left unoccupied, and the habitat can fall apart leading to extinction. 

Thank you for listening to this episode of My AP Biology Thoughts.   For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.  See you next time!

• "Ice Flow" Kevin MacLeod (incompetech.com)
• Licensed under Creative Commons: By Attribution 4.0 License
•  http://creativecommons.org/licenses/by/4.0/

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Welcome to My AP Biology Thoughts podcast, my name is Nikki and I am your host for episode #29 called Unit 8 Ecology: Symbiotic Relationships..  Today we will be discussing the 3 symbiotic relationships in nature.

• Symbiosis is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasitic. The organisms, each termed a symbiont, may be of the same or of different species

• Mutualism: 2 organisms benefit from one another
• Example:  oxpecker (a kind of bird) and the rhinoceros or zebra. Oxpeckers land on rhinos or zebras and eat ticks and other parasites that live on their skin. The oxpeckers get food and the beasts get pest control. 
• Commensalism: 1 organism benefits and other organism is not impacted
• Example :Remora fish have a disk on their heads that makes them able to attach to larger animals, such as sharks, mantas, and whales. When the larger animal feeds, the remora detaches itself to eat the extra food.
• Parasitism: 1 organism benefits and the other is negatively impacted
• Example: Moose and ticks-In such numbers the ticks drain so much blood that the host moose can become anemic and malnourished 

How does this topic fit into the greater picture of ecology?

• Ecology is all about organisms relationships with each other and the environment
• Helps classify how they all fit in with each other
• because they are a major driving force of evolution- coevolution-evolve together. This networking and cooperation among species allows them to survive better than they would as individuals.

Thank you for listening to this episode of My AP Biology Thoughts.   For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.  See you next time!

• "Ice Flow" Kevin MacLeod (incompetech.com)
• Licensed under Creative Commons: By Attribution 4.0 License
•  http://creativecommons.org/licenses/by/4.0/

• Apple Podcasts
• Spotify
• Google Podcasts  
• Stitcher  
• YouTube  

Welcome to My AP Biology Thoughts podcast, my name is Morgan and I am your host for episode #28 called Unit 8 Ecology: Density Independent vs Density Dependent limiting factors..  Today we will be discussing exactly that, limiting factors in an ecosystem that are considered density independent and density dependent.

Population density- the number of organisms within a given area or ecosystem (how crowded)

Low density ecosystems- organisms spread out (country/rural)

High density ecosystems- lots of organisms in little space (New York City)

Organisms can't grow exponentially or else the earth would be covered in all sorts of animals and population, so we need something that limits the population

Limiting Factor- something in an ecosystem that helps contain a population’s size by slowing or stopping growth, (biotic or abiotic)

Density dependent factors- higher the density of the population, the higher the impact of the limiting factor will be. When there are more organisms, more will be affected

Density independent- regardless of the density (crowdedness/ number of organisms) the limiting factor will decrease the population the same amount. 

• large population and small population would be equally impacted

What are these limiting factors?

Density dependent factors are food, shelter, water, parasites, and predators. 

• There is competition for these resources so in a larger population, more animals are competing for these factors, and more animals will NOT have access to them
• A smaller population has less competition, and will not suffer as much from this lack of resources. 

The same goes for parasites and predators. 

•  Big population has more prey for the predators to feed on and more animals the parasites can attach to 
• A small population will not be as impacted by this type of limiting factor.

Density independent limiting factors - fire, flood, hurricanes, and pollution. natural disasters

• limit populations regardless of size

EXAMPLE: In a large or small ecosystem which has just experienced a hurricane, many of the organisms are going to die off, and the population size will decrease. If the hurricane kills 50% of the population, it is going to have the same impact in both ecosystems. Obviously with a larger...

Welcome to My AP Biology Thoughts podcast, my name is Victoria and I am your host for episode 27 called Unit 8 Ecology: Logistic VS Exponential Growth. 

Logistic Growth: populations grow as fast it can with the limited resource it has to support the growth, making the population growth dependent on the availability of resources, when resources start to decrease or come to a stop, that is called carrying capacity

• Exponential growth may happen for a while, if there are few individuals and many resources. But when the number of individuals gets large enough, resources start to get used up, slowing the growth rate. Eventually, the growth rate will plateau, or level off, making an S-shaped curve. The population size at which it levels off, which represents the maximum population size a particular environment can support, is called the carrying capacity, or K
• Any kind of resource important to a species’ survival can act as a limit, causing the carrying capa For plants, the water, sunlight, nutrients, and the space to grow are some key resources. For animals, important resources include food, water, shelter, and nesting space. Limited quantities of these resources results in competition between members of the same population, or intraspecific competition (intra- = within; -specific = species).

Exponential Growth: resources are unlimited, populations grow as fast as they can, J-shaped curve, the populations faces no predators, like an invasive species

Yeast (logistic growth) 

• a microscopic fungus used to make bread and alcoholic beverages, 
• can produce a classic S-shaped curve when grown in a test tube.
• In the graph shown below, yeast growth levels off as the population hits the limit of the available nutrients. 
• (If we followed the population for longer, it would likely crash, since the test tube is a closed system – meaning that fuel sources would eventually run out and wastes might reach toxic levels).

Spotted Lantern Fly (an Invasive species) or Bacteria 

• The Spotted Lanternfly is an invasive species that destroys fruit crops, trees and plants by hopping from plant to plant, crop to crop, and tree to tree. 
• Although native to regions in China,...

Welcome to My AP Biology Thoughts podcast, my name is CJ and I am your host for episode 26 called Unit 8 Ecology, The Population Growth Equation.  Today we will be discussing The Population Growth Equation.

• Let's start us off with a little bit of background knowledge. The population growth equation was founded in the late 18th century by a couple of biologists. The big one was Thomas Malthus. He saw that populations grew in a geometric pattern. He came up with two models. It is important that we distinguish these two models. One is for logistical growth and the other is for exponential growth. Just like in math, exponential growth is just a line on a graph that looks like a “J”. In fact, in biology, they are often called Exponential growth curves “J” curves. Now logistical growth is similar, up until a crucial point of the population. The curve seems to hit an impasse, or a number on the ‘Y'' axis that will never see a point. Instead of the line continuing up like in an exponential graph, it levels out and shoots to the right, as if hitting a limit. Now this limit is not just a number on an axis. This number represents the carrying capacity of an ecosystem. This carrying capacity is the maximum amount of species in a singular environment. This is most likely due to limiting factors, whether it be biotic or abiotic. Now limiting factors are things in an ecosystem that prevent a species from growing in population without a limit. Now biotic limiting factors are living things, such as lack of food or abundance of predation. These all can limit the total population of a species. Abiotic limiting factors are nonliving things, such as a storm or lack of water or pollution. All of which could kill off a population or make them compete for vital resources. 

• A huge example of exponential growth rates, are any invasive species. Invasive species in the dictionary are defined as having exponential growth in their population. No predators and unlimited resources. Where they go their population is destined to boom and show no signs of slowing. Invasive species we know and hold near and dear to our hearts are stink bugs, the Asian Giant Hornet, Asian Carps, Japanese Beetles, and of course, the Spotted Lantern Flies. All of these came over and had no predators, so naturally, they breed and reproduce unlimitedly. This is a huge problem because their large numbers knock out any other species with the same niche. 

• Enough about the qualitative information about Population Growth Curves, and to the quantitative. Exponential growth curves have an equation of dN/dT = rN. Now, dN/dT stands for the rate at which the population grows. R stands for the maximum growth rate per capita. N stands for the population size. There are other ways to find dN/dT however. The easiest is to subtract the total number of births in a year, with the total number of deaths. For the logistical curves, the equation

Welcome to My AP Biology Thoughts podcast, my name is Helena and I am your host for episode #25 called Unit 8 Ecology: endotherms and ectotherms.  Today we will be discussing the difference between endotherms and ectotherms. 

• Endotherms are organisms that use internally generated heat to maintain body temperature. They typically keep a steady body temperature regardless of their environment due a process called homeostasis. Homeostasis, which are mechanisms like shivering and sweating, keeps an endotherm's internal temperature steady. On the other hand, Ectotherms are organisms that mainly depend on external heat sources in order to regulate their body temperature. Their body temperature fluctuates based on their surrounding environment’s temperature. Their regulation methods include seeking sun when they need heat and shade when they need to cool down. Unlike endotherms, they are able to survive off of a range of body temperatures instead of needing to maintain a set temperature. Since ectotherms use outside sources for heat, they are able to eat much less food than endotherms. Ectotherms have a much lower metabolic rate than endotherms because they use a lot less internal energy to regulate their body temperature. About 50% of ectotherms food energy is used for growth and reproduction, while endotherms use most of their food energy during metabolism to maintain their body temperature. This is why endotherms require 5 to 20 times more food than an ectotherm of the same size. 

• Weather with a t-shirt on, just like every endotherm, you would start shivering. That is unless you are some kind of superhero. On the other hand, if heat generation exceeds heat loss, regulating mechanisms will increase heat loss. So if you were in Florida during August with a winter coat on you would start perspiring, or if you were a very hot dog you would start panting. Now onto Ectotherms, these are the organisms known as “cold-blooded animals”. Ectotherms include most fish, amphibians, reptiles, and invertebrates. When an ectotherm needs to increase its body temperature, it will seek out heat sources. For example, an alligator will bath in the sun, or a lizard will sit on hot pavement. On the other hand, when ectotherms need to cool off, they will seek out shade. For example, a lizard might go hang out under a shaded rock. However, some ectotherms regulate their body temperature by living in environments that have fairly constant conditions. These include a lot of marine invertebrates, who live in aquatic conditions that fluctuate very little, so they don’t have to seek out heat or cooling sources. Their body temperature matches that of the surrounding water. 

• So after learning all of this about ectotherms and endotherms, you might be wondering why organisms need to regulate their body temperature? Well the simple answer is that they would die if they didn’t. When cells are as cold as water’s freezing point crystals will form inside of them, which will most likely cause the cells membrane to rupture. On the other side, when the body gets too hot (above 104 degrees Fahrenheit)...

Welcome to My AP Biology Thoughts podcast, my name is Corrinna and I am your host for episode 24 called Unit 8 Ecology: Autotrophs, Heterotrophs, and Chemotrophs.  Today we will be discussing the differences between autotrophs, heterotrophs, and chemotrophs.

• Autotrophs, heterotrophs, and chemotrophs are organisms who obtain energy in different ways. Autotrophs create their own energy. The word autotroph comes from the root words auto which means self and trough which means food. Most autotrophs use the process of photosynthesis to make their food. This process creates sugars from carbon dioxide and sunlight. Autotrophs are also called producers because they provide oxygen and a food source for animals who are in higher trophic levels. Autotrophs form the base of ecosystems’ energy pyramid since they are eaten by herbivores.
• Herbivores are a type of heterotroph. Heterotrophs are organisms that consume other organisms in order to obtain energy because they cannot create their own food. There are multiple kinds of heterotrophs. Herbivores eat plants to obtain energy and are also called primary consumers because they eat the autotrophs, who are the lowest trophic level in a given ecosystem. Carnivores consume meat from other organisms. They are usually predators and can also be secondary and tertiary consumers. Secondary consumers eat herbivores and tertiary consumers eat other carnivores. Carnivores can also be scavengers, which are organisms that eat animals that are already dead.
• Chemotrophs can be either autotrophs or heterotrophs. They obtain their energy by the oxidation of electron donors in their environments. This means that they take electrons from available molecules and add oxygen to them to form other molecules for energy. Chemoautotrophs can synthesize their own organic molecules (include auto because they make their own energy). Chemoheterotrophs obtain energy by ingesting preformed carbon molecules since they can’t make their own.

• Some examples of autotrophs are most plants, phytoplankton, and some bacteria. All of these organisms create their own food. The majority of animals are heterotrophs. Deer, rabbits, and some bird species are examples of herbivores because their food source comes only from plants. Lions, snakes, and sharks are examples of carnivores because they get their energy from hunting and consuming other organisms. Bears, dogs, and humans are all omnivores because they eat both plant and animal matter. Scavengers include raccoons and turkey vultures, who usually eat other decaying animals. 
• Some examples of chemotrophs are some types of bacteria and fungi (but not all bacteria and not all fungi are chemotrophs). These organisms require carbon to survive and reproduce. Because they most often live in hostile environments such as deep sea vents, chemotrophs aren’t as well-known as autotrophs and heterotrophs.  

Welcome to My AP Biology Thoughts podcast, my name is Alex and I am your host for episode 23 called Trophic levels and  energy flow..  Today we will be discussing these ideas and their importance to ecology.

• Trophic levels are a means to categorize species in an ecosystem by their distance from the energy source. This separates species into different categories, such as producers, primary consumers, and secondary consumers, with some species being able to inhabit multiple categories depending on what they eat.
• Energy flow refers to how energy is transferred throughout an ecosystem. Energy generally flows in a linear direction, with energy going from low trophic levels to high trophic levels, with energy being lost to the environment as heat. So, what are examples of these ideas?

• A simple example of trophic levels would be an ecosystem of a plant, a worm, and a bird. In this ecosystem, the plant produces energy from the sun, the worm eats the leaves of the plant, and the bird eats the worm. This ecosystem would have the plant be the producer, as it gets its energy from the sun, with the worm being a primary consumer and the bird being a secondary consumer.
• Using this same ecosystem, we can also determine how energy flows through the system. The plant produces energy from the sun, and uses a portion of the energy to keep itself alive. This energy is lost to the environment as heat. When a worm eats the leaves, it gets only a portion of the energy that was made by the plant. The same thing happens to the bird: the worm uses some of the energy to live, and 

• These topics are extremely useful when explaining the number of organisms in each species. While producers are plentiful due to their ability to be self sufficient, we see that species which take up higher trophic levels exist in relatively small populations. This is due to the fact that only a fraction of energy is transferred between trophic levels, around only 10% per level. This makes food a huge limiting factor for many secondary and tertiary consumers, who have to constantly forage for relatively few calories. Although trophic levels and energy flow are relatively basic ideas, they are essential in understanding many interactions and population numbers of ecosystems.

Thank you for listening to this episode of My AP Biology Thoughts.   For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.  See you next time!

• "Ice Flow" Kevin MacLeod (incompetech.com)
• Licensed under Creative Commons: By Attribution 4.0 License
•  http://creativecommons.org/licenses/by/4.0/

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Welcome to My AP Biology Thoughts podcast, my name is Pauline and I am your host for episode 22 called Unit 8 Ecology: Food Web and Food Chains and types of organisms.. Today we will be discussing the classification of different organisms in each trophic level of food webs and varying food chains 

• To start off, let's differentiate between food chains and food webs. The picture shows how food chains are a smaller representation of an ecosystem, so several food chains within one ecosystem make up a food web. Therefore, a food chain will show only one organism at each trophic level, while a food web will show multiple producers for example. That brings us into identifying the types of organisms in these food chains and webs. At the bottom are the producers that convert the solar energy into chemical energy that can be used by other organisms. All producers are autotrophs, meaning they make their own food. These producers are eaten by herbivores known as primary consumers. The next trophic levels are made of secondary consumers, tertiary consumers and so on. These consumers are either omnivores or carnivores. Two other types of organisms that are often forgotten about are detritivores and decomposers. Detritivores consume material to break it down, so this would be like an earthworm. Decomposers feed off of dead decaying matter like fungi. Fungi release a liquid that breaks down the matter to suck up the nutrients. A key element of food chains is that only 10% of energy is transferred between trophic levels, so producers must provide a lot of energy to sustain the highest consumers. 

• A very local example of a food chain here in NJ is shown in the picture including grass as a producer eaten by a grasshopper, who would then be eaten by a small bird. This bird as a secondary consumer would be eaten by a snake as a tertiary consumer. And to take it one step further, an owl could eat the snake. This is an example of only one food chain, so a NJ food web would maybe also include a deer as a primary consumer and a fox as a secondary consumer. 

• Food webs and the role of each organism involved within the food chain fit into the greater picture of ecology because of the effects that changes in energy availability can have on the ecosystem. For example, if there is a decrease in the amount of free energy available to the producer...

Welcome to My AP Biology Thoughts podcast, my name is Shriya and I am your host for episode #21 called “Plant Behavior (phototropism, gravitropism, thigmotropism)”. Today we will be discussing the definitions of all of those concepts as well as a few examples to go along with them. Then, we will connect all of that to the overarching topic of evolution. Hope you enjoy!.

• We will be discussing the topic of plant behavior which is how plants respond to changes in their environments
• Like all organisms, they detect and respond to stimuli in their environments, but they cannot physically move to get away from danger since they are rooted to the soil
• Instead, a plants primary means of response is to change how it is growing based on a number of factors 
• Their responses are normally hormone based because they do not have nervous systems to control them
• They can have responses to both internal and external stimuli, however in this episode we will mainly be focusing on their external responses to stimuli
• Plant roots always grow downwards because they have specialized cells that respond to gravity which is an example of a tropism 
• A tropism is turning towards or away from a stimulus in the environment
• The first type of tropism is called phototropism which means the plant is growing towards a light source 
• This response is controlled by a plant growth hormone called auxin
• Auxin stimulates cells on the dark side of a plant to grow longer which provokes the plant to bend towards the light 
• The next type of tropism is called gravitropism, or geotropism where “geo” means the Earth and tropism refers to turning
• Gravitropism is the growth of a plant’s organ or change in the direction of its growth in response to gravity
• Since plant cells are able to sense gravity, if a root is not growing towards the center of the earth, the cells become aware of that and change it
• Auxin is also stimulated either at the root caps or the shoots to allow cell elongation
• Finally, there is also thigmotropism which is the response to touch 
• The stimulating factor is generally a hard surface that can change the direction of the plant’s growth or the growth of one of its organs
• Thigmotropism can be in the form of...

Welcome to My AP Biology Thoughts podcast, our names are Beth, Gillie, and Addie and we are your hosts for Unit 7: Examples of Evolution- The Threespine Stickleback. In episode 119, we will be discussing The Threespine Stickleback and how it relates to the AP Biology Curriculum. 

The Threespine stickleback fish live in the ocean and in lakes. The fish who live in the lake have been separated from the ocean sticklebacks for thousands of generations. Although there is a difference between ocean and lake sticklebacks, all freshwater sticklebacks can vary in shape and size depending on habitat. Scientists looked into the differences between lake and ocean sticklebacks by taking 50 fish from each population and comparing them.

Freshwater sticklebacks and ocean sticklebacks have a number of different physical characteristics. For example, Ocean Sticklebacks are generally much larger. They also differ in body length, spine length (and number), fin shapes, number of lateral plates (​​Genetic Science Learning Center, 2017, August). The scientists observed that the average number of lateral plates for ocean sticklebacks was 33. On the other hand, the average number of lateral plates was 5 in the lake stickleback. Additionally, Michael Bell ran an experiment where he determined just how fast this evolution was occurring. He tracked the genes of stickleback fish in lakes in Alaska and determined the speed at which evolution occurred (in just a decade) (Robert Sanders, M. R., & Sanders, R., 2021, June 21). More interesting, however, is the fact that fish evolved convergently across the globe due to similar conditions, despite being isolated for decades (Shen, H., 2012, April 04). 

The Threespine Stickleback demonstrates natural selection and adaptation in the environment, which directly relates to section 7.1 and 7.2. The data of how lake and ocean sticklebacks have adapted over time is a prime example of fitness. The environment of the lake and the ocean are different, and as a result, the lake stickleback has evolved to better suit this body of water. The evolution of the Threespine Sticklebacks caused by natural selection in different environments connects to 7.1 and 7.2.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

• "Ice Flow" Kevin MacLeod (incompetech.com)
• Licensed under Creative Commons: By Attribution 4.0 License
• http://creativecommons.org/licenses/by/4.0/

• Apple Podcasts

Welcome to My AP Biology Thoughts podcast, my name is Nidhi and I am your host for episode 20 called Unit 8 Ecology: Animal Behaviors Part 2: Instincts, Fixed-Action Patterns, Imprinting, and Associative Learning.  Today we will be discussing some of the different animal behaviors, what causes these behaviors, and how this connects to ecology.

• Animal behavior includes all the ways animals interact with other members of their species, with organisms of other species, and with their environment. These behaviors are prompted by both internal and external stimuli. Animal behaviours can be both innate and learned. Innate behaviors are genetically hardwired and learned behaviours are learnt through the individual animals experience. All animals are said to have innate behavior apart from humans. Humans have instincts, like the instinct to eat, but this can be influenced by human consciousness and the environment. An instinct is the ability of an animal to perform a behavior the first time it is exposed to the proper stimulus. This is an animal's first reaction and since it doesn't have to be learned, it is an innate behavior.

• naturalist, found that when young birds came out of their eggs they would become attached to the first moving object they encountered. In most cases in the wild, that would be their mother. But Lorenz replaced himself as the object of their affection. They would also attach to inanimate objects like a white ball and an electric train – if it was presented at the right time. Associative learning is where animals learn something based on a stimulus. A new response becomes associated with a particular stimulus and this applies to almost all learning done by animals with the exception of habituation. This type of behavior is learned over time. An example of this is Pavlov’s dogs. Pavlov started his experiment from the idea that dogs don’t learn to salivate whenever they see food. This reflex is an instinct .In his experiment, Pavlov used a metronome as his neutral stimulus. By itself the metronome did not elicit a response from the dog's. Next, Pavlov began clicking the metronome before he gave food to his dogs. After a number of trials of this, he presented the metronome on its own. The sound of the clicking metronome on its own now caused an increase in salivation. So the dog had learned an association between the metronome and the food. 

• These behaviors can be connected to the greater topic of ecology. Ecology looks at the responses of organisms to their environments and animal behaviors are animals behaviors to stimuli often caused by their environment. These behaviors can also be connected to the idea of taxis behaviors since many of the behaviors follow a pattern and can be predicted. Certain behaviors can also help an organism survive to reproduce, making them more fit. An example of this is the instinctive behavior of baby birds to open their mouth for food. The birds that are genetically hardwired with the behavior to open their...

Welcome to My AP Biology Thoughts podcast, my name is Adrienne and I am your host for episode #19 called Unit 8 Ecology: Animal Behavior Part 1. Today we will be discussing learned behaviors including associative learning, trial and error, habituation, observational learning, and insight and how it ties into the greater picture of ecology.

General introduction

• Animal Behaviors: how animals interact with each other and their environment
• Learned behaviors: behaviors developed through experience or are taught

Definition of Animal Learned Behaviors

• Associative learning: learning to correlate a stimulus with a consequence or effect
• Trial and error/operant conditioning: learning to associate a behavior with a reward or punishments
• BF Skinner theory: belief that learning and changes in behavior are caused by an individual’s response to stimuli. The response either leads to a consequence or reward and over time, it reinforces/alters how an organism responds.
• Habituation: decrease in response to a repeated stimulus that causes little effects/impact, enables animals to disregard unimportant stimuli 
• Insight: uses reason and past experiences to solve problems and form conclusions

• Associative: Pavlov’s dogs, giving dogs steak and ringing the bell leads the dog to start salivating over time when the bell is rung because it associates it with steak
• Trial and error/operant conditioning: in the Skinner box, a mouse learns to press the level because the pressing level behavior leads to a reward (food pellet)
• Habituation: over time baby birds will stop fearing leaves falling since they learn that it poses no harm
• Observational learning: baby wolves wolves observe and copy the behavior of adult wolves when they hunt which teaches them predatory skills and effective hunting behaviors such as hunting in packs and surrounding its prey
• Insight: Jane Goodall observed that chimpanzees use twigs as a tool to “fish” for food
• They would use the twig and poke a hole into a termite mound and eat the insects clinging to it. 
• Over time, they have been seen making several different types of tools such as sharpening sticks for hunting and stones as hammers to crack open nuts.

How does this topic fit into the greater picture of...

Welcome to My AP Biology Thoughts podcast, my name is Jacky and I am your host for episode 18 called Unit 8 Ecology: Innate, Learned, and Complex Behaviors.  Today we will be discussing the different behaviors animals engage in in response to stimuli.

• Animal behavior is how animals interact with one another and to the environment. The behaviors are specifically triggered by stimuli, which can be internal or external. 
• EX internal: Need to maintain homeostasis. If an animal eats some bad food, they’re body will often react in a manner to try to throw up that food
• EX external: Changes in weather will often lead to migration, where an animal leaves their habitat to go to a whole new region
• Three main types of behaviors: Innate, Learned, and Complex
• Innate and Learned are two distinctive categories of behaviors, Complex is a mixture of both

• Innate behaviors are behaviors animals are genetically programmed to engage in. They are instinctive, and are automatically performed by an animal in response to a stimulus.
• Three types: Reflexes, taxis and kinesis. For these 3, I will be using an example of shining light.
• Reflexes: A natural response to a stimulus. It was with you the day you were born; an automated reaction by your body. When you go to the doctor, they shine light in your eye. Automatic reaction, or reflex, is to blink or squint; you don’t even think about it.
• Taxis: Movement away from or toward a stimulus. It is not random; it is a purposeful response of the animal. If you shine a light in the air at night, you will notice bugs gravitate towards it. This is a natural behavior of theirs; they are attracted to sources of light and will move to it, especially during night time.
• Kinesis: Random movement. There is no defined purpose in the behavior, it is simply stray movement that occurs when a stimulus is introduced. The animal is not moving toward or away from anything. If you are in a dark cave and then shine a light on a cluster of rats, they will scatter and move around erratically, not going anywhere in particular. They are not trying to move toward or away from the light, they are just trying to move.
• Learned behavior: Behavior that is acquired through experience. It is not a reaction one will have from birth. Some common examples of learned behavior are habituation, classical conditioning, and operant conditioning, observational learning, and insight learning. Will be using example of fire alarm
• Habituation: When the natural response to a stimulus decreases overtime as the animal is repeatedly subjected to the stimulus, causing them to become almost...

Welcome to My AP Biology Thoughts podcast, my name is Arthur and I am your host for episode 17 called Internal and External Stimuli. Today we will be discussing the different kinds of stresses induced upon organisms that evoke different responses.

Important Definitions:

• Internal stimulus:
• A stress that comes from within the organism to provoke a response.
• External stimulus:
• A stress from the outside environment induced upon an organism.  
• Homeostasis:
• The state of stability where all essential biological functions can optimally be carried out.  

Internal Stimuli:

• Hunger:
• Obtain glucose to carry out cellular respiration.
• Thirst
• Obtain water to allow for breathing and the transportation of oxygen throughout the body.  

External Stimuli: 

• Temperature:
• Endotherms need to maintain their core body temperature so if the outside environment is too hot or too cold, the organism will respond in a way to maintain the core temperature.
• Ectotherms need certain temperatures in order to maintain their metabolism, so they will either move to warmer or colder locations.  
• Sunlight:
• Plants when hit with sunlight will experience phototropism in order to allow them to get the maximum amount possible. 

The existence of food webs and chains is dependent on organisms consuming one another. In order for this to happen, the consumers need the stimulus of hunger.  

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

• "Ice Flow" Kevin MacLeod (incompetech.com)
• Licensed under Creative Commons: By Attribution 4.0 License
•  http://creativecommons.org/licenses/by/4.0/

• Apple

Welcome to My AP Biology Thoughts podcast, my name is Corrinna and I am your host for episode 14 called Unit 7 Evolution: Convergent and Divergent Evolution.  Today we will be discussing the differences between convergent and divergent evolution.

• Convergent and divergent evolution are different types of evolution, and there are many examples of each.
• Convergent evolution is when two unrelated species evolve to have analogous structures due to similar natural pressures in their respective environments. Analogous structures are structures that have similar functions in unrelated organisms. Because convergent evolution takes place due to similar pressures in different environments, it makes sense that it produces analogous structures since these structures have similar functions.
• Speciation is when distinct species evolve during the course of evolution. Divergent evolution is a type of speciation. Divergent evolution is when different species evolve from a common ancestor, which is a result of the original group developing differences in reaction to different pressures in their environments. Divergent evolution produces homologous structures, which are structures in different organisms that serve different purposes but have similar structures, which suggest a common ancestor. 

• There are many examples of both convergent and divergent evolution. One example of convergent evolution is the evolution of wings in both birds and bats. Although birds and bats did not originate from the same common ancestor, the structure of both wings are supported by a modified five-fingered limb. Birds and bats show convergent evolution because their similar structures were developed as a result of similar environmental pressures rather than a common ancestor. Another example of convergent evolution are placental mammals and marsupials. Placental mammals, which live in Europe, Africa, and America, undergo gestation in their mother’s uterus and are born fairly advanced, while marsupials are born immature but develop in their mother’s pouches. Marsupials live in Australia. Because each group developed similar analogous structures because of similar habitats and feeding patterns, placental mammals and marsupials show convergent evolution. It is clear that these groups didn’t have a common ancestor because they give birth in different ways, but environmental pressures allowed them to develop similar structures. 
• One example of divergent evolution is the different kind of finches that Darwin discovered on the Galapagos islands. Finches on different islands had developed different beak structures due to different food sources. For example, Finches that ate insects had longer and thinner beaks than finches who ate seeds, who had short and thick beaks. These finches all evolved from the same common ancestor, but developed specific beak structures due to different environmental pressures. The finches eventually evolved enough that they became different species. Another example of divergent evolution is the evolution of primates. All primates evolved from a single ancestor which lived around 65 million years ago, when the continents were mostly connected. As the continents split and primates moved to different environments, they evolved to develop traits that would be beneficial in those environments. 

• Convergent and divergent evolution both prove evolution and natural selection. Convergent evolution shows that similar environments can produce similar...

Welcome to My AP Biology Thoughts podcast, my name is Adrienne and I am your host for episode 9 called Unit 7 Evolution: Allopatric vs. Sympatric Speciation. Today we will be discussing the differences between allopatric and sympatric speciation and I will provide examples for each.

• Speciation: formation of a new species, occurs when a group of organisms isn’t capable of interbreeding and producing viable offspring anymore
• Allopatric speciation: occurs through geographical isolation like a physical geographic barrier
• Sympatric speciation: occurs without a geographical barrier
• Driven by other factors: habitat differentiation and sexual selection. 

Allopatric speciation

• Ex. Isthmus of Panama: narrow strip of land that causes a geographical barrier between Caribbean sea and Pacific ocean
• Two species of porkfish have emerged 

• Prezygotic barriers: before the sperm and egg
• Habitat: different times of year organisms reproduce
• Ex. 2 related frog species, Rona aurora breeds earlier in the year than Roma poyilil making them unavailable for each other 
• Behavioral: set of certain behaviors that must be executed to reproduce
• Ex. New Birds of Paradise and Birds of Paradise have different courtship characteristics
• Mechanical: the sexual parts must fit like a “lock” and “key”
• Ex. 20 different species of Bush Babies, different sexual parts won’t fit and allow reproduction
• Gametic isolation: if the gametes are incompatible, the organisms won’t reproduce
• Ex. Cells of red and purple sea urchins are genetically incompatible, fertilization is impossible
• Postzygotic barrier: after sperm and egg
• Inviability: organism dies before reproduction
• Infertility: organisms can’t form gametes
• Breakdown: F2 generation doesn’t sexually develop properly
• Ex. Horses and donkeys

Welcome to My AP Biology Thoughts podcast, my name is Arthur and I am your host for episode 16 called Fossil Record Radioactive Dating. Today we will be discussing the techniques used to precisely determine the age of fossils. 

• A powerful tool that scientists can use to precisely determine the age of samples is radioactive dating. 
• Exponential decay: The amount of a substance decreases in proportion to its current value.  
• Half life: A constant amount of time for the amount of the remaining sample to halve.  
• Carbon 14: A naturally-occurring radioactive isotope of carbon present in small quantities in all organisms. It has a half life of around 5700 years. 

• Since all living organisms are constantly exchanging carbon with the environment, an organism will have around 1 C-14 atom per 1 trillion carbon atoms. Once an organism dies, it stops exchanging carbon with the environment, so the amount of C-14 remaining in the organism will exponentially decay. By observing the amount of C-14 remaining and comparing it to the established baseline amount, we can calculate the age of samples. For example, if we had a tissue sample with an observed C-14 concentration of one per 4 trillion carbon atoms, as that is a quarter of the original amount, we know that two half lives have elapsed, meaning the sample is around 11400 years old. We were able to determine that the preserved “Ice Man” is around 5300 years old via this method. The amount of carbon-14 had to have been 1 atom per 1.9 trillion carbon atoms.

Sources: https://www2.lbl.gov/abc/wallchart/chapters/13/4.html

• How does this topic fit into the greater picture of evolution?
• By being able to accurately date ancient samples, we can create temporally accurate phylogenetic trees, allowing us to better understand organisms’ ancestry and evolutionary relationships.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts, make sure that you visit www.hvspn.com. Thanks for listening!

• "Ice Flow" Kevin MacLeod (incompetech.com)
• Licensed under Creative Commons: By Attribution 4.0 License

Welcome to My AP Biology Thoughts podcast, my name is Alex Jing and I am your host for episode 15 called Homologous Vestigial and Analogous Structures.  Today we will be discussing what these different structures are and how they relate to evolutionary biology.

• So, what are homologous, vestigial, and analogous structures? Each of these terms refers to the structure of something about an organism in a different way. 
• Homologous structures are organs or skeletal elements that, due to similarity, suggest that they come from a common ancestor. These structures do not necessarily look the same, but are instead just structurally similar.
• Analogous structures are similar structures that evolved to serve the same purpose. These structures were not from some common ancestor, but instead were developed in multiple species independently to adapt to a similar environment. 
• Vestigial structures are remnants of some past feature of the organism that is no longer useful. It usually occurs when a species inhabits a new environment, or is in a new niche, that does not require an old structure.

• An example of a Homologous structure are the wings of birds. The wings of birds come from some evolutionary ancestor, but have become diverse due to different birds needing different wings for their environment. Many predatory birds have wings that are specifically good at catching air so they can accelerate fast enough to catch prey. On the other hand, smaller birds that get sustenance off of fruit have wings that work better when flapping, and are used to maintain stability while eating in the air.
• An example of an analogous structure are the wings of a penguin and the flippers of a seal. Antarctica is a cold, barren environment, filled with sheets of ice and freezing water. Both the wings of a penguin, and the flippers of a seal were adapted to inhabit this environment. Despite the structure not coming from a recent ancestor, both animals use these limbs to be able to both traverse slippery ice, and swim in freezing water. 
• An example of a vestigial structure is the leg bone of a whale, where despite being a waterbound creature, it has remnants of a limb that was used for movement on land. This is because whales came from an ancestor that is shared with pigs. This ancestor was a land animal, but since whales only swim, they did not need this leg anymore. Due to lack of use, this limb became a smaller and smaller part of the whale, and eventually came to be this small separated bone in the whale's skeleton.

• Now why are these things important? Well, these structures are extremely useful for understanding the evolutionary history of animals. Homologous structures are useful for...

Welcome to My AP Biology Thoughts podcast, my name is Chloe and I am your host for episode 13 called Unit 7 Evolution: Adaptive Radiation in Darwin's Finches. Today we will be discussing the diversification of the mainland species of finches due to adaptive radiation. 

• It’s important to understand what this all means. Adaptive radiation is a process in which organisms diversify rapidly from an ancestral species into a variety of new forms. A change in environment can introduce a species to new available resources, and can open new environmental niches. These openings cause new competition within the species, eventually leading to a certain trait being more advantageous. 
• This ties in perfectly with the natural selection mechanism which describes the relationship between overpopulation, variation, competition, fitness, reproduction . The widespread of niches on the Galapagos makes a perfect fit for this mechanism to take place, and for rapid speciation to occur. 
• This brings us right to the important stuff, the finches. The theory is that a  small population of mainland finches migrated to each of these islands with different niches, creating competition for a certain type of resource. 
• Variation caused one particular trait to be  more beneficial than others, causing rapid speciating among these populations 

• The finches varied in beak sizes and fur color. 
• Larger beaks were beneficial in niches where the available food source mostly consisted of  large, difficult to open nuts while Smaller and thinner beaks were beneficial where the main source of food was insects because their small beak  made it easier to prey on small bugs. This made it easy for competition to take its route, and let the finch that is more fit for the specific food source to survive and reproduce. 

• To dig in deeper, it’s important to realize how this information is still relevant. This observation that Darwin made gave him evidence for his theory of natural selection that we still use today. The natural selection mechanism that we study still continues to cause organisms to evolve and speciate. Another important concept to this specific example of adaptive radiation is the divergent evolution that occurred, and how each population became a new species due to the available resources. Biogeography also helped Darwin understand the relatedness of the finches on different islands because their closeness in geography helped prove that they were related in some way

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts, make sure that you visit www.hvspn.com. Thanks for listening!

Welcome to My AP Biology Thoughts podcast, my name is Helena and I am your host for episode 12 called Unit 7 Evolution on Miller and Urey..  Today we will be discussing the first experiment to prove that organic molecules can be formed from inorganic compounds.

Stanley Miller and Harold Urey were biochemists at the University of Chicago in 1952, who wanted to explore how life came to be billions of years ago. They created an experiment that was meant to simulate the conditions that they believed could have existed on young earth billions of years ago, around the time the first life was thought to have formed. The point of their experiment was to test what kind of environment needed in order to create life. Their experiment tested Primordial Soup Theory developed by both Alexander Oparin and J.B.S. Haldane. The theory states that energy (lighting and rain) energized the gases in earth's early atmosphere to create simple organic compounds that formed an organic “soup”. This soup eventually turned into complex organic polymers and lastly life. 

Miller and Urey tested this theory by designing an experiment in which they used a glass flask attached with a pair of electrodes, to hold water, methane, ammonia, and hydrogen, which were the main components of young earth's atmosphere. This flask was connected to another flask that was half filled with water, and held over a heating source. When the water was heating it vaporized and mixed with the gas mixture. As this was happening electrical sparks were fired between the electrodes to simulate lighting. This simulated atmosphere was cooled so the water condensed in order for it to sink into a U-shaped trap at the bottom of the apparatus. After a day the solution in the trap turned pink, and at the end of the week they removed the boiling flask and added mercuric chloride to prevent microbial contamination. They stopped the reaction by adding barium hydroxide and sulfuric acid. They then evaporated it to remove impurities. They found that 10%-15% of carbon present was in the form of organic compounds. Miller and Urey used paper chromatography and found that 2% of the carbon went into amino acids, including 13 of 22 amino acids essential to make proteins in living cells, glycine being the most abundant. 

While the experiment only created organic molecules and not a living biochemical system (which in reality would take thousands of years), the results were still, to a large extent, enough to prove the primordial soup hypothesis. This is significant because the experiment was the first to show that organic molecules can be formed from inorganic compounds. It also inspired various other experiments, building more evidence for this theory of the origin of life.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts, make sure that you visit www.hvspn.com. Thanks for listening!

Welcome to My AP Biology Thoughts podcast, my name is Raelynn and my name is Samiyah and we are your hosts for Unit 7: Examples of Evolution - Plants and Birds. In episode 118, we will be discussing the plant Babiana ringens and how it has evolved to attract sunbirds.

• The Babiana ringens plant in South Africa evolved in such a way that increases the chance of  Nectarine famosa, or the malachite sunbird - their main pollinators- to stop by and drink nectar out of their flowers. In the certain region that these plants reside, most sunbirds avoid predators by staying away from the ground- as such, the Babiana ringens evolved to create a small perch, making it easier for birds to drink their nectar, and thus pollinate them, which in turn increased their evolutionary fitness. 

• Through a study conducted by botanist Spencer Barrett from the University of Toronto Canada, along with a team of researchers, they found that the sunbirds in the specific region of South Africa in which the plants with the perches reside used the perches to pollinate the plants, and were their main pollinators. 
• They went on to study other Babiana ringens plants across South Africa and found that they didn’t have the perches, and after studying them for some time, realized that their main pollinators weren’t the sunbirds that require the perches to make pollination easier. As such, the perch was an adaptation to the environmental pressures (of their main pollinators having been sunbirds). 

• The interactions between Babiana ringens and sunbirds demonstrate the concept of evolution and natural selection. The flowers with the perch were more “fit” for the environment since it encouraged the birds to perch on them and pollinate the flower. As a result, the Babiana ringens with the genes for the perch were able to both outlive and outpopulate those without perches. Over time, the gene for flowers without this stem faded away from the gene pool, and it became characteristic of Babiana ringens

Welcome to My AP Biology Thoughts podcast, my name is Pauline and I am your host for episode #11 called Unit 7 Evolution: Genetic Drift Founders and Bottleneck. Today we will be discussing one of the four evolutionary forces called genetic drift and its two examples.

• There are 4 evolutionary forces that drive changes in a population’s genetics; these include natural selection, sexual selection, genetic drift, and gene flow
• The Founders and bottleneck effect fall under the evolutionary force of genetic drift
• Genetic drift consists of random non-adaptive changes due to a random event
• The Founders effect takes place when members of a population migrate to a new area. The founder's effect is usually a catalyst to adaptive radiation which is an evolutionarily rapid change between populations
• The bottleneck effect occurs when a population experiences a catastrophic event (due to natural disaster, overharvesting, or habitat loss) that results in the survival of only a small number of individuals, who represent only a fraction of the genetic diversity that was present in the original population. 

• Founders effect: This is exemplified by the Eastern Pennsylvania Amish population. Their ancestors migrated from Germany to found their community. The Amish typically marry from within their own community and are isolated, so genetic mutations tend to persist. For this reason, the Ellis-van Creveld syndrome is much more prevalent among their population. The main symptoms of this disorder is short stature and abnormal numbers of fingers and toes. 
• Bottleneck effect: A common example of this involves the Northern elephant seals. Humans inflicted upon them a population bottleneck through seal hunting. Hunters harvested the Northern elephant seal for its blubber to make oil. The blubber of one adult male elephant seal could produce up to 25 gallons of oil. By the late 1880’s, the seals were considered functionally extinct due to excessive harvesting. The effective breeding population reached a low point of 20-100 individuals. These survivors were moved to Guadalupe island to recover.

https://www.thoughtco.com/what-is-the-founder-effect-4586652

https://www.fisheries.noaa.gov/species/northern-elephant-seal

Welcome to My AP Biology Thoughts podcast, my name is Morgan and I am your host for episode # 10 called Unit 7 Evolution: Types of Selection. Today we will be discussing Directional Selection, Disruptive Selection, and Stabilizing Selection.

• All three are subsets of natural selection (response to environmental changes)
• All three cause a change in genetic variance of a population- alleles in the gene pool
• Directional selection- SHIFT in gene pool, favors one phenotype
• Disruptive selection- INCREASE in variance, selects extreme phenotypes and disregards ‘middle ground’
• Stabilizing selection- opposite, DECREASES variation in gene pool, gets rid of extremes and takes average

• Directional selection is shown through peppered moths (graph of curve moves to the right on spectrum light to dark) single phenotype favored. Result of a drastic environmental change
• Disruptive selection- mice on light sand, mice in dark grass, no middle ground (graph moves from one curve to two curves, little to no middle population) drives speciation since two populations separate
• Stabilizing selection- population of mice, this time on forest floor which is medium brown, both light and dark will stand out and not be as fit (graph goes from wide curve to narrower with more in the middle and less at sides)
• Examples shown on graphs used from the website Bio.LibreTexts.Org

• Overall, all three contribute to changes in populations and shifting of traits. Leads to speciation, especially disruptive. Under the umbrella of natural selection. 
• Def. of evolution- process of organisms changing, developing and diversifying over time.
• Relates to central dogma since mutations in the gene sequences are what causes any changes in phenotypes. Difference in the DNA leads to a difference in the code sent to the RNA and therefore a difference in the protein it makes

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts, make sure that you visit www.hvspn.com. Thanks for listening!

• "Ice Flow" Kevin MacLeod (incompetech.com)
• Licensed under Creative Commons: By Attribution 4.0 License
• http://creativecommons.org/licenses/by/4.0/

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My AP Biology Thoughts

Welcome to My AP Biology Thoughts podcast, my name is Charles but you can call me Darwin and I am your host for today. This is podcast number 8 called Evolutionary Relationships. Today we will be discussing Phylogenetic trees and Cladograms.

Phylogenetic Tree- 

• A diagram that shows evolutionary relationships among species 
• Uses DNA sequences to find patterns in species
• There is a distinct difference between cladograms and phylogenetic trees. Cladograms are shaped like a “y” but with a lot more lines branching off. This diagram is based on hypothesis and does not use DNA sequencing. It’s mainly based on homologous structures and noted similarities between animales. Each protruding line from the base represents a time where a structure split off, such as a heart having 4 chambers or having webbed feet.  
• Phylogenetic trees are mainly used to show time. It is shaped like a very geometric tree sideways. The trunk is the common ancestor for all of the species at the tip of the branches. Each junction represents a closer common ancestor. If a line stops short, that usually means the species went extinct.

Cladograms-

• DNA sequencing is a process of finding common ancestors. Since All cells have DNA, which contain a series of different letters that describe that organism. If some of the sequences in DNA matches that of another species, that could mean they are related or share a common ancestor. 
• are different ways to find the common ancestor of a species, one way is to find homologous bones structures in creatures, which could relate species. However, the most definitive way to find common ancestors, is to look at similarities in DNA sequences. 

• There are tons of examples, and you can search up a diagram for any animal. Looking at a human Phylogenetic tree, we can see that humans are more closely related to chimpanzees than any other monkey. Also, Humans are more closely related to cats, than cows. In addition to looking at phylogenetic trees, you could look at similarities in DNA sequences. Cats are 85% similar to humans, while cows are about 80% similar. It doesn’t seem like cats should be my brothers, however that remaining 15% has critical DNA letters that change various aspects of a creature. If we were to look at a cladogram, we would see the line for humans would be separate from cats, and the segment in between would represent a time where fur stops being useful or hind legs are being primarily used. 

How does this topic fit into the greater picture of evolution?

Cladograms and Phylogenetic trees come hand in hand when determining common ancestors. These common ancestors are the key to seeing how the species was able to evolve and split off into different organisms. While cladograms help us determine specific structures and when organisms split off, they are not scientific....

My AP Biology Thoughts

Episode 7

Welcome to My AP Biology Thoughts podcast, my name is Victoria and I am your host for episode #7 called Unit 7 Evolution: Evidence of Evolution. Today we will be defining the 4 Pieces of Evidence for Evolution, giving examples of each, and making connections to the unit of evolution. 

What is evolution?

• A change in the allelic frequencies of a gene pool 
• Continuous 

4 Pieces of Evidence of Evolution - 

1. Fossil Record
2. the preserved remains of traces of any organisms from the remote past, included both discovered and undiscovered
3. Only the hard parts of an organism are preserved 
4. Fossil evidence can be either
5.  Direct (body fossils): bones, teeth shells, leaves
6. Indirect (trace fossils): footprints, tooth marks, tracks, burrows
7. Like timeline, different kinds of organisms do not occur randomly but are found in rocks in a consistent order, this is known as the law of fossil succession 
8. It is incomplete, and requires an unusual combination of specific circumstances for it to occur, creating many gaps in the fossil record 
9. Biogeography:
10. Organisms located in one area of the planet are closely related than those found in other parts of the planet
11. It describes the distribution of organisms, over geographical areas, both in the past and present
12. Comparative Anatomy:
13. The comparison of the anatomic features of different species
14. 2 Key types of structures that support this
15. Homologous structures
16. Demonstrate a similar underlying anatomy due to shared evolutionary origin, but have evolved into a variety of distinct forms or speciation due to the presence of different selective pressures
17. The more similar the homologous structures between the two species are, the more closely related they are likely to be
18. Adaptive radiation through divergent evolution, as similar basic organisms have been adapted to suit various environmental niches 
19. Analogous structures 

Welcome to My AP Biology Thoughts podcast, my name is Nikki and I am your host for episode #6 called Unit #7 Evolution: Hardy Weinberg Equilibrium.. Today we will be discussing the conditions for a Hardy Weinberg equilibrium, the importance of it, and the equation used to find the characteristics of it

• Hardy Weinberg is the use of equations to find out allele and genotype frequencies in a population if Evolution didn’t occur. 
• This allows us to see what the population should look like without evolution
• Dominant vs recessive(p or q)
• P and q
• q^2 and q^2
• p+q+1
• p^2+q^2+2pq=1

So when do we use these equations? Well to use Hardy Weinberg, there can’t be any evolution taking place

Let's remember the 5 fingers of evolution

• Genetic drift- little genetic variation, random non-adaptive changes due to random event
• Bottleneck or founders
• No random events and no migration to new areas
• Bison being hunted and now little genetic variation
• Non-random mating/ sexual selection
• Peacocks with larger and brighter feathers
• Mutations
• Mutation changing fur color to a totally different color
• Gene flow-bring alleles together
• Purple bird
• Natural selection-non-random adaptive changes
• finches

Uncoincidentally the 5 requirements for Hardy Weinberg is

• No genetic drift
• No sexual selection
• No mutations
• No gene flow
• No natural selection

How does this topic fit into the greater picture of evolution?

This topic helps us see a population without evolution

Then, comparing to the actual population with evolution, and there are differences between the hardy weinberg and actual, that shows evidence of evolution as well as how evolution effects 

Welcome to My AP Biology Thoughts podcast, my name is Shriya and I am your host for episode 5 called “Population Genetics: Central Dogma, Allele Frequency Equation and Gene Pools.” Today we will be discussing the definitions of all of those concepts as well as a few examples to go along with them. Then, we will connect all of that to the overarching topic of evolution. Hope you enjoy!

Introduce the episode topic

Include definitions and vocabulary

• Will be discussing the topic of population genetics which is the study of genetic variation within a population and looking into changes in the frequencies of genes and alleles in populations over time
• Natural selection is one of the most influential factors that can affect a population’s genetic composition
• Central dogma of biology is when the instructions contained in DNA are converted into a functional product, a phenotype
• DNA, contains the genes that determine who you are, and proteins determine the structure and function of all your cells
• It describes the two-step process, transcription and translation, of how information in genes flow into proteins, creating a string of amino acids called polypeptides
• The DNA has the information which is used by the RNA to make the proteins
• The Allele Frequency Equation: an allele is a version of a gene and a heritable unit that controls a particular feature of an organism
• The allele frequency refers to how often a particular allele appears in a population
• An equation called the Hardy-Weinberg equation is used to calculate the genetic variation in a population: p^2 + 2pq + q^2
• p^2 and q^2 are the allele frequencies of the homozygous recessive and homozygous dominant, and 2pq is the allele frequency of the heterozygous genotypes
• To get p and q individually, you calculate actual/total # of alleles
• With this knowledge, you are able to calculate the total allele frequencies using the equation p + q = 1
• The gene pool is calculated using the equation just mentioned, p + q = 1 since it is the sum of both allele frequencies
• A gene pool is the collection of different genes within an interbreeding population, and refers to its genetic diversity
• The larger the gene pool, the greater genetic diversity, and the better a population is able to withstand environmental challenges

Have a natural transition into an example… no need to say “segment 2”

My AP Biology Thoughts

Episode #4

Welcome to My AP Biology Thoughts podcast, my name is Sid and I am your host for episode #4 called Unit 7 Evolution: Artificial Selection. Today we will be discussing what artificial selection is, examples of it and how it connects to evolution.

• Artificial selection is when humans use genetic variation in a population of species in order to select which traits they want passed down. Artificial selection occurs when human intervention in a species causes significant change in a gene pool.

• Dogs are one of the best examples of artificial selection. Today, when you’re walking down your street you may notice many different kinds of dogs. Some are large, some are small, some have brown fur, some have black fur. But why do all of these dogs look and behave so differently? This is because of artificial selection. Despite their many differences, all dogs are the same species. And as I said before, different dogs will look different, act different and have different sets of advantages and disadvantages. Humans have been using this for thousands of years in order to get these loyal companions for many different purposes. Thousands of years ago, dogs’ ancestors were just wolves. After humans tamed and bred them for thousands of years, they have become what we see today. However, humans didn’t just breed them randomly. They were selective in what traits they considered advantageous and made sure those were the traits that were to be passed down. For example, rottweilers were bred specifically to herd cattle. In order to breed a dog to do such a task, humans purposely breed two dogs with characteristics that would allow them to be efficient herding dogs. By doing this, humans select which traits they want passed down to the next generation of dogs for their own advantage. More examples of this are terriers that are good for catching rodents. In the early stages of what we see as dogs today, the wolves that have become dogs were probably those that were genetically capable of being more comfortable around humans. These wolves likely were able to eat remaining food that humans had left over allowing them to survive and reproduce which caused more wolves that were comfortable around humans. So initially, this was natural selection. After a while humans may have found use for these wolves. Some were able to get rid of pests, some were able to herd, some offered protection. They allowed those wolves to reproduce and after many years we now have dogs as we see them. Today, since a wolf and a dog would be unable to mate, we know that they are now different species entirely. 
• Examples of artificial selection in different species occur as well. On farms, chickens, cattle, sheep, and pigs are the result of artificial selection and selective breeding. For cows, farmers would selectively breed cows to have cows that serve their purpose the best. They may choose cows that are best suited for meat to reproduce and create more cows that can be turned into meat for human consumption. Farmers also might breed cows that are best suited for milk production together to create more generations of cows that are best for milk production. This is done for a variety of farm animals for a variety of purposes. Still, farmers don’t use artificial selection on just animals. Artificial selection is used to create cabbage, broccoli, cauliflower, brussel sprouts,...

My AP Biology Thoughts

Episode #3

Welcome to My AP Biology Thoughts podcast, my name is Nidhi and I am your host for episode 3 called Unit 7 Evolution: Darwin’s Early Influences. Today we will be discussing what led Darwin to researching and creating his theory of evolution.

• Our current belief of evolution is that species change in characteristics over several generations and this can be caused by natural selection. These characteristics are the expressions of genes that are passed on from parent to offspring during reproduction. Natural selection is the process where organisms better adapted to their environment tend to survive and produce more offspring. As a result, the traits that help the organisms survive will be passed down and the gene pool will shift causing evolution. 
• Darwin’s theory of evolution stemmed from the idea of natural selection. Darwin’s early life can be broken up into 2 parts. The first was his education and influence of his father and the 2nd was his voyage aboard the HMS Beagle. 

• One of Darwin’s early influences was his father. His father, Robert Waring Darwin’, had made Medical observations that Darwin would read to learn about human psychology. He was sent by his father to study medicine at Edinburgh University when he was 16. He described this experience as formative. And He believed he received the best science education he could have at a British university. Edinberg was where he was first exposed to the belief that animals share all of humans mental capabilities. This is an early belief that evolved into his research of evolution and the connection between species. He began to research this and was accompanied by his mentor Robert Edmond Grant when he learned about sponges in an effort to unlock the mysteries surrounding the origin of more complex creatures. 
• Darwin formulated his theory of evolution in private from 1837-1839 after returning from a voyage around the word aboard the HMS Beagle. On his journey aboard, he spent 5 years along the coast of South America exploring the continent and the Galapagos Islands. He filled many notebooks with observations on animals, plants, and geology and collected many specimens he sent home to study. Later in his life, he called the Beagle voyage the most important event in his life, saying it determined his whole career. Before the voyage he was planning a career as a clergyman but when he returned he was well known in London for the specimens had sent home. His beagle voyage is credited for providing him with the seeds for his evolution theory that he would spend the rest of his life working on. 
• Darwin was also influenced by 3 earlier thinkers. The first is Jean Lamarck who was one of the first scientists to propose that species change over time. However, he was wrong about how species change with his belief that traits an organism develops during its own lifetime can be passed onto offspring. Additionally, Charles Lyell’s book Principles of Geology was taken by Darwin with him on the Beagle. In the book, Lyell claims that the Earth is much older than people believed. Lastly, Thomas Malthus wrote an essay titled On population. In this he argues the population is kept in check by killing off the weakest members when a population gets too large and...

My AP Biology Thoughts

Episode #2

Welcome to My AP Biology Thoughts podcast, my name is Jacqueline and I am your host for Episode 2 called the Natural Selection Mechanism. Today we will be discussing the 5 components of the mechanism, and how they ultimately lead to evolution.

• Natural selection, as you probably already know, is the process in which organisms who are better adapted to their environments and have higher fitness pass on their traits to offspring. It is a driving force of evolution, which is the change in the genetic and allele frequencies in a species' gene pool over time. Charles Darwin and Alfred Wallace were the co-discoverers of the theory of Natural selection, although Darwin is most often credited as the sole contributor. Natural selection may be one concept, but it is a broad one, and it can be split into five major components: overpopulation, variation, competition, fitness, and reproduction. These five make up what is known as the natural selection mechanism.

• As I explain the natural selection mechanism, I’ll be using the example of Canada geese. Let’s start with overpopulation. Overpopulation is the occurrence where a species’s population increases beyond its habitat’s carrying capacity. It is the rather simple first step of the mechanism, but it sets up a chain reaction of more complicated events. Let’s say the population of Canada geese living in a lake habitat has grown to the point where their aqueous plant food source has become limited and can no longer sustain all of them. Overpopulation has occurred.
• One side effect of overpopulation and the second mechanism of natural selection is variation. As more members of a species are born, the genetic and physical variance in that population will increase. This occurs often due to random mutations, which can introduce new traits into populations. It may also happen because of immigration of another population (of that same species) but with different genes into the area, known as gene flow. Basically, more members of a species means more variation of genotypes and phenotypes in the population. A wider array of different traits will be developed among them, some of which may convey advantages or disadvantages for the organism. Now let’s say that the Canada Geese population, which is experiencing an influx in birth rate (AKA overpopulation, the first part of the mechanism), is also more likely to have random mutations, which will lead to increased variation of traits. Short, medium, and long necks are all now traits prevalent in the species.
• Another side effect of overpopulation and the third mechanism of natural selection is competition. When there are too many organisms and limited resources, individuals of a species must fight the others around them for those necessities, or risk dying out. However, only the most adept will be able to survive and ultimately reproduce. This ability is known as fitness, and it is the 4th mechanism of natural selection. Being able to outcompete the competition and survive to reproductive age to pass on one’s genes is the prime signifier of greater biological fitness. These individuals often have advantageous genes or traits that give them a leg up against rivals and are more likely to be inherited by future generations. The Canada geese population has breached carrying capacity and now has too small of a plant food source for too large of a group. The geese begin to compete among themselves for the resource. The geese with the trait of longer necks have greater fitness because they are able to reach the plants easier and outcompete those with shorter necks, who die out before reproduction. The surviving long-neck geese reproduce and are officially deemed more fit.
• Reproduction is the final component of the...

Welcome to My AP Biology Thoughts podcast, my name is Saarim and I am your host for episode #1 called Darwin’s Early Life. Today I will be discussing the early life, academia, and internal turmoil of English naturalist Charles Darwin, who is notable for his scientific theory of evolution by natural selection. We all know the name, Charles Darwin, and his idea that all living things developed and adapted overtime as a result of random mutations which gave these organisms traits suitable for their lifestyles. But how did he come up with this idea? The impacts of his theory are enormous as they really show us where all living things come from and the theory even created divisions in society amongst Darwinists/modernists and fundamentalists. But let's go all the way back to explore the origins of this theory.

• Talking about Darwin in Academia, his experiences in school, transition from medicine to religion, to naturalism and voyage on HMS Beagle, observations from trip/significance, and internal struggle deciding to publish work
• Credit New England Complex System Institute and Eric Guise’s AP Biology videos for the following info
• Darwin Info
• Born in Shrewsbury, England; attended Shrewsbury School
• Interested in nature since young age - beetle collection
• Father wanted him to be doctor - went to Edinburg Medical School - found lectures boring and couldn’t stand watching surgeries done without pain killers (left med school after 2 years)
• Father arranged from him to be priest/clergyman - earned bachelor of arts degree from Cambridge; continued interest in nature
• Became friends with two professors at Cambridge - geologist and John Henslow (botanist)
• Around the world sailing trip on HMS Beagle being arranged by Royal Navy - John Henslow recommended Darwin as the trips naturalist
• Darwin left for a 5 year journey - wrote down all his observations, etc. 

• Brazil
• Visited tropical rainforest: great diversity - began thinking about diversity of life and the creation of different species
• Observed animals eating and chasing each other - animals struggled to survive

• Argentina
• Observed how the grass where the cattle grazed smaller than grass that cattle had been introduced with - idea of something allowing different types of grass to survive

Welcome to My AP Biology Thoughts podcast, my name is Diana along with Sofia and Saahith and we are your hosts for Unit 7: Examples of Evolution-The Three Toed Skink- and I know what you’re thinking…. nope this is not derogatory or a slur. In episode 117, we will be discussing the species the Three Toed Skink and how it relates to the AP Biology Curriculum. We want to thank our sources for the information presented in this podcast episode today which include Reptiles Magazine, National Geographic, Eurekalert.org, syfi.com, phys.org, and sciencedaily.com. You can find the citations and links to these sources in the show notes.

The three toed skink, aka Saiphos equalis, is found in eastern Australia, primarily in New South Wales and Queensland. The three-toed skink is sometimes mistaken for a snake, eats crawling insects and worms, and is active at night. The three toed skink is a “bimodally reproductive species” WHATS THAT this means that some lay eggs and some give birth. Dr. Whittington, from the School of Life and Environmental Sciences and Sydney School of Veterinary Science at the University of Sydney in the article “Biologists observe a three-toed skink lay eggs and give birth to a baby,” says, “Put in the context of evolutionary biology, being able to switch between laying eggs and giving live birth could allow animals to hedge their bets according to environmental conditions." There are at least 150 evolutionary transitions from egg-laying to live-bearing in vertebrates. To elaborate on this, Sofia will share the interesting evidence of evolution of the Three Toed Skink.

Thank you, Diana, for that beautiful introduction to our beloved skinks. In the article, “Which Came First, the Lizard or the Egg”, Dr. Camilla Whittington from the University of Sydney skink research team describes how the earliest vertebrates were egg-layers, but that over thousands of years, embryos remained inside their mother’s for longer, until some began live births. WHAAAAATTTT?? The Three-toed skinks are an example of a species that have evolved to perform both reproduction methods of egg-laying and live births. Get yourself a skink who does both. Direct observation studies have revealed that the skink species located on the warm weathered coasts of New South Wales lay eggs rather than performing live birth. On the contrary, the skinks located in the cold

Welcome to My AP Biology Thoughts podcast, my name is Shrithik Sekar, Kyle Mason, Gabe Moriello, and I am your host for Unit 7: Examples of Evolution, Darwin’s Finches. In episode 116, we will be discussing this topic and how it relates to the AP Biology Curriculum. 

“We want to also thank our sources for the information presented in this podcast episode today which include (Britannica, Galapogosisland.org, and Crash course Biology on Youtube). You can find the citations and links to these sources in the show notes.”

 What are Darwin's finches? 

• Who is darwin? - Geologist and Biologist, who formed the theory of natural selection. Known for his contributions to Science of evolution. He studied many finches which were found in the galapagos islands located 1,000 km off the coast of Ecuador 
• What were the finches? - These finches were a Group of 18 different species found in the Galapagos island. Darwin found the finches were all closely related with small direct observations that he made during his time in the Galapagos islands 
• What did he study? -During his studies while in the Galapagos islands, he concluded the speciation of the finches which is known as the experiment of Darwin’s finches  
• How does it relate to evolution? - It relates to evolution because it is an example of Direct observation 

 Connection direct observation evolution 

• What is direct observation of evolution? - Through observation, in small population sizes, it can be found many changes of one species to then create many subspecies. Through direct observation of evidence in almost every species. THis idea had to do with the last universal ancestor, how all species are alike in many ways and all stemmed from the same ancestor. These finches dna is super similar, but these small differences of dna created a difference in appearance which was found ny darwin. 
• ( This begs the question of ) Why are the finches an example of evolution? All 18 species of Darwin’s Finches were originally one finch species on the coast of south america. However, Darwin discovered that this species branched off into 18 different species on the Galapagos islands depending on the finches’ environment 
• What Key pieces of evidence did darwin find? - Darwin found the difference, fruit eating finches had wide beaks, insect eating finches had narrow beaks, and based on different factors of each finches environment each species had a different characteristic change. - GO TO Image 

Keenan: Welcome to My AP Biology Thoughts podcast, my name is Keenan Wallace and I am your host for this podcast. In episode 115, we will be discussing the topic of Coywolves and how they relate to the AP Biology Curriculum. 

Keenan: For this episode, we’ve brought in Alex Profit and Serena Russel to discuss the evolution of coywolves. So, to start us off: what exactly is a Coywolf?

Alex: Well, ‘Coywolf’ is actually just a nickname for what is known to the scientific community as an eastern coyote. Eastern coyotes are hybrids of coyotes, wolves and dogs, however they are still primarily coyotes and remain as coyotes rather than wolves. 

Keenan: So you say that the Coywolves, or eastern coyotes are a mix of several different species. Do you know the genetic breakdown?

Serena: It’s difficult to say for certain since the coyotes’ genetic makeup varies by region and population, but according to a DNA analysis done by Evolutionary Biologist Javier Monzón, they are 64% coyote, 13% gray wolf, 13% eastern wolf, and 10% dog. 

Keenan: Wow, that’s some genetic diversity. So how do these new hybrids differ from their pure coyote ancestors?

Alex: For one thing, they’re larger. Eastern Coyotes are 35-37% larger than their western counterparts. They also have larger and more powerful heads, their ears are more rounded like a wolf’s and they have wolf-like fur markings. There’s lots of variation within and between populations, but coywolves' features tend to match the midpoint between coyotes and wolves. 

Keenan: Fascinating! So from what I understand, this interbreeding is a fairly recent development. What led to it?

Serena: This story started several hundred years ago with the arrival of Europeans in the Americas. When Europeans colonized the East Coast of America they started cutting down forests and hunting large prey in the region, which threatened the habitat and food source of local grey wolves. At the same time, western coyotes, which are adapted to more open terrain, were drawn east by the expansion of their preferred habitat via deforestation. With shrinking numbers of grey wolves and a new thriving population of coyotes in the region, it makes sense that the wolves soon turned to coyotes as mating partners. 

Serena: From there, natural selection took over. With the right mix of coyote and wolf DNA, a new species was created that was the best of both worlds. These “coywolves,” as they are called, are larger than coyotes, but inherited the social nature of wolves, meaning they form packs to hunt, which allows them to hunt large animals like deer in addition to the small prey that coyotes usually feed on. On top of that, they possess the strong ability of coyotes to adapt to urban environments, and are comfortable in both open and forested environments. 

Keenan: I can see why this mixing would be beneficial, but is it considered evolution, or just hybridization? 

Serena: Both....

Anushka Agarwal, Olivia Lundquist, & Hana Hamid 

Welcome to My AP Biology Thoughts podcast, our names are Anushka, Olivia, and Hana and we are your hosts for Unit 7: Examples of Evolution-Butterflies and parasites. In episode 114, we will be discussing Butterflies and parasites and how they relate to the AP Biology Curriculum. 

•  To start off, what is evolution? Evolution is the process by which different organisms develop from their ancestors to adapt to the environment they are living in. This idea was proposed by Charles Darwin to explain how species have the ability to evolve. We can look at the Blue Moon butterflies for examples and how they adapted to their environment to protect themselves from the killing parasite. The Blue Moon Butterfly, or Hypolimnas bolina, is an eggfly commonly found in New Zealand, Australia, New Guinea, Solomons, etc. The blue moon butterfly’s mating season is normally in the spring and summer. Their name is derived from the 2 bright circular patches on the backs of the males. Natural selection occurring between the butterflies and parasites is an example of evolution happening in real time. This is because scientists discovered that the bluemoon butterflies developed resistance in a span of 10 generations (which lasted a year). 
• Additionally, the peppered moth is a species of a night-flying moth which is most commonly found in the northern hemisphere in countries such as Europe, Asia, and North America. They are generally small moths (only 1.5-2.5 inches) and their eggs normally hatch during mid summer. While some moths are typically light in color, many have dark skins and normally have extra camouflage to protect them from their predators (which includes ​​flycatchers, nuthatches, and European robin). We can see a difference in the colors of the peppered moth due to the Industrial Revolution marked an era of industrial change in Europe and the United States from 1760-1840, which affected not only economy but the environment as well. 

•  mutation
• the changing of a structure of a gene that may result in a variant form → can have impact bc it has the potential of getting passed down that leads to evolution
• mutation: males can survive the infection of parasite that kills male embryos
• normally they cant(mutation allowed for them to live and complete term/live)
• Natural selection (blue moon butterflies) 
• Since the parasites normally targeted male blue moon butterflies, their population was a staggering 1%. However, because these butterflies obtained immunity from the parasite, their population bounced back to 40% in less than a year! 
• natural selection

Welcome to My AP Biology Thoughts podcast, I am Emily Greenberg and I am Angelina Graf and we will be your hosts for “Unit 7 Heredity: Examples of Evolution-antibiotic resistance”. In episode 113, we will be discussing antibiotic resistance and how it relates to the AP Biology Curriculum. 

• Antibiotics are drugs that fight infections that are caused by bacteria
• Antibiotic resistance is when bacteria and germs build up resistance to the medications that are meant to kill them
• Antibiotic resistant germs are often very difficult to treat and dangerous infections can emerge
• A common misconception is that antibiotic resistance means that the body is resisting antibiotics, however it is actually the bacteria that is becoming resistant to antibiotics
• Overuse of antibiotics is one of the main causes of antibiotic resistance

• Antibiotics also kill good bacteria that help to protect the body from infection
• Antibiotic resistant germs can spread throughout healthcare facilities, the environment, and other communities.
• The action of an antibiotic is an environmental pressure 
• Species have to adapt and evolve in order to survive these pressures
• We know that evolution is happening because bacterial infections can continue to spread even with the presence of antibiotics
• Penicillin resistance: 
• In WWI, penicillin treatment was used to treat the wounded and by some smaller civilian populations
• Biochemists began reporting resistance to it before the war was over and found a penicillin-inactivating enzyme secreted from a particular bacteria.
• Over the next few decades, overuse and repeated exposure to antibiotics helped the selection and replication of antibiotic resistant strains of bacteria

• Antibiotic resistance evolves as a result of natural selection and genetic mutation
• Bacteria that develop mutations that are resistant to antibiotics are more likely to survive and reproduce; this means that they are more fit
• If resistant bacteria reproduce with other resistant bacteria, their offspring will be fully resistant and this trait will become more frequent in the gene pool

Welcome to My AP Biology Thoughts podcast, my name is Stefanie Ribecca and I am your host for episode # 104 called Unit 5 Heredity: Chromosomal Inheritance. Today we will be discussing how inheritance occurs in the chromosomal level. 

• Chromosomal inheritance is an extension of Mendelian genetics. 
• Chromosomes contain DNA which carry the genetic information that code for proteins. 
• Chromosomes are found in pairs, and increase genetic variation during meiosis.

• During meiosis, non sister chromatids in homologous pairs exchange information during crossing over.
• Certain genes may be close together on the chromosome and may appear to be inherited together. 

• Chromosomal inheritance allows for a combination of traits from both parents. 
• Genetic diversity from chromosomal inheritance allows individuals in a population to adapt to the environment. 

Thank you for listening to this episode of My AP Biology Thoughts.   For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.  

• "Ice Flow" Kevin MacLeod (incompetech.com)
• Licensed under Creative Commons: By Attribution 4.0 License
• http://creativecommons.org/licenses/by/4.0/

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Welcome to My AP Biology Thoughts podcast, my name is Sid and I am your host for episode #112 called Unit 6 Gene Expression and Regulation: Biotechnology. Today we will be discussing how we use technology to study how the mechanisms of DNA and gene expression work.

The four main processes used in biotechnology that relate to this unit are bacteria transformation, PCR, electrophoresis, and DNA sequencing. Bacterial transformation makes multiple copies of a recombinant DNA molecule. PCR is used to produce millions of copies of a DNA sequence from an initial sample. Electrophoresis separates DNA and RNA molecules by their size and their electrical charge. DNA sequencing is used to determine the sequence of the bases in a DNA molecule.

• First we’ll talk about bacterial transformation. The process of bacterial transformation starts with mixing the prepared bacteria with DNA. Then the bacteria are heat shocked. This allows them to take up a plasmid. The bacteria that take up the plasmid become resistant to antibiotics, so we place all of the bacteria on an antibiotic plate. The ones that survive are the ones that are known to have taken up the plasmid since they survived the antibiotic. The bacteria without the plasmid end up dying. The bacteria that survived end up being used to create a cluster of identical bacteria that also contain the plasmid. The colony containing the plasmid is grown and used to produce the plasmid or proteins.
• Another form of biotechnology is PCR. To begin, the main ingredients (taq polymerase, primers, template DNA, nucleotides, and cofactors) are all added in a tube. The first step of PCR is denaturation. In denaturation the reaction is heated so that the DNA strands separate and create single strands. The next step is annealing where the reaction is cooled so that the primers bind to the complementary sequence on the DNA strands. The third step is extension. In this step the temperature is raised again so that the taq polymerase starts at the primers and synthesizes new strands of DNA. This cycle repeats between 25-35 times which ends up creating millions of copies of the same DNA region.
• Electrophoresis is another form of important bio technology. In electrophoresis, DNA samples are placed into indentations at one end of a gel. THis gel gets an electric current applied to it. Since DNA fragments are negatively charged, they move towards the positive electrode. Because the DNA fragments have the same charge, the smaller fragments are able to move through the gel faster than the large ones. This allows the DNA to be separated by size. The gel is then stained with a DNA binding dye which makes the DNA fragments appear as bands so that they can be observed.
• The last thing we are going to talk about is DNA sequencing. In DNA sequencing, the DNA strand goes through bacterial transformation so that we can produce many copies of it in a plasmid. The DNA is then isolated and goes into a plate with other ingredients like the DNA bases, DNA polymerase, primers, and modified bases labeled with colored fluorescent tags called terminator bases. This mixture then goes through a process very similar to PCR. The difference is when polymerase...

Welcome to My AP Biology Thoughts podcast, our names are Olivia, Anushka, Mea, and Hana and we are your hosts for the Unit 8 Ecology-the Isle Royale Study podcast. Today we will be discussing the Isle Royale Study and how it relates to the AP Biology Curriculum. 

• Camping —> DOCTAH guise —-> isle royale —-> us listening to him talk :)

• Winter controls the ticks (kills them all if cold temperature) 
• Provide ex of trophic cascading 
• Predator prey talk abt it
• Human interaction/interference (trails, being on/off) 
• Coloring of the wolves 
• Talk abt winter study (break island into quadrants and take populations #’s) 

• Predator-prey relationship:  
• Trophic structure: a flow of energy between organisms in an ecosystem 
• Energy flow 
• Parasitic 
• Importance of genetic diversity

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. 

• "Ice Flow" Kevin MacLeod (incompetech.com)
• Licensed under Creative Commons: By Attribution 4.0 License
• http://creativecommons.org/licenses/by/4.0/

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Welcome to My AP Biology Thoughts podcast, my name is Arthur Kim and I am your host for episode # 111 called Unit 6 Gene Expression and Regulation: Mutations. Today we will be discussing what genetic mutations are, the different types, as well as some of the possible effects.  

•  A mutation is any change to a sequence of DNA.
• They’re not always bad, as some mutations can arise that result in a more favorable phenotype.
• Mutations can also occur on the scale of chromosomes, often as a result in errors in meiosis.

•  On a strand of DNA, there are two main types of mutations that can occur.
• Point mutations are the result of swapping one base pair for another.
• Very often, these aren’t a big deal because only one amino acid will be affected or possibly unaffected since oftentimes more than one codon produces the same amino acid. In many cases, the protein that the mutated strand codes for will still be functional.  
• Frameshift mutations are the result of an insertion or deletion of a base pair in a strand of DNA.
• These are often detrimental because they completely change the codons in an entire sequence of mRNA. As a result, the protein will be synthesized with completely different amino acids than what they’re supposed to be.  
• This causes the protein to be nonfunctional.
• Frameshift mutations are the cause of several deadly genetic diseases such as Tay Sachs and cystic fibrosis.  
• At the level of chromosomes, the types of mutations that can occur are deletions (part of the chromosome is lost), duplications (an extra copy of a part of a chromosome), inversions (the orientation of a segment of a chromosome is flipped), and translocation (two chromosomes exchange components).  

•  Genetic mutations are one of the main sources of variation within the gene pool. As a result, mutations are what allow for evolution to occur in populations, bringing about the diversity of life on Earth we see today.  

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. 

Music Credits:

• "Ice Flow" Kevin MacLeod...

Welcome to My AP Biology Thoughts podcast, my name is Shriya Karthikvatsan and I am your host for episode #110 called Unit 6: Gene Expression and Regulation. Today we will be discussing the mechanisms used by cells to increase or decrease the production of specific gene types, and how this fits into the overarching unit. 

• We will begin by going over a few helpful terms and ideas to provide context for the topic of gene expression and regulation which is a pretty broad topic as a whole
• A gene consists of a string of DNA hidden in a cell’s nucleus, and what we will unpack is how it knows when to express itself and cause the production of a string of amino acids called a protein
• The overall process is that a string of DNA is expressed to make RNA
• Then, something called mRNA is translated from nucleic acid coding to protein coding to form a protein 
• In terms of regulation, genes can’t control an organism on their own so they must interact with and respond to the organism’s environment 
• Some genes are always “on” regardless of environmental conditions, and these genes are among the most important elements of the genome because they control the ability of DNA to replicate, express itself, repair itself, and perform protein synthesis
• Overall, regulated genes are needed occasionally and get turned “on” or “off” 
• Regulation differs between prokaryotes and eukaryotes because in prokaryotes, most regulatory proteins are negative and turn genes off 
• In eukaryotes, cell-cell differences are determined by expression of different sets of genes
• This means that an undifferentiated fertilized egg looks and acts quite different from a skin cell, a neuron, or a muscle cell because of differences in the genes each cell expresses 
• In the next segment we will go into further detail of the specific processes involved in expression and regulation 

• Gene expression begins with transcription which makes mRNA and the overall process is the same in both prokaryotes and eukaryotes 
• Prokaryotes lack a nuclear envelope, and eukaryotes use an extra step called RNA processing where RNA is edited and introns are edited out and exons are spliced together
• It is catalyzed by RNA polymerase which separates DNA strands and links RNA nucleotides at the 3’ end (side notes: prokaryotes have 1 type of polymerase and eukaryotes have 3)
• Transcription is initiated when RNA polymerase binds to a promoter and unwinds the DNA strands
• Initiation site and a small sequence after are recognized by transcription factors which are...

Welcome to My AP Biology Thoughts podcast, my name is Helena Holley and I am your host for episode #109 called Unit 6 gene expression and regulation: Regulation of gene expression. Today we will be discussing the mechanism of gene expressions and regulation in Eukaryotes and Prokaryotes.

 Gene expression and its regulation and control is essential for cell specialization in Eukaryotes. All cells have the same information, however their differences in function come from which genes they express. As you go through development cells are differentiated. The way this happens is by specific transcription factors and translation controls that tell the cells which genes they are expressing as you develop. Your basic genetics are not the only thing that determines which genes are expressed, epigenetics also plays a role. Certain environmental factors that occur in a parents lifetime can alter the gene expression of offspring. This happens when there are changes in the parents' cells that undergo meiosis to produce gametes. Examples of this include DNA methylation and histone modification. While I was just discussing eukaryotes above, gene expression and regulation is also important in prokaryotes, which I will discuss more later. 

There are various ways in which gene expression is regulated in Eukaryotes. One regulation method is determined by how tightly DNA is wrapped around Histone proteins. The tighter the DNA is wrapped, the harder it is for transcription to take place, and certain enzymes can alter how tight or loose it is wrapped depending on what needs to happen. There are also chromatin-modifying enzymes that can make the DNA more or less accessible. Another regulatory factor is the Control elements which are regulatory sequences on DNA that control the expression of proteins. Alternative RNA splicing helps to regulate post transcription, as it produces different mRNA from the same gene. Another useful method is mRNA degradation which is used to break down mRNA if the protein is not needed to be expressed anymore. Finally, various regulatory proteins can block initiation of translation if that is needed. It is important to note that mRNA is not the only type of RNA used for regulation, and there are various types of non-coding RNA that have different functions in regulation of gene expression. In prokaryotes there are repressible and inducible operons. The repressible operon genes are able to be silenced, and the inducible operon genes are able to be turned on. This function of these operons is important in gene regulation because if a repressible operon is absent, the repressor is inactive and the operon will be produced. When too much of a repressible operon is in the cell, it will bind to the repressor which will bind to the operator, preventing any more from being produced. For inducible operons, the process works essentially the opposite of the repressible operons (so briefly the repressor is active when there is an absence of lac operon, and it is inactive when there is presence lac operon). 

Gene expression and regulation is important because any errors in regulation can lead to developmental problems. For example, If the tumor suppressor...

Welcome to My AP Biology Thoughts podcast, my name is Saarim Rizavi and I am your host for episode #108 called Unit 6 Gene Expression and Regulation: Translation. Today we will be discussing everything there is to know about translation. I will first be giving a brief overview of what translation is, it’s overall function, the 3 steps involved in translation, and some of the different components and organelles involved in translation. I’ll then go into greater detail on the individual steps of translation which will involve the organelles and different components mentioned before. Finally, I will relate the process of translation to the broader topic of gene expression and regulation. Before I begin, I would like to give credit to Khan Academy, biologydictionary.com, and nature.com for the information they provided me with in order for this podcast to be possible. So thanks to them. Alright, so here we go:

• Translation is the process of creating proteins from an mRNA template
• A cell reads information from mRNA molecules and uses this information to build a protein - involves decoding an mRNA and using its information to build a polypeptide, and multiple polypeptide chains form a protein
• Three basic steps of translation - initiation, elongation, and termination
• Initiation - the ribosomes get together with the mRNA and the first tRNA so translation can begin
• Elongation - the amino acids are brought to the ribosome by tRNAs and linked together to form a chain of amino acids
• Termination - the finished polypeptide is released to go and do its job in the cell
• In mRNA, the instructions for building a polypeptide come in groups of 3 nucleotides called codons - there are 61 codons for amino acids and each of them is read to specify a certain amino acid out of the 20 possible amino acids
• Stop codons tell the cell when polypeptide is complete and the AUG codon is the start codon which signals the start of protein construction
• In translation, the codons of an mRNA are read in order, from the 5’ end to the 3’ end, by tRNAs.
• tRNA’s = molecular bridges that connect mRNA codons to the amino acid they encode
• One end of the tRNA has a sequence of 3 nucleotides called an anticodon, which binds to a matching mRNA codon through base pairing; the other end of the tRNA carries the amino acid specified by the codons
• tRNAs bind to mRNAs inside the ribosomes - ribosomes are made up of protein and ribosomal RNA
• The ribosomes provide a set of slots where tRNAs can find their matching codons on the mRNA template and deliver their amino acids. As these tRNAs enter slots in the ribosome and bind to codons, their amino acids are linked to the growing polypeptide chain in a...

Welcome to My AP Biology Thoughts podcast, my name is Chloe McGregor and I am your host for episode #107 called Unit 6 Gene Expression and Regulation: transcription and RNA processing. Today we will be discussing the process of transcription, and how MRNA is processed on its way to the ribosomes. 

•  The central dogma is the process by which the genetic information stored in DNA is converted into functional products such as proteins. This process consists of 3 steps: transcription, translation, and protein synthesis. In this episode, I will specifically discuss transcription, the process of transcribing shorter segments of DNA into mRNA strands. However, once these mRNA strands are created, there are still steps that take place to ensure that the strand is mature and ready to be translated. This is called RNA processing. The mRNA strand is manipulated into a mature strand through a series of processes, and is then ready to travel to the ribosomes for translation and protein synthesis.

•  As I mentioned earlier, transcription is the first step and this is when the DNA strand is read, and a new complementary mRNA strand is synthesized. DNA is composed of different nitrogenous bases compared to RNA. DNA consists of adenine, thymine, cytosine, and guanine. However, RNA contains uracil instead of thymine. Base pairing rules are used by RNA polymerase to synthesize a new strand using the information on the unzipped DNA strand. Transcription is very important because DNA is very unique and one of a kind, so this single strand of RNA makes it possible for the genetic information to stay safe, but also be used for protein synthesis outside of the nucleus. Following transcription, RNA processing occurs. Premature mRNA strands contain both introns and exons that are transcribed from the DNA, however, the introns are spliced out to create a concise and mature strand of RNA that is ready to be translated. Introns are removed to ensure that the correct protein is being created during protein synthesis because a mistake in the RNA strand can cause mistakes during translation. Also, if introns are kept on accident, the wrong protein can be produced which will disrupt many different cellular processes. RNA splicing is also the reasoning behind one strand of DNA coding for so many different proteins depending on which introns are spliced out, and which exons are kept in the sequence. 

•  Transcription and RNA processing play a major role in healthy cellular function and bodily function in general. Because specific proteins and enzymes are so vital to so many different processes that are happening simultaneously, it is important that transcription and RNA processing are happening precisely and efficiently to keep the body functioning. The idea of RNA processing is also important because it can provide different proteins from the same gene depending on what the body is in need of. Overall, these processes may seem small, but they play such a large role in kickstarting protein synthesis and making sure that the RNA strands are accurate and ready to be converted into proteins. 

Welcome to My AP Biology Thoughts podcast, my name is Morgan and I am your host for episode # 106 called Unit 6 Gene Expression and Regulation: DNA Replication. Today we will be discussing the process by which cells replicate their DNA

•  Difference between prokaryotic and Eukaryotic DNA
• P is one circular piece of dna where eukaryotic are multiple linear chromosomes
• DNA replication is semi-conservative
• Double helix is split in two and then each new strand is synthesized so to new double helices are made, each with one old and one new strand 
• very complex but very fast
• Extremely accurate (only 1 in a billion bases are messed up)
• Have to prime the DNA for replication
• Primers are short molecules that attach to the dna at the origin of replication 
• Mde by the enzyme primase
• Helicase is the enzyme that unwinds the double helix- initiates the replication fork (where two strands split apart)
• Multiple replication forks in eukaryotic dna
• Topoisomerase checks problems in the DNA before replication and maintains the structure
• DNA polymerase is the enzyme that synthesizes the new DNA strand- reads the bases and matches up complementary nucleotides

•  Replication initiation can occur at both directions from the origin where the primer binds
• DNA polymerase can only add nucleotides in the 5 to 3 prime direction, and read the strand of dna in the 3 to 5 prime direction
• Leading strand is continuous
• Lagging strand is discontinuous, has to read and synthesize in short segments (okazaki fragments)
• Enzyme ligase seals together the fragments
• Energy needed for this process (remember forming bonds between the nucleotides requires energy) 

•  Connection to mitosis
• S phase of mitosis is dna replication
• Necessary for cell division to make the same amount of chromosomes in...

Welcome to My AP Biology Thoughts podcast, my name is Jacqueline Sun and I am your host for episode #105 called Unit 6 Gene Expression and Regulation: DNA and RNA Structure. Today we will be discussing the central structural components of DNA and RNA as well as the similarities and differences between the two.

•  Deoxyribonucleic acid, DNA, and ribonucleic acid, RNA, are two of the most important biological molecules for survival
• DNA responsible for carrying genetic information is commonly considered the “blueprint” for life’s functions. Its basal structure, a double helix that is unique from RNA, is key to its ability to replicate itself. DNA, when not undergoing replication, is coiled up into compact structures known as chromosomes. They are wrapped around histone proteins: the degree of tightness to which they are wrapped determines how much of the DNA is expressed.
• RNA builds off of DNA and creates a template from which proteins can be created in ribosomes. Because they are based off of a parent DNA strand, RNA has a single strand instead of two.

•  However, there is much more to DNA and RNA Structure than the helical strands.

Lets first focus on what makes up the strands for DNA and RNA:

• Both DNA and RNA have a sugar-phosphate backbone that is key to holding the entire molecule together. 
• However, the sugar in DNA is deoxyribose sugar, from which it derives its name. The sugar in RNA is ribose sugar, which has one more hydroxyl group than the sugar in DNA. 
• The sugar and phosphate group in DNA and RNA alternate repeatedly. They link with a special directionality that is often denoted with a 5’ and 3’ end. This is a rather abstract concept, but basically the 5’ and 3’ indicate which carbon in a sugar molecule the phosphate group will attach itself, forming the repeating phosphate-sugar backbone.
• Another central structural component are the nitrogenous bases found in both DNA and RNA, with one key difference.
• DNA has the bases adenine, cytosine, guanine, and thymine. Adenine and guanine are known as purine bases, while cytosine and thymine are the pyrimidine bases. Purines tend to be larger than pyrimidines because purines have a double ring structure as opposed to pyrimidine’s single ring structure.
• Only purines and pyrimidines can bind together. Specifically, in DNA, adenine and thymine bind together, while cytosine and guanine bond together. They are held together by hydrogen bonds which link not only the bases, but also the two strands of DNA to form a double helix. The 1:1 ratio by which the nitrogenous bases bond (adenine=thymine, guanin=cytosine) explains how DNA molecules are able to replicate by synthesizing a new strand from a parent...