Module 8

 

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Enjoy this funny meme I found online while reading about genetic variation!

Genetic variation is the differences in DNA between individuals or populations and is caused by genetic drift, genetic recombination, mutations, and more. This process is something that is important for a population because having different alleles and DNA allows for a population as a whole to adapt, thrive, and evolve. The evolution of the population is a success in terms of science. If we didn’t have some genetic variation, a population would likely struggle if a disease swept in. We could also see problems with potential inbreeding if there wasn’t any variation in a population. We learned in a previous module the nasty side effect of inbreeding.

Even with this information, it is still assumed that selection eliminates genetic variation. However, genetic variation does not erode over time. How can genetic variation be present continuously in populations even though the selection is happening? Perhaps, it’s the mutation aspect of this situation. This is something that constantly occurs in life and is randomized. We will always see a new mutation from some species or population, and it ensures that there will thus always be at least some genetic variation. We can also see genetic drift and genetic recombination having a hand in this as well. Genetic drift is the variation in the frequency of different genotypes in a population, granted, this would only be a factor in smaller populations. Genetic recombination is the rearrangement of the DNA sequences. This ensures a difference in sequences within a population, thus, a variation in genetics. Overall, even though selection occurs within a population, there will always be some form of genetic variation. 

Half-way Mark

 

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I can’t even begin to believe that we are halfway through this class and the very last semester of my undergraduate degree. It feels like I should still be a freshman in college going through the introduction classes of my major and minors. I feel like I have learned a lot throughout this semester and yet when I try to grasp the recently learned information, I can’t for the life of me even begin to describe what that information is exactly! I blame it on senioritis. I learned in this class that evolution is such a broad concept that I probably will never truly grasp every single part under this umbrella term. I remember being in the fourth week of the semester and having evolution and natural selection just click in my head. I had always had a decent understanding of these concepts, but it just never really clicked in any of my science classes until now. A part of me felt stupid for it taking 4+ years to get to this point but another part of me was proud of myself for getting to where I am.

If I go back to my original post, I don’t think I would change anything about my definition of evolution just yet. I am expecting that to change by the end of the semester. But, I feel like my definition was broad enough to allow what I have learned thus far to fall under the original definition. My understanding hasn’t really changed. I have just come to the conclusion that I don’t know everything about evolution yet.

I am struggling more so with R exercises than the concepts we are learning in class. It’s very irritating because it’s not something I have ever done before and may not ever do again in my academic career. I just have to learn to be patient with the exercises and myself and know that it’s okay to ask for help.

I am curious about COVID-19 and what makes these strains of the coronavirus any different than what we have seen before. Why is it that some bodies have a difficult time identifying this virus as dangerous and not reacting quick enough to fight back? I want to learn more about how evolution affects everyday life that I would have an easy time relating to as a college student studying science. It’s hard to understand concepts if you don’t have anything to relate them to in your life.

Inbreeding

 

Blog Post Module 6: Reflection Prompt

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Inbreeding

 

Inbreeding is a common phenomenon in natural populations. This phenomenon occurs when two closely related organisms mate with each other, producing offspring. Inbreeding can change the distribution of genetic variation among the populations of plants and animals. Though we have information on how inbreeding can affect evolution and can identify the costs and benefits in the populations of plants and animals, we still don’t know everything about the forces shaping the evolution of nonrandom mating in general.

Inbreeding can lead to the evolution of assertive mating. Assortative mating is simply a mating pattern where similar phenotypes are mated with another more often than what is generally expected with random mating. With inbreeding within a population, we would see an increase in the ability for the parent to potentially pass on favored traits to their offspring and therefore we eventually will see a fixing of those favored or desired traits. We would also see an increase in uniformity to a species. In terms of evolution, inbreeding could increase the rate of evolutionary change. It can also increase the rate that natural selection can eliminate unfavorable deleterious alleles from a population. On top of all this, we could expect to see a higher fitness that can theoretically allow the organism to survive and mate with more success than other organisms.

Some costs of inbreeding can be seen in natural populations of animals and plants as well as humans. With inbreeding, we can see an increase in undesirable genes and a reduction in the diversity of the genes. An example of inbreeding in Europe that is well-known concerns, royal families. It’s been a centuries-long practice to marry within the royal family in Europe. The many marriages between first cousins led to a high rate of hemophilia among the members of the family. Another example would be the many, many health issues King Charles II of Spain. In animals, we see evidence of inbreeding in feral sheep on a small island off the coast of Scotland. Inbreeding can cause lower fertility rates and lower “vigor” in organisms. We can see fewer offspring and higher offspring mortality. Overall, inbreeding can cause birth defects, both physical and non-physical defects.

Mutation Rates

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Do you think mutation rates evolve? Explain your answer in the context of Darwin's postulates about natural selection!

I believe mutation rates evolve over generations. We see mutations as a fundamental factor in evolution as it allows for genetic variation that natural selection can act upon. Changes in genetics can lead to a change in mutation rate. Charles Darwin’s postulates is a theory stating that natural selection is the major cause of evolution. Each of his postulates can be tested.  These postulates are: “Individuals within species are variable” “Some of these variations are heritable” and “Individuals that reproduce more successfully are those with the favorable gene variations”. These postulates pertain to variation among individuals and over generations. It hits close to how mutations work as they are the cause for the variations in genes among individuals in a population. Additionally, Darwin’s ideas of evolution and change over generations promote the evolution of mutation rates. Overall, since the mutation is a key factor in natural selection and evolution, it is safe to assume that mutation rates can evolve.

 

Under what circumstances do you envision high or low mutation rates to be adaptive?

In terms of viruses and bacteria, our mutation rates evolving all the time. The mutation rates change in response to pressures. An evolved mutation rate can allow the bacteria or viruses to quickly produce mutations for survival. This would be an example of high mutation rates. The virus needs to change quickly for survival and a high mutation rate could mean it is more successful than other viruses and lead it to reproduce more so than others, leading to an adaptation of a mutation rate. Additionally, cancerous cells and tumors are other examples of high mutation rates. Low mutation rates would be seen in an environment that is more stable than one a cancerous tumor is in. The low mutation rate can be favorable when change isn’t needed to survive. To me, this means low mutation rates occur when whatever is in place right now is “perfect” or near it. It is working and therefore there are minimal external pressures for change. There are different pressures and factors that can push a mutation rate to evolve to high or low. High mutation rates become adaptive when change is needed quickly and low mutation rates are evolved when change isn’t necessarily needed to survive.