Blog Post Module 8

 Although selection is a major mechanism by which evolution functions, it is not even close to the only one. Selection, genetic drift, migration, mutation, non-random mating, and more play a role in creating the composition of populations. Selection may favor specific traits in organisms and then allow those to be passed on, but at any point in time the environment could shift causing those same traits to be unfavorable. And then selection will kick in once again and the allelic frequencies of that population will shift to better fit with the current circumstances. Short-term, selection might reduce genetic variation, but if you look at the big picture it really doesn't. Certain places might stay somewhat constant, but the world as a whole is constantly shifting and changing. One slight change could have major ramifications for selection and therefore the population as a whole. This isn't a one and done kind of thing. 

Additionally, as I stated before, selection is only one piece of the complex puzzle that is evolution. Mutation also plays a major role in all of this. Mutation causes changes in the genome that can introduce new alleles, new gene functions, and new traits in organisms and over time the population. This increases genetic variation and alters the pool of traits selection has to work with. A population could mostly be comprised of a genotype for a trait that seems to be most favorable for survival, but if a mutation is introduced that is even more beneficial, well all of a sudden things are out of wack again. Additionally, even if a deleterious allele is introduced, it can be propagated in that population by hiding out in heterozygotes where selection can't touch it. This definitely increases variation rather than reducing it.

Overall, evolution is not a linear dead end process. It is impacted by many things so it is important to be aware of how different aspects overlap to create the physical result. Don't get me wrong, it is good to know how each mechanism functions independently, but they all play on and off of one another. Just looking at selection, you might believe evolution functions to reduce biodiversity and the abundance of life around us, but in actuality that couldn't be further from the truth. Just like a recipe, you need all the ingredients to get that result, but you couldn't get there with just the flour. Everything has to come together to make it work.

Comments

  1. Casey WorleyOctober 18, 2021 at 1:57 PM

    Emily, I love your explanation of how evolutionary forces are not independent of each other, as they each play affect one another and to great extents. I may add that these R exercises we have been doing are very beneficial for examining how each evolutionary force acts indecently, as it deepens my understanding of them on an individual level.

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  2. Tatum GlaserOctober 20, 2021 at 11:02 AM

    Hi Emily! I really liked you explanation of how all the evolutionary forces work together like a recipe, great analogy! I think we saw just how quickly mutations can create variation with the COVID-19 R exercise. I used to think that selection was the main driving force of evolution but I've gotten to learn just how much goes into it!

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  3. Kaitlyn ChappelOctober 22, 2021 at 5:22 PM

    Emily, I love your explanation and opinions for this module. It is really easy to think of selection when discussing evolution but it is most certainly not the only mechanism we see or discuss in this class. Describing how evolutionary forces come together like a recipe was an awesome analogy and is one that really sticks! I would have to agree with Casey as the R exercises have been a great way to visualize how the evolutionary forces work.

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