Blog Post Module 7
Not going to lie, before beginning this course, I thought I had it all figured out. I thought I knew everything I needed to know about evolution because I had taken similar courses before and studied for the MCAT all summer. Boy, was I wrong! There are many other aspects to evolution than I originally thought. I have at least heard about the subjects that have been taught in this course so far, but I have never learned about them so in-depth and with specific examples. The "cave mollies" R exercise was very interesting because one could see the effects of inbreeding in the population as a result of the limited carrying capacity. I also learned more about inbreeding and that sometimes breeding individuals with similar traits can actually be beneficial for a population. This process is called assortative mating.
In my first blog post, I said that evolution is like the fluid mosaic model of the cell membrane, meaning that organisms are constantly changing due to environmental conditions. Now, I would say that is still pretty accurate. The traits that show up in a population are a result of changes that occur over generations and accumulate over time as a result of changing environmental conditions. While this definition can be accurate, however, there are many other aspects that play a role in evolution, such as mutation rate, migration into or out of the population, genetic drift, and nonrandom mating. I would definitely say that my definition from the beginning of the semester until now has not changed as a whole because the central message is still there, but has "evolved" into something more specific and detailed.
Something I am still confused about it is how DNA mutations actually come about. What are some factors that cause these mutations? Why don't DNA repair mechanisms just repair them right away? In addition, I have had some trouble with genetic drift, such as a specific example of genetic that we have seen in nature.
Lastly, something I want to learn about is a bottleneck. I have heard the term thrown around here and there but I do not actually have a good understanding of it. Even when I google it, it is still a bit confusing because I couldn't find any good examples of this happening in a population. Also, I want to learn more about how pollution to different habitats from humans has caused animals to evolve, such as the example I mentioned in module 5 with DDT and frogs.
Hi Casey!
ReplyDeleteFirst, I hope your MCAT studying went well this summer! Secondly, I completely agree with your analogy that evolution is similar to a fluid mosaic model! Finally, in regard to why DNA repair mechanisms don't just fix the mutations right away it has to do with a mutation with the DNA polymerase. DNA polymerase are the enzymes responsible for the proofreading and assembling new DNA strands from one DNA molecule. Its common that a mistake is made for about one in every billion base pairs copied. When these mistakes or mutations come about, deficient DNA polymerase is unable to correct the misplaced base pairs and causes portions of DNA strand to be misread and in turn causes mutations!
Hi Casey,
ReplyDeleteInteresting reflection you have here! I would have to agree about the way that my conceptualization of evolution has changed over the last few weeks of this class. Especially with, like, genetic drift and mutation rate and how those can more or less "counteract" selection, which is certainly not something that I think we're taught much prior to a class like this. It's odd to think about how evolution makes us into the adapted creatures that we are but, on the other side of that coin, it also makes us the limited creatures that we are. Thanks for sharing!
Casey,
ReplyDeleteI related a lot when you said coming into this class you thought you knew it all. I also was studying for the MCAT, and the prep material made it seem like once you knew Darwin's 5 postulates than you essentially knew everything about evolution, but clearly this class has shown us that there is so much more to it. I also am still confused about some of the genetic mutations and how they are always popping up, so I hope that we are able to cover that more in this class. Your point about bottleneck and pollution is interesting and those are things that I think would be really cool to learn about in here!
Hi Casey! I really like your comparison of evolution to the fluid-mosaic model of the cell-membrane. I think that is a very good insight! Also, it confuses me as well how a DNA repair-mechanisms randomly fail in the case of mutations. Studying human health biology and biology in general has ingrained in me an appreciation for the sheer intelligence that living things have on a molecular level and I find it strange that a mutation just randomly slips by every now and then.
ReplyDeleteHi Casey,
ReplyDeleteI agree with you as we are passing days in this class our perception of evolution is constantly changing. I am also confused about how DNA mutations actually come about. What are some factors that cause these mutations?