Ashley's Evolution Blog

 When I first defined evolution, I felt like I already had a pretty good understanding of how genes, natural selection, and mutations play into it. I would probably add on to this definition by including more about allele frequency and the evolutionary influences defined in the Hardy-Weinberg Principle. Additionally, I would mention how evolution can happen between generations, not just over millions of years. I have learned a lot about coding in R. I have never been at good at working technology and especially not when I have to code, which is something I have never done before this class. I enjoy being able to actually understand a few graphs, instead of just looking at a ton. It is also helping me to learn things in a way I have not ever done before. I am still struggling with Hardy-Weinberg and allele frequencies because of the math involved and plugging this into R. I want to learn more about how the topics we have learned so far have affected humans throughout the years. I wo...

I think that mutation rates evolve within the species. As a species advances and develops, many mutations will be more harmful than helpful to the individual. In the context of Darwin's 5 postulates, mutations would increase individual variation which would lead to differential survival. If one mutations helped an individual, then it would be able to survive and reproduce better than those without the mutation. For the most part, mutations will increase or decrease fitness and would lead to differences in generations on an individual level. Helpful mutations will be passed on at a higher rate than those that are detrimental to the organism's health. Additionally, smaller organisms with a higher reproductive rate will likely show a higher mutation rate in the same period time than that of a larger organism. Reproducing will lead to more mutations within the species, and an example of this is what is seen in bacteria. In humans, a low mutation rate might be more adaptive than it ...

     Natural selection is related to the phenotypes of an individual and how these traits affect their fitness. In theory, a phenotype that increases fitness will be passed on and become more prevalent in the population, yet there may be more to the genotype. Many phenotypes are influenced by more than one gene and there may be other factors that play into it, such as heterozygote advantage. Genes can be advantageous in some ways, yet lethal if they were combined with others. Natural selection may not always lead to evolutionary change because there are many factors that go into which phenotypes that are expressed. A phenotype may be advantageous to have, but it could be very difficult to track through the genotype.      One way selection could happen without natural selection if there was a natural disaster, such as a drought, flood, hurricane, etc. A population can be almost all the way wiped out during a hurricane, except for a few individuals that may h...

I define fitness as how well an organism is adapted to its environment in order to be able to survive and reproduce. If an organism is "more fit" than another, this means that it has a higher likelihood to survive and reproduce, and its offspring will do the same. This organism that has high fitness has genotypes/phenotypes that are selected for within their environment. This means that the individual does not necessarily have to be the biggest, fastest, etc. but it has traits that allow it to successfully live long enough to reproduce and have its traits passed on to the next generation. A classic example of this is brown vs green beetles fitness. If a species of beetles has both green and brown beetles living in it, yet they live in a wooded and dark area, the brown beetles would have a higher level of fitness. More of the green beetles would stand out against a dark background and would likely be preyed upon more than the brown beetles who are camouflaged within the trees....

Lamarck's view of evolutionary change through use and disuse is different from our current understanding in multiple ways. One thing this theory suggests is that the organs, structures, and traits that we do not use or benefit from would go away, but this has not happened. Humans still have vestigial structures that are pretty much useless for us to be able to function. A few examples of these vestigial structures are the appendix, wisdom teeth, as well as tails (in embryo development). These are all useless to have, and if Lamarck's theory of use and disuse were correct, then these structures would have been weeded out a long time ago. It would make sense that these useless traits would disappear over time since they seem to be a waste of energy and resources in our body, yet they still exist. These components have repeatedly shown up for hundreds of thousands of years and were likely important to some of our early ancestors. This lack of understanding of DNA and heritability ...

 My favorite prediction Darwin's idea of descent with modification makes is that species are not independent, but are connected by descent from common ancestors. I think that this is one of the most important and fundamental principles of the theory of evolution. This concept can connect all living organisms to each other and be used to analyze how evolution has occurred and where species separated. One thing I find most interesting about life is DNA and how every living thing uses DNA and/or mRNA to survive and function. The genetic code is very complex, yet works about the same in all organisms. The central dogma of biology occurs in a similar fashion in about every organism - DNA to RNA to protein. While this is very basic, I believe it says a lot about how species are connected. Sharing DNA with other organisms can explain homologous features, and how the changing of code can lead to the changing of physical features which eventually leads to speciation.  Overall, this con...