Amy Schaulis - Evolutional Thoughts

Over the course of this semester we have examined the various forces that drive evolution. Selection is one such force, describing the increased likelihood of survival and reproduction in certain species that exists due to variances in genetic characteristics within a population. These genetic characteristics might serve to make an organism more desirable for mating and reproduction purposes, or better suited to the environment, making it more adept at competing for resources. Given that this process curtails members of a population less fit to survive while encouraging the reproduction of members with a higher fitness level, one would think that selection would lead to the elimination of genetic variation over time. Yet, this theory does not translate into the real world as we don’t observe populations losing their genetic variation, even when highly advantageous mutations exist within a population and make it especially fit to thrive within its environment. There are two reasons for ...

Can you describe how Kimura's theory of neutral evolution is different from the theory of evolution by natural selection? How are they the same? The theory of evolution by natural selection is based around the main concept of survival of the fittest. As species mutate, the traits that are found to be more advantageous with higher fitness become more selected, allowing those who possess these traits to survive, reproduce, and pass them on to further generations for better survival rates. These traits become fixated in the population. Those who have traits that are less desirable and deleterious will die off, eventually phasing out of the population's gene pool. On the other hand, Kimura's theory of neutral evolution claims that the fixation of alleles and mutations is mainly due to the concept of genetic drift. In this theory, Kimura infers that allele fixation is more random than predictable, attempting to refute the central idea behind natural selection. In fact, Kimura be...

Inbreeding is a common phenomenon in nature, with countless populations using this as a method of reproduction as opposed to random mates. A major benefit of inbreeding is that it enables you to be more selective with certain traits, providing you with a smaller gene pool to select from. A major example of this can be seen in domesticated dog breeds. Although not natural, the ability to control inbreeding in dogs enables us to create specific breeds. By breeding two related dogs, it is almost guaranteed that the genetic diversity will be kept at a minimum, assuring the offspring has the desired traits. Also, it helps insure that a new dog will be a purebred rather than a mix with another breed. Assortative mating evolves to become more common as the gene pool decreases, causing an increase in preference to mates with similar phenotypes.  While inbreeding poses the benefit stated above, it has more than its fair share of disadvantages that encourage avoidance of assortative mating. ...

When it comes to water snakes of Lake Erie, there are four major phenotypes to look at. Types A, B, and C live on the island, with  type A being a stripe-less gray color and types B and C having a reduced number of stripes. Type D lives on the mainland, with it having a significantly higher number of stripes than those found on the island. Due to these trends, the percent of each phenotype found in the populations can be very informative as to the environment as well as the location.  In Ontario, the mainland, the population consists of nearly 100% type D, where the high frequency of stripes assists in disguising the snakes in the leaf-ridden forest streams, working as camouflage as a survival mechanism adapted to the environment. While the peninsula is still a far majority of type D due to being attached to the mainland, you begin to see a slight mixture of the other phenotypes, likely due to migration from island to mainland. Kelleys Island and the Bass complex isl...