Blog Post Module 3

Fitness in general is something our population does not understand very well, because even in humans, all people assume that being more "physically fit" is what would constitute having the highest fitness in a population. One phrase that often goes along with this topic is the age-old phrase "survival of the fittest", which is usually an attempt compile theories of evolution into one small and not very helpful phrase. After having studied evolution, both in this class and in other biology classes, I realize that "survival of the fittest" doesn't mean that the bodybuilders are going to be the last ones left on earth if some disease, disaster, or predator comes in to wipe all of the "less fit" people out of existence. It means that organisms who are most fit for their environment have the upper hand in survival and ultimately reproduction.

I would define fitness as an organism's ability to survive and reproduce successfully in their given environment. Fitness in terms of evolution is not at all comparable to how we usually use the word "fitness" to mean muscular, strong, or healthy. An individual could be extremely large and muscular, but not be the most fit to their environment because they don't fit in habitats or are easily spotted by predators, for example.  It could also have nothing to do with physical appearance at all! One example may be that a species that lives in a dessert environment normally needs to drink 3-5 mls of water per week, but there is a genetic mutation that allows some of these animals to leave solely off of their metabolic body water and they never actually have to drink water. This mutation would make the animal more fit to their environment because in the even that water could not be found, they would stand a much better chance at reproduction and survival than their non mutated peers. 

One example I can think of that takes me back to something I learned in one of my first biology classes ever is the color differences of Rock Pocket Mice. These mice come in both dark and light color, but depending on their environment, the frequency of the colors present can vary drastically. The first step in trying to determine the different fitness of the mice in these environments would be to determine the possible different environments and different colors of mice. In this case, there are really only two of each that are ever mentioned--light and dark mice, and light sandy areas or dark lava rock areas. Then, I would find a population that had some mice of both colors in their population (or if this didn't exist, bring the lacking color of mice into the environment to observe what happens). Then, I would observe how many mice of each color were able to  reproduce before dying, and how they ultimately died. This criteria would help to show that in light sandy areas, dark mice were getting killed much earlier on in life and much more often by predators because it was very hard to conceal themselves in the light colored area around them-- the same would occur to light mice in a dark lava rock area. This would allow me to show that light colored mice are simply more fit for the sandy environments and dark mice are more fit for the lava rock environments because each of them has the advantage of survival and reproduction within these new areas.