In biology class, we are learning about evolution, with a special focus on natural selection. We watched a series of videos that looked at various scientific studies done on natural selection, and we got to choose the study that we think best showcased natural selection in effect. I chose a study done on variation of color in rock pocket mice populations in New Mexico. You can click here for a link to the HHMI BioInteractive page on this study. (It's pretty darn cool, I would check it out if you have time.)
In New Mexico, there are lava flows that dot the landscape, a result of a series of volcanic explosions. Rock pocket mice, that are native in New Mexico, typically live in and around a sandy, desert environment. They are normally a tan color and blend in with the sand, letting them hide from their predators that rely mainly on their sight. However, rock pocket mice that live on the lava rocks have darker fur than the mice that live on sand. Studies were done on different rock pocket mice populations that lived on lava flows to determine if the rock pocket mice were adapting to their environment, or in other words, if natural selection was in effect. To determine that a process is natural selection, four things need to be demonstrated in a population; that there has been a change over time in the amount of individuals with a certain trait in a population, that there are variations of the trait in a population, that the trait is heritable (or able to be passed on from parents to offspring), and that the trait gives a survival or reproductive advantage to individuals with it. For rock pocket mice, there has been a change in the frequency of a dark furred trait, as rock pocket mice populations that live elsewhere are mainly, if not entirely, tan colored. There is variation in the mice populations, as there are both tan and dark colored mice. The dark fur traits are heritable, as researchers found the specific gene that causes dark fur to occur and dark furred mice had dark furred offspring. On a brief tangent about that, it was found that mice from different lava flows had different genes that made their fur darker. That means that the dark fur trait was developed separately and from different genes at different lava flows, which I thought was REALLY COOL. Lastly, having dark fur on the dark lava flows helps rock pocket mice blend into the rock, which lets them avoid predators better than tan furred mice can. This gives the dark furred mice a survival advantage over the tan furred mice on the lava flows. Natural selection of darker fur traits is occuring in rock pocket mice populations across New Mexico, as having dark fur gives the mice an advantage on lava flows and, thus, a greater chance of passing on their genes. Natural selection over time made rock pocket mice more fit to their unique and changing environment.