Microevolution: Changes in Populations

For this post, we are going to use two different sources to research microevolution, and then answer some questions about the materials explored.

For the first part, we are going to explore Berkeley's information here. According to Berkeley, microevolution is evolution on a small scale, within a single population. They also define a population as a group of organisms that interbreed with each other and share a gene pool. There are four different mechanisms for evolution:

Mutation
Certain genes randomly mutate to another variation of gene, presenting a completely different trait than its predecessor.

Migration
Organisms from different populations will reproduce, integrating their gene pools.

Genetic Drift
When organisms reproduce, recessive genes randomly become dominant in the offspring.

Natural Selection
Organisms of one type of dominate trait will reproduce with dissimilar organisms more often than with organisms that bear their own traits, and these traits eventually die out.

There are many examples of microevolution, however, we are only going to look at three of them. The first example is the size of the house sparrow. Since 1852, the size of the American house sparrow has become longer, most likely as a cause of natural selection as the sparrows have had to adapt to the decreasing temperatures of their environment. Another example is how enterococci bacteria have become resistant to some antibiotics. Many other organisms have also built up a resistance to herbicides and pesticides. For the last example, we are going to look at how organisms have coped with global warming. While many organisms stay dormant during the winter, halting reproduction and growth, longer summers allow them to take advantage of the temperatures and accomplish what cold temperatures don't allow them to. This does, however, require evolutionary change.

For the second part of this post, we are going to use this resource.

After viewing the simulation, there are a couple of questions raised that can be connected to the larger question: Why are some guppies brightly colored, even though it makes them more visible to predators? These questions can reasonably include: Why do some guppies tend to be more colorful or drab? What role does color play in survival? What is the push and pull that the environment has on the correlation of guppies in Endler's pools?

As we can see from the simulation, when a predator is present in the guppies' environment, they blend into their surroundings, similar to how a chameleon will change color or a moth will have certain patterns on their wings. It is a mechanism of survival; if they can't be seen, they won't be hunted and will therefore survive. However, when a predator is not present, bright coloring appears in the guppies. This is because brighter coloring will attract mates, which will lead to a larger population of guppies. The larger the population, the higher probability of species survival. This situation is similar to the bright coloring in male peacocks and ducks.  As you can see, there is a strong push/pull factor when it comes to survival in an environment, and a balance must be reached to obtain a proper morality rate for species survival.

I hope that you now have a better understanding of microevolution and how it plays into the survival of a species; I know I do!