Natural Selection and Mice, Essay Example

Natural selection involves the adaptation of a species over a period of time.  In addition, natural selection results from a variation in genetics for a given population, with the notion that some of those species in the population will leave more offspring in the following generations.  Basically, a species may possess trait that helps the species survive and reproduce. Natural selection is also acted on through genetic variation which occurs through random mutation. Random mutation is unaffected by what an organism needs or wants in a population, but if a population exhibits a genetic variation that helps the organism survive compared others within the population, they may reproduce more and have more offspring, and the population will evolve for that genetic variation.  (Berkeley.edu) In the case with the mice, in which there were initially twenty mice, ten of which were very fast, five medium fast, and 5 very slow and cat was introduced that could catch mice apart from the very fast mice. At first, there were fewer mice; however, after some time there were more mice than in the beginning. We can hypothesize that the mice that were considered “very slow” and “medium fast” were eliminated by the cat leaving the “very fast” mice.  The “very fast” mice reproduced and the offspring inherited the “very fast” genes, in which the genetic variation was evolving.

Humans do not exhibit such vast and short changes in regard to genetic variation as other organisms.  For one, the gestation period of a human is around nine months; whereas, a mouse is about 20 days.  In addition, humans generally have only one offspring and mice can have around 10 offspring. Therefore, mice are capable of reproducing very quickly.  In the case above, the mice with the genetics for fastness were surviving and most likely passing on this particular gene to their offspring. The cat, therefore, could not catch these mouse and the numbers grew rapidly. Although humans face issues of survival and reproduction, they are able to adjust the environment with medical technology and other technologies.  Due to these modifications and lower birth rates in humans, genetic variation and natural selection is difficult to observe in the human population.

References

Berekely.edu.  Misconceptions about evolution. Understanding Evolution. Retrieved from: http://evolution.berkeley.edu/evolibrary/misconceptions_faq.php#a8