Evolution is descent with modification. It is the study of how complex living organisms have descended from earlier less complex ancestors in the history of Earth. Probably the first and most important mechanism of evolution is natural selection, which was proposed by Charles Darwin when he wrote” The Origin of Species.” After Darwin’s theory of evolution was modified by the modern synthesis theory, other mechanisms of evolutionary change were discovered. These mechanisms became known as mutations, genetic drift, and gene flow. Mutations are responsible for creating certain variations in gene pools which contributes to the heritable differences in a population. Mutations are changes in the nucleotide sequences of DNA. They are the primary source of genetic variation, and can have beneficial and harmful effects. Point mutations are considered harmless while chromosomal mutations that rearrange or delete …show more content…
Migrating individuals go to interbreed with a new population and contribute a significant amount of their genes to that gene pool. As a result, the similarity of the migrating individuals’ population and the population they interbred with increases because of gene flow. The most important mechanism of evolutionary change is natural selection. The better adapted individuals are more likely to pass on their genes more efficiently than the less fit individuals. Over time, the offspring become better adapted to their environment. There are three types of natural selection that act on populations. Directional selection favors an extreme phenotype over an intermediate individual and also against another extreme phenotype. Stabilizing selection favors the average individuals or intermediate phenotypes over all the extreme phenotypes. The last type of natural selection is disruptive selection, which favors only individuals with extreme phenotypes over the average