Natural Selection and Gene Flow

1. Natural Selection and Gene Flow Allie & Alena

2. Natural Selection • Individuals in a population have different characteristics based on their heritable traits • Those with the most favorable traits survive more frequently to pass on these traits to their offspring

3. Natural Selection • Selection results in alleles being passed to the next generation in proportions different than the present generation. • Ex: Drosophila Melanogaster has an allele that makes it resistant to some insecticides. As time goes on, this allele has become more common in populations exposed to insecticides.

4. Natural Selection • By consistently favoring some alleles over others, natural selection can cause adaptive evolution (evolution that results in a better match between organisms and their environment).

5. Gene Flow • The transfer of alleles in or out of a population due to the movement of fertile individuals or their gametes. • Gene flow tends to reduce genetic differences between populations. • If it’s extensive enough, it can result in neighboring populations combining into one.

6. Gene Flow and Human Evolution • The migration of people throughout the world has increased and this has increased gene flow between populations that were once isolated from one another.

7. Gene Flow and Human Evolution The computer generated image on this magazine cover illustrates how gene flow can homogenize the gene pools of populations, thereby reducing geographic variation in appearance.