Microevolution

Microevolution

Gene Pool: All of the genes in a species.

Genetic Drift: The variation of different genotypes in a population. Allows gene fixation to occur.

Bottleneck Effect: When a natural (random) disaster occurs and wipes out a large portion of the population. The small amount of remaining organisms only have a small amount of the gene pool because most organisms have been eliminated. Large loss of genetic variation.

Changes in Genetic Frequency

Mutation: Mutations in the genes of an organism can cause undesirable traits to form. These organisms will add these genes to the gene pool if they reproduce. The genetic frequency of mutations goes up.

Gene Flow: Organisms move in and out of a population. Since new genes are joining and other ones are leaving, the gene frequency changes.

Non-random Mating: Organisms are bred for specific desired traits. This causes the undesirable traits to be eliminated. These traits may be helpful or harmful. The genetic frequency of chosen traits goes up.

Genetic Drift: The variation of different genotypes in a population. This causes the genetic frequency to change. Some traits become fixated and other traits disappear.

Natural Selection: Natural Selection kills the weaker members of a species. The undesirable traits that caused these organisms to disappear will eventually die out, making the population stronger as a whole.

Definitions

Reproductive Isolation

Geographic Isolation: When populations are isolated by a natural barrier.

Behavioral Isolation: Different behaviors cause the populations to be separated.

Temporal Isolation: Separation by different mating times.

Allopatric Speciation: Organisms live in different populations.

Sympatric Speciation: Organisms live in the same population.

Hybridization: When different species breed to make a hybrid.