Chapter 23- Microevolution and population genetics

Microevolution

Change in allele frequencies in a population over generations.

Natural Selection

The mechanism causing adaptive evolution and improving the match between organisms and their environment.

Directional Selection

A selective mechanism that favors individuals at one end of a phenotypic range.

Disruptive Selection

A selective mechanism that favors individuals at both extremes of a phenotypic range.

Stabilizing Selection

A selective mechanism that favors intermediate phenotypes and acts against extreme phenotypes.

Genetic Drift

Chance events that alter survival and reproduction, changing allele frequencies and often reducing genetic variation.

Founder Effect

When a few individuals become isolated from a larger population, leading to a new population whose allele frequencies do not reflect those of the original population.

Bottleneck Effect

A significant reduction in population size that results in a gene pool that no longer reflects the original population's gene pool.

Gene Flow

The transfer of alleles into or out of a population, which can increase or decrease the fitness of a population.

Population

A group of individuals of the same species that live in the same area and interbreed.

Gene Pool

The total collection of alleles in a population at any one time.

Hardy-Weinberg Principle

A principle that describes how allele frequencies remain constant in a population not evolving.

Hardy-Weinberg Equilibrium Conditions

No mutations, random mating, no natural selection, very large population size, and no gene flow.