Microevolution

Microevolution

Change in allele (gene) frequencies in a population across generations.

Allele frequency

The proportion of a particular allele among all allele copies in a population.

Natural selection

Process by which individuals with traits that increase survival and reproduction leave more offspring.

Stabilizing selection

Favors average phenotypes and reduces extremes.

Directional selection

Favors one extreme phenotype.

Disruptive selection

Favors both extreme phenotypes and eliminates average phenotypes.

Nonrandom mating

A form of mating where mate choice is selective, affecting genotype frequencies in a population.

Mutation

Change in DNA sequence; the only source of new alleles.

Genetic drift

Change in allele frequencies due to chance events, particularly impactful in small populations.

Bottleneck effect

A drastic reduction in population size due to a random event, leading to a loss of genetic diversity.

Founder effect

When a small group colonizes a new area, resulting in a population that reflects the founders' genes.

Migration (Gene Flow)

The movement of individuals between populations, introducing new alleles and increasing genetic variation.

Hardy–Weinberg Principle

Describes conditions under which a population does not evolve; includes no natural selection, random mating, no mutation, large population size, and no migration.

Kauai crickets

An example of microevolution where male crickets evolved noiseless wings due to predation over approximately 20 generations.