BIOL 120: Chapter 23 Activity Review

These flashcards cover key concepts related to genetic variation mechanisms as described in the lecture notes.

Disruptive Selection

Favors both extreme phenotypes, decreasing genetic variation.

Founder Effect

Reduced genetic variation when a small number of individuals establish a new population (e.g., retinitis pigmentosa on Tristan de Cunha).

Heterozygote Advantage

Maintains genetic variation because heterozygotes have greater fitness.

Intrasexual Selection

Decreases genetic variation as individuals of one sex compete for mating opportunities.

Migration

Immigration increases genetic variation, while emigration decreases it.

Stabilizing Selection

Decreases genetic variation by selecting against extreme phenotypes.

Balancing Selection

Maintains genetic variation through frequency-dependent selection and heterozygote advantage.

Directional Selection

Decreases genetic variation by favoring one extreme phenotype, shifting the trait average.

Bottleneck Effect

Reduced genetic variation due to a severe drop in population size.

Intersexual Selection

Decreases genetic variation; one sex (often females) typically chooses mates based on specific traits.

Natural Selection

Decreases genetic variation by favoring advantageous phenotypes influenced by environmental pressures.

Mutation

Increases genetic variation through new alleles created by genetic errors.