Chapter 20: Genetic Variation and Evolution

Vocabulary flashcards for key terms and concepts related to genetic variation and evolution as discussed in the lecture.

Genetic Variation

Differences in alleles of genes found within individuals in a population.

Evolution

Genetic changes through time.

Hardy-Weinberg Principle

Predicts genotype frequencies under certain conditions in a population.

Hardy-Weinberg Equilibrium

Proportions of genotypes do not change in a population as long as specific assumptions are met.

Allele Frequency

The relative frequency of an allele at a genetic locus in a population.

Genetic Drift

Random fluctuation in allele frequencies in small populations.

Founder Effect

Loss of genetic variation when a small number of individuals establish a new population.

Bottleneck Effect

Drastic reduction in population size leading to loss of genetic variability.

Natural Selection

A process where individuals with advantageous traits reproduce more successfully.

Fitness

Relative measure of the reproductive success of an individual.

Parental Investment

The time and energy spent by parents in the production and care of offspring.

Intrasexual Selection

Competition among individuals of one sex for mates of the opposite sex.

Intersexual Selection

Mate choice where individuals of one sex (usually females) choose mates based on certain traits.

Sensory Exploitation

Evolution of male signals that exploit preexisting preferences in females.

Negative Frequency-Dependent Selection

Rare phenotypes are favored by natural selection.

Heterozygote Advantage

Heterozygotes have a higher fitness than homozygotes, maintaining both alleles in the population.

Disruptive Selection

Selection that favors extreme phenotypes over intermediate phenotypes.

Directional Selection

Selection that favors one extreme phenotype over others.

Stabilizing Selection

Selection that favors intermediate variants by acting against extreme phenotypes.

Mutation

A change in a DNA sequence, serving as the ultimate source of genetic variation.

Gene Flow

Movement of alleles between populations due to migration.

Nonrandom Mating

Mating between individuals based on phenotype or genotype, influencing allele frequencies.

Selection History

The evolutionary processes that shape the traits and genetic makeup of populations.