Microevolution in Finches & Anoles (HHMI Videos) Finches: Microevolution is observed through changes in beak size and shape due to environmental press

Microevolution

Evolutionary changes at or below the species level, often observed in changes in traits such as beak size in finches due to environmental pressures.

Natural Selection

The process by which traits that provide a survival advantage become more common in a population over time.

Population

The smallest unit that can evolve; individuals do not evolve, but populations do through changes in allele frequencies.

Homologous Structures

Anatomical features in different species that share a common ancestry but may serve different functions, like whale flippers and human hands.

Vestigial Structures

Homologous structures that have lost their original function, such as the human appendix.

Biogeography

The study of the geographic distribution of species, helping to explain how species evolve differently in isolation.

Hardy-Weinberg Equilibrium

A condition under which allele frequencies in a population remain constant, requiring large population size, no mutations, no natural selection, random mating, and no gene flow.

Genetic Drift

A random change in allele frequencies within a population, often having a more significant effect in small populations.

Founder Effect

The reduced genetic diversity that results when a small number of individuals from a population start a new population.

Bottleneck Effect

A significant reduction in the size of a population, leading to a loss of genetic diversity.

Mutation

A change in an organism’s DNA that can create new alleles.

Gene Flow

The transfer of genetic material between populations, affecting allele frequencies.

Recombination

The process during sexual reproduction where alleles are shuffled, contributing to genetic variation.

Directional Selection

A type of natural selection that favors one extreme phenotype over others in a population.

p² + 2pq + q² = 1

The Hardy-Weinberg equation used to calculate allele frequencies in a population, where p is the frequency of the dominant allele and q is the frequency of the recessive allele.

Heterozygous

An individual with two different alleles for a particular gene.

Homozygous Recessive

An individual with two identical recessive alleles for a particular gene.