Evolution and Natural Selection

These flashcards cover key vocabulary terms related to evolution and natural selection.

Evolution

The change in the heritable characteristics of biological populations over successive generations.

Natural Selection

The process whereby organisms better adapted to their environment tend to survive and produce more offspring.

Artificial Selection

The human practice of breeding animals or plants for particular traits.

Comparative Anatomy

The study of the similarities and differences in the anatomy of different species.

Comparative Embryology

The comparison of embryos of different species to understand developmental processes.

Homologous Structure

Structures in different species that are similar because of common ancestry.

Analogous Structure

Structures in different species that serve similar functions but do not share a common ancestor.

Population

Group of individuals of the same species living in a specific area.

Gene Pool

The total collection of genes and their alleles within a population.

Microevolution

Small-scale evolutionary changes that occur within a population.

Macroevolution

Large-scale evolutionary changes that occur over long periods of time.

Hardy-Weinberg Equilibrium

A principle that describes the genetic variation in a population that remains constant from one generation to the next in the absence of disturbing factors.

Genetic Drift

Random changes in allele frequencies in a population.

Bottleneck Effect

A sharp reduction in the size of a population due to environmental events.

Founder Effect

The reduced genetic diversity that occurs when a population is established by a small number of individuals.

Gene Flow

The transfer of genetic material between populations.

Variation

Differences in traits among individuals in a population.

Heterozygote Advantage

A situation where heterozygous individuals have a higher fitness than homozygous individuals.

Fitness (evolutionary sense)

The ability of an organism to survive and reproduce in its environment.

Stabilizing Selection

Natural selection that favors average individuals in a population.

Disruptive Selection

Natural selection that favors extreme traits over average traits.

Directional Selection

Natural selection that favors one extreme phenotype over others.

Sexual Selection

A form of natural selection arising through preference by one sex for certain characteristics in individuals of the other sex.

Adaptation

A trait that increases the fitness of an organism.

Phylogeny

The evolutionary history and relationships among individuals or groups.

Reproductive Barrier

Any factor that prevents individuals from different populations from interbreeding.

Prezygotic Barrier

A reproductive barrier that occurs before fertilization.

Postzygotic Barrier

A reproductive barrier that occurs after fertilization.

Habitat Isolation

When two species live in different habitats and do not meet.

Behavioral Isolation

Differences in courtship or mating behaviors prevent species from interbreeding.

Temporal Isolation

Two species breed at different times of day, season, or years.

Mechanical Isolation

Morphological differences prevent successful mating.

Gametic Isolation

Sperm from one species may not fertilize eggs of another species.

Hybrid Inviability

Hybrid offspring do not survive or reach maturity.

Hybrid Sterility

Hybrid offspring are sterile and cannot reproduce.

Speciation

The process by which new species arise.

Allopatric Speciation

Speciation that occurs when populations are geographically isolated.

Sympatric Speciation

Speciation that occurs without geographic separation.

Polyploidy

The condition of having multiple sets of chromosomes.

Transitional Form

Fossils or organisms that show intermediate states between an ancestral form and that of its descendants.

Phylogenetic Tree

A diagram that represents evolutionary relationships.

Root (phylogenetic tree)

The common ancestor of all taxa on the tree.

Node (phylogenetic tree)

A point at which a single lineage splits into two or more lineages.

Outgroup

A taxon that diverged before the groups being studied.

Convergent Evolution

The process where organisms that are not closely related evolve similar traits.

Divergent Evolution

The process where related organisms become more dissimilar over time.