Evolution and Natural Selection

These flashcards cover key vocabulary terms and concepts from the lecture on evolution and natural selection.

Evolution

Change in allele frequency of a population over time.

Natural Selection

Process by which populations evolve; individuals with certain traits survive better and reproduce more because of those traits.

Sympatric Speciation

Gene flow is interrupted in populations that live in the same geographic area.

Allopatric Speciation

Gene flow is interrupted when a population is divided geographically.

Speciation

Process in which one species splits into two or more species.

Fossils

Remains of organisms from the past.

Charles Darwin

Developed a theory of evolution by natural selection.

Adaptations

Inherited characteristic that enhances the survival and reproduction of an organism in a specific environment.

Artificial selection

Human modification of other species over generations by selecting traits to breed.

Homology

Similarity resulting from common ancestry.

Vestigial Structures

A feature of an organism that has no use, but had a function in that organism’s ancestor.

Convergent Evolution

Evolution of similar features in independent lineages.

Postzygotic Barriers

Factors that contribute to reproductive isolation after the hybrid zygote is formed.

Phylogenetic Tree

Branching diagram that shows the evolutionary history of a group of organisms.

Monophyletic

Consists of an ancestral species and all of its descendants.

Paraphyletic

Consists of an ancestral species and some, but not all, of its descendants.

Polyphyletic

Consists of distantly related species but does not include their most recent common ancestor.

Outgroup

Closely related species that diverged early in evolutionary time; closely related, but not as closely as organisms being studied.

Genetic Variation

Differences among individuals in the composition of their DNA.

Population

Group of individuals of the same species that live in the same area.

Species

A group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring.

Gene Pool

All copies of possible alleles of a population.

Hardy-Weinberg Equilibrium

The state of a population that is not evolving.

Genetic Drift

A process in which chance events cause evolution in a population.

Founder Effect

A few individuals become isolated from a population and form a new population with a different combination of alleles.

Bottleneck Effect

Genetic drift that occurs when the size of a population is dramatically reduced.

Gene Flow

Movement of alleles into or out of the population by immigration or emigration.

Directional Selection

Conditions favor individuals exhibiting one extreme of a phenotypic range.

Disruptive Selection

Conditions favor individuals at both extremes of a phenotypic range.

Stabilizing Selection

Conditions act against both extreme phenotypes and favor intermediate variants.

Heterozygote Advantage

Individuals with a heterozygote genotype have higher fitness than either homozygous genotype.

Sexual Selection

Process in which individuals with certain inherited characteristics are more likely to obtain mates.

Reproductive Isolation

Existence of barriers that impede members of two species from interbreeding and producing fertile, viable offspring.

Hybrids

Offspring that result from an inter-species mating.

Prezygotic Barriers

Block fertilization from occurring.