Unit Two: Natural Selection, Allele Frequency, Speciation, and Extinction

These flashcards cover key concepts of natural selection, allele frequency, speciation, and extinction from the lecture notes.

Allele

Different forms of a gene.

Allele Frequency

How common each allele is in a population.

Natural Selection

A non-random process where traits that help survival and reproduction become more common in a population.

Directional Selection

A pattern of natural selection where an extreme trait is favored and the population shifts toward that extreme.

Stabilizing Selection

A selection pattern that favors the average form of a trait, decreasing variation by selecting against both extremes.

Disruptive Selection

A selection pattern that favors both extreme traits while selecting against the average form, potentially splitting the population into two groups.

Speciation

The process by which populations become reproductively isolated and evolve into distinct species.

Geographic Barriers

Physical barriers that prevent populations from interbreeding, leading to speciation.

Background Extinction

A slow, natural ongoing extinction rate throughout Earth's history.

Mass Extinction

A rapid loss of many species at once caused by major global events.

Minimum Viable Population (MVP)

The smallest population size needed for a species to survive long term.