Mechanisms of Evolutionary Change (Study)

Natural Selection

A mechanism of evolution where organisms better adapted to their environment tend to survive and produce more offspring.

Stabilizing Selection

A type of natural selection that favors average phenotypes and selects against extremes.

Directional Selection

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

Disruptive Selection

A type of natural selection that favors both extreme phenotypes and selects against the average phenotype.

Fluctuating Selection

Selection that varies over time, favoring different traits depending on changing environmental conditions.

Founder Effect

A phenomenon where a small group from a larger population starts a new population, leading to reduced genetic diversity.

Genetic Drift

A random change in allele frequencies in a population, often having a larger impact in small populations.

Allele Frequency

The relative frequency of an allele at a genetic locus in a population, expressed as a proportion.

Gene Flow

The transfer of genetic variation from one population to another due to migration.

Adaptation

A characteristic that enhances the survival and reproduction of organisms in a particular environment.

Biological Species Concept

Defines a species as a group of individuals that can interbreed in nature and produce viable offspring.

Sympatric Speciation

Speciation that occurs when populations are in the same geographic area but become reproductively isolated.

Allopatric Speciation

Speciation that occurs when populations are geographically isolated from each other.

Prezygotic Isolation

Mechanisms that prevent mating or fertilization between species.

Postzygotic Isolation

Mechanisms that occur after fertilization, preventing the hybrid offspring from developing into a viable adult.

Species

A group of organisms capable of interbreeding and producing fertile offspring.

Hybridization

The process of combining different varieties of organisms to create a hybrid.

Ecosystem

A biological community of interacting organisms and their physical environment.

Carrying Capacity

The maximum population size that an environment can sustain indefinitely.

Biogeography

The study of the distribution of species and ecosystems in geographic space and through geological time.

Phylogenetics

The study of evolutionary relationships among biological entities, often species.

Extinction

The permanent loss of all members of a species.

Mutualism

An interaction between species that is beneficial to both.

Commensalism

An interaction where one species benefits and the other is neither helped nor harmed.

Parasitism

An interaction where one organism benefits at the expense of another.

Invasive Species

Non-native species that spread widely and cause harm to native species and ecosystems.

Conservation Biology

The scientific field focused on the preservation of biodiversity.

Limiting Factor

An environmental factor that restricts population growth.

Succession

The process by which ecosystems change and develop over time.

Carbohydrates

Organic compounds consisting of carbon, hydrogen, and oxygen, often serving as a major energy source.