Unit 2: Evolution Vocabulary

Artificial selection

Darwin's term for the selective breeding of organisms selected for certain traits in order to produce offspring having those traits

Natural selection

theory of evolution developed by Darwin, based on four ideas: excess reproduction, variations, inheritance, and the advantages of specific traits in an environment

Evolution

hereditary changes in groups of living organisms over time

Fitness

measure of a trait's relative contribution to the following generation

Genetic drift

random change in allelic frequencies in a population

Founder effect

random effect that can occur when a small population settles in an area separated from the rest of the population and interbreeds, producing unique allelic variations

Bottleneck effect

process in which a large population declines in number, then rebounds

Stabilizing selection

most common form of natural selection in which organisms with extreme expressions of a trait are removed

Directional selection

shift of a population toward an extreme version of a beneficial trait

Disruptive selection

process in which individuals with average traits are removed, creating two populations with extreme traits

Adaptive radiation

diversification of a species into a number of different species, often over a relatively short time span

Adaptation

inherited characteristic that increases an organism's chance of survival

gene flow

Movement of alleles into or out of a population due to the migration of individuals to or from the population

behavioral isolation

isolation between populations due to differences in courtship or mating behavior

convergent evolution

Process by which unrelated organisms independently evolve similarities when adapting to similar environments

geographic isolation

isolation between populations due to physical barriers

Mutation

change in a DNA sequence that affects genetic information

Speciation

the formation of new and distinct species

Coevolution

process in which two or more species evolve in response to changes in each other

Trait

A characteristic that an organism can pass on to its offspring through its genes.

Gene

a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring.

sexual selection

when individuals select mates based on heritable traits

gene pool

Combined genetic information of all the members of a particular population

Migration

movement from one place to another

reproductive isolation

Separation of species or populations so that they cannot interbreed and produce fertile offspring

temporal isolation

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

Species

A group of organisms that are closely related and can mate to produce fertile offspring

gene frequency

how often a particular gene occurs in the population