16 - definitions Evolution Unit

natural selection

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

genetic variation

Differences among individuals in the composition of their genes or traits

Fitness

an individual's ability to survive and reproduce

gene pool

Collection for all the traits in a population; contains all of the alleles

allele frequency

Percentage or fraction of an allele in a gene pool

genetic equilibrium

situation in which allele frequencies remain constant

polygenic traits

traits controlled by two or more genes which produces a range of possible phenotypes

Hardey-Weinberg Principle

States that allele frequencies in a population should remain constant unless one or more factors cause those frequencies to change.

genetic drift

Allele frequencies in a population change as a result of RANDOM events

directional selection

type of natural selection that favors ONE extreme trait

artificial selection

Selection by humans for breeding of useful traits from the natural variation among different organisms

founder effect

allele frequency changes due to the migration of a small sub group

bottleneck effect

elimination of alleles in a population due to a disaster

Coevolution

Process by which two related species evolve in response to changes in each other

stabilizing selection

type of natural selection that favors the MEDIUM trait

disruptive selection

type of natural selection that favors BOTH EXTREME traits