Evolution and Natural Selection

adaptation

An inherited trait that improves an individual's ability to survive and reproduce in a particular environment.

artificial selection

Selective breeding of plants and animals to promote the occurrence of desirable traits in offspring

evolution

Change in allele frequency of a population over time. Can lead to speciation

fossil record

A term used by paleontologists to refer to the total number of fossils that have been discovered, as well as to the information derived from them

gene pool

All of the alleles in all the individuals that make up a population

homologous structures

Structures in different species that are similar because of common ancestry.

factors of natural selection

1. genetic variation

2. environmental challenges

3. competition 4. "survival of the fittest"

reproductive isolation

Condition in which a reproductive barrier (physical or behavioral) keeps two species from interbreeding

speciation

A process typically caused by the genetic isolation from a main population resulting in a new genetically distinct species.

geographic isolation

form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water

vestigial structures

A structure that is present in an organism but no longer serves its original purpose

punctuated equilibrium

Pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change

gradualism

Pattern of evolution in which change in a species occurs slowly.