Evolution and natural selection review
|Evolution||The process by which modern organisms have descended from ancient organisms over time|
|Common ancestor||An ancestor shared by two or more descendant species|
|Natural selection||Evolutionary mechanism in which individuals that are better suited to their environment survive and reproduce most successfully|
|Variation||Difference between traits in individuals of the same species|
|Adaptation||A trait that improves an organism's ability to survive and reproduce in an environment|
|Fitness||The ability of an organism to survive and reproduce|
|Artificial selection||Selective breeding of organisms to promote the appearance of desirable traits in offspring|
|Genetic drift||A mechanism of evolution in which allele frequencies of a population change over generations due to chance|
Darwin's theory of evolution
Common mistakes and misconceptions
- Evolution is not the same as adaptation or natural selection. Natural selection is a mechanism, or cause, of evolution. Adaptations are physical or behavioral traits that make an organism better suited to its environment.
- Heritable variation comes from random mutations. Random mutations are the initial cause of new heritable traits. For example, a rabbit can't choose to have a different fur color. Rather, a genetic mutation causes a difference in fur color, which may help that rabbit hide better in its environment.
- Natural selection acts on existing heritable variation. Natural selection needs some starting material, and that starting material is heritable variation. For natural selection to act on a feature, there must already be variation, and that variation must be able to be passed on to offspring.
- Natural selection depends on the environment. Natural selection doesn't favor traits that are somehow inherently superior. Instead, it favors traits that are beneficial in a specific environment. Traits that are helpful in one environment might actually be harmful in another.