| A | B |
|---|
| extinction | end of an evolutionary line or the end of a species, family, or of a larger group of organisms |
| fossil | physical evidence of an organism that lived long ago |
| fossil record | collection of fossils that represents the preserved history of living things on earth |
| homologous structures | structures in present in different species that demonstrate a common evolutionary origin (whale flipper and bat wing) |
| vestigial structures | structures present in modern day organisms that no longer seem to be necessary, but likely served a purpose in an ancestor (leg bone remnants in pythons) |
| species | a group of organisms that can breed with one another and produce fertile offspring in a natural environment |
| speciation | the process by which new species evolve from old ones |
| biological evolution | change in populations of living organisms on planet Earth through time |
| natural selection | the explanation for evolutionary change that states organisms with the best adaptations survive and reproduce |
| camouflage | adaptations where an organism blends with its environment |
| adaptation | any trait, behavior, physical feature, or physiological feature that helps an organism survive |
| variation | differences in genes or genetic traits within a species |
| directional selection | the extreme variation of a trait is selected for in a population |
| stabilizing selection | the average form of a trait is selected for in a population |
| disruptive selection | both extreme forms of a trait are selected for in a population |
| analogous structures | structures in different species that may look similar but do not indicate any common ancestry (bat wing and butterfly wing) |
