| Term | Definition |
| Population | consists of all the individuals of a space that live together in one place at one time |
| Natural selection | process by which population change in response to their environment as individuals better adapted to the environment leave more offspring than those individuals not suited to the environmean |
| Adaptation | process of becoming adapted to an environment an anatomical structure physiological process or behavioral trait that improves an organism's likelihood of survival and reproduction |
| Isolation | is the condition in which two populations of the same species cannot breed with one another |
| Paleontologists | scientist who studies fossils |
| Vestigial structure | structure reduce in size and function considered to be evidence of an organism's evolutionary past |
| Homologous structures | are structures that share a common ancestry |
| gradualism | model of evolution in which gradual change over a long period of time leads to species formation |
| Punctuated equilibrium | model of evolution in which short periods of rapid change in species are separated by long periods of little or no change |
| Industrial melanism | darkening of populations of organisms over time in response to industrial pollution |
| Divergence | accumulation of difference between groups can lead to the formation of new species |
| Speciation | process by which new species are formed |
| Ecological races | population of a species the differs genetically because of adaptations to different living conditions |
| Reproductive isolation | is the inability of formerly interbreeding groups to mate or produce fertile offsprings |