| A | B |
|---|
| population | Consists of all the individuals of a species that live together in one place at a given time. |
| natural selection | Process by which populations change in response to their environment as individuals better adapted to the environment have a better chance of reproducing. |
| 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 | Condition in which two populations of a species are separated so that they cannot interbreed. |
| extinct | Term used to indicate species that have disappeared permanently. |
| paleontologist | A scientist who studies fossils. |
| vestigial structure | Structure reduced in size and function; considered to be evidence of an organism's evolutionary past. |
| homologous structure | Structures that share a common ancestry. |
| gradualism | A model of evolution in which gradual change over a long period of time leads to species formation. |
| punctuated equilibrium | A 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 | An accumulation of differences between groups; can lead to the formation of new species. |
| speciation | A process by which new species are formed. |
| ecological race | A populaltion of a species that differs genetically because of adaptations to different living conditions. |
| reproductive isolation | Prevention of mating between formerly interbreeding groups, or the inability of these groups to produce fertile offspring. |
