| Term | Definition |
| population | all of the individuals of a species that live together in one place at one time. |
| isolation | the condition in which two populations of the same species cannot breed with one another |
| extinct | permanently gone. The dinosaurs are extinct. |
| paleontologist | a scientist who studies fossils |
| mutation | change in genes or chromosomes that causes a new trait to be inherited |
| vestigal structure | a part of an animal's body that has no use or less of a use than in the past |
| homologuous structure | structures that share a common ancestry |
| gradualism | gradual change over time leads to species formation |
| industrial melanism | the darkening of a population due to industrial pollution |
| ecological race | populations of a species that differ due to adaptations to different living conditions |
| reproductive isolation | inability of formerly interbreeding groups to mate or produce fertile offspring |
| Lamark | He had an incorrect theroy about how animals passed on traits |
| Darwin | the "father" of modern evolution theroy |