| A | B |
|---|
| variations | any difference between individuals of the same species |
| branching tree | diagram that shows how scientists think different groups of organisms are related |
| extinct | no members of a species are still alive |
| homologous | similar structures that related species inherited from a common ancestor |
| Gradualism | the theory that evolution occurs slowly but steadily |
| Punctuated equilibria | the theory that evolution occurs during short periods of rapid change |
| fossil | preserved remains or traces of an organism that lived in the past (can be formed from bone, tooth, shell, or other part of an organism) |
| species | group of similar organisms that can mate with each other and produce fertile offspring |
| adaptation | a trait that helps an organism survive and reproduce |
| evolution | species gradually change over many generations and adapt to new conditions |
| Natural Selection | process by which individuals that are better adapted to their environment are more likely to survive and reproduce than other members of the same species |
| Scientific Theory | well-tested concept that explains a wide range of observations |
| Charles Darwin | biologist, naturalist; came up with the theories of evolution and natural selection |
