| A | B |
|---|
| evolution | change in a kind of organism over time; process by which modern organisms have descended from ancient organisms |
| theory | well-tested explanation that unifies a broad range of observations |
| fossil | preserved remains or evidence of an ancient organism |
| artificial selection | selection by humans forbreeding of useful traits from the natural variatios among different organisms |
| struggle for existance | competition among members of a species for food, living soace, and other necessities of life |
| fitness | ability of an organism to survive and reproduce in its environment |
| adaptation | inherited characteristics that increases an organism's chance of survival |
| survival of the fittest | process by which individuals that are better suited to their environment survive and reproduce most successfully; also called natural selection |
| natural selection | process by which individuals that are better suited to their environment surive and reproduce most successfully; also called survival of the fittest |
| descent with modification | principle that each living species has descended, with changes, from other species over time |
| common descent | principle that all living things have a common ancestor |
| homologous structures | structures that have different mature forms in different organisms but develop from the same embryonic tissues |
| vestigial organ | organ that serves no useful function in an organism |
