| A | B |
|---|
| natural selection | organisms well suited to their environment survive and reproduce at a greater rate than less well-adapted organisms |
| fossil | the preserved remains or evidence of an ancient organism |
| homologous | structures that have different mature forms in different organisms but develop from the same embryonic tissues |
| vestigial | structures that have reduced in size because they no longer serve an important function |
| adaptation | the process by which a species becomes better suited to its environment is known as |
| ecological races | populations of the same species that differ genetically because they have adapted to different environments |
| gradualism | the hypothesis that evolution occurs at a slow rate |
| punctuated equilibrium | the theory that evolution occurs at an irregular rate |
| Galapagos Islands | one of the locations that Darwin visited and that played a role in his theory of natural selection |
| evolution | a change in species over time |
| HMS Beagle | the name of the ship on which Charles Darwin sailed |
| artificial selection | selection by humans for breeding of useful traits from the natural variation among different organisms |
| struggle for existence | competition among members of a species for food and living space |
| living space | and the other necessities of life |
| fitness | the ability of an organism to survive and reproduce in its environment |
| adaptation | inherited characteristic that increases an organism's chance of survival |
| natural selection | process by which individuals that are better suited to their environment survive and reproduce most successfully |
| common descent | principle that all living things were derived from common ancestors |
| descent with modification | principle that each living species has descended |
| Charles Darwin | proposed the mechanism for evolution that he called natural selection |
