| Term | Definition |
|---|
| evolution | change over time; process by which modern organisms descended from ancient organisms |
| theory | well-tested, well-supported explanation that unifies a broad range of observations |
| fossil | preserved remains of an ancient organism |
| natural variation | differences among individuals of a species; results from mutation and sexual reproduction |
| struggle for existence | competition between organisms for food and space |
| fitness | ability of an organism to survive and reproduce in its environment |
| adaptation | inherited characteristic that increases an organism's chance of survival |
| survival of the fittest | individuals that are better suited to their environment survive and reproduce most successfully; natural selection |
| natural selection | individuals that are better suited to their environment survive and reproduce most successfully; survival of the fittest |
| common descent | principle that all living things have a common ancestor |
| homologous structure | structures that have different mature forms but develop from the same embryonic tissues |
| vestigial organ | organ so reduced in size, it does not serve an important function; may be homologous to structures in other organisms |
| gene pool | combined genetic information of of all the members of a population |
| allele frequency | how often a form of a gene appears in a gene pool |
| species | two organisms that are so similar they can interbreed in nature and produce fertile offspring |
| speciation | formation of a new species as a result of reproductive isolation |
| reproductive isolation | separation of species that prevents them from interbreeding and producing fertile offspring |
| behavioral isolation | type of reproductive isolation in which two organisms have different mating rituals that prevent them from interbreeding |
| geographic isolation | type of reproductive isolation in which two populations are separated by geographic barries like mountains or bodies of water |
| temporal isolation | type of reproductive isolation in which two organisms reproduce at different times |
| biodiversity | variety of organisms that exist in the biosphere |
| taxonomy | classification of organisms |
| binomial nomenclature | two part scientfic name for an organism; its genus is listed first, followed by its species |
| genus | first part of an organism's scientific name |
| kingdom | second largest taxonomic group; there are six - animalia, plantae, protista, eubacteria, archaebacteria, fungi |
| domain | most inclusive taxonomic group, larger than kingdom; three exist - bacteria, archaea, eukaryota |
| Protista | a single celled plant or animal, ex. amoeba, paramecia, euglena |
| molecular clock | model that uses DNA comparisons to estimate how long two organisms evolved from a common ancestor |
| phylogenetic tree | diagram showing evolutionary relationships of organisms with a common ancestor; resembles a tree |
| cladogram | diagram that shows the evolutionary relationships among organisms based on derived characters; resembles a timeline |
| divergent evolution | pattern of evolution in which two species become more and more dissimilar |
| Fungi | kingdom of heterotrophs that obtain nutrients through absorption, ex. mushrooms, yeasts |
| Eukaryota | domain of organisms that contain nuclei, includes animals, plants, fungi, and protists |
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