| A | B |
|---|
| biological species concept | efinition of a species as a population or group of populations whose members can breed with one another in nature and produce fertile offspring |
| punctuated equilibrium | evolutionary model suggesting species often diverge in spurts of relatively rapid change, followed by long periods of little change |
| macroevolution | major biological changes evident in the fossil record |
| speciation | formation of new species |
| reproductive isolation | condition in which a reproductive barrier keeps two species from interbreeding |
| geographic isolation | separation of populations as a result of geographic change or migration to geographically isolated places |
| adaptive radiation | evolution from a common ancestor of many species adapted to diverse environments |
| embryology | study of multicellular organisms as they develop from fertilized eggs to fully formed organisms |
| geological time scale | Earth's history organized into four eras: Precambrian, Paleozoic, Mesozoic, and Cenozoic |
| radiometric dating | determination of absolute ages of rocks and fossils through calculations based on a radioactive isotope's fixed rate of decay |
| half life | time it takes for 50 percent of a radioactive isotope sample to decay |
| continental drift | motion of continents about Earth's surface on plates of crust floating on the hot mantle |
| mass extinction | episode of great species loss |
| taxonomy | identification, naming, and classification of species |
| bionomial | two-part Latin name of a species |
| phylogenetic tree | branching diagram, suggesting evolutionary relationships, that classifies species into groups within groups |
| convergent evoluiton | process in which unrelated species from similar environments have adaptations that seem very similar |
| analogous structures | similarities among unrelated species that result from convergent evolution |
| derived character | homologous characteristic that unites organisms as a group |
| cladogram | phylogenetic tree constructed from a series of two-way branch points, suggesting ancestral relationships among species |
