| A | B |
|---|
| extinction | end of an evolutionary line or the end of a species, family, or larger group of organisms |
| fossil | physical evidence of an organism that lived long ago |
| transitional fossils | an intermediate form that occur between one fossil form and another |
| homologous structures | body parts of different organisms that are different in detail, but similar in general structure and relation to each other |
| vestigial structures | a type of homologous structure that is no longer used as it is in most other organisms that have it |
| species | a group of organisms that can breed with one another and produce fertile offspring in a natural environment |
| speciation | the process by which new species evolve from old ones |
| geogrpahic isolation | a separation of populations so that they do not interbreed because they live in different locations |
| natural selection | the explanation for evolutionary change in which living things with favorable traits survive to reproduce |
| Cladogram | A branching diagram that shows how closely related living things are based on anatomical or genetic evidence |
| mutation | Random changes to DNA in living things that provides variation within a population |
