| A | B |
|---|
| adaptation | a hereditary characteristic that helps an organism survive and reproduce in its environment |
| species | the most specific of the seven levels of classification; characterized by a group of organisms that can mate with one another to produce fertile offspring |
| evolution | the process by which populations accumulate inherited changes over time |
| fossil | the solidified remains or imprints of once-living organisms |
| fossil record | a historical sequence of life indicated by fossils found in layers of the Earths crust |
| vestigal structure | the remnant of a once-useful anatomical structure |
| trait | distinguishing qualities that can be passed from one generation to another |
| selective breeding | breeding of organisms that have a certain desired trait |
| natural selection | the process by which organisms with favorable traits survive and reproduce at a higher rate than organisms without the favorable trait |
| mutation | a change in the order of the bases in an organisms DNA; deletion, insertion, or substitution |
| generation | time the period between the birth of one generation and the birth of the next generation |
| speciation | the process by which two populations of the same species become so different that they can no longer interbreed |
