| A | B |
|---|
| biodiversity | Having a number of different species in an area |
| Factors that affect biodiversity in an ecosystem | area, climate, diversity of niches |
| extinction | the disappearance from Earth of a species |
| endangered species | species in danger of becoming extinct in the near future |
| threatened species | species that could become endangered in the near future |
| Human activities that threaten biodiversity | habitat destruction, poaching, pollution, introduction of exotic species |
| habitat destruction | the loss of a natural habitat |
| habitat fragmentation | breaking larger habitats into smaller, isolated pieces or fragments |
| poaching | illegal killing or removal of wildlife species |
| captive breeding | mating of animals in zoos or wildlife preserves to protect biodiversity |
| species | a group of similar organisims that can mate with each other and produce similar offspring |
| Adaptation | a trait that helps an organism survive and reproduce |
| evolution | gradual change in a species over time |
| natural selection | process by which species better adapted to their environment are more likely to survive |
| variation | any difference between individuals of the same species |
| Isolation | complete separation, some members of a species become cut off from the rest of the species |
| what has caused geographic isolation in the past? | continental drift |
| mold | a hollow space in sediment in the shape of an organism |
| fossil record | millions of fossils scientists have collected |
| gradualism | evolution occurs slowly but steadily |
| punctuated equilibria | species evolve during short periods of rapid change |
| What do scientists use to determine evolutionary relationships | body structures, development before birth, DNA sequences |
| homologous structures | similar structures that related species have inherited from a common ancestor |
| branching tree | a diagram that shows how scientists think different groups of organisms are related |
