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9thGr-Biology-Evolut
9th Grade Biology - Evolution Vocabulary
| Term | Definition |
|---|---|
| evolution | change over time; the process by which modern organisms have descended from ancient organisms |
| theory | a well-supported testable explanation of phenomena that have occurred in the natural world |
| fossil | preserved remains of ancient organisms |
| artificial selection | selection by humans for breeding of useful traits from the natural variation among different organisms |
| struggle for existence | competition among members of a species for food, living space, and the other necessities of life |
| 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 | process by which individuals that are better suited to their environment survive and reproduce most successfully; also called natural selection |
| natural selection | process by which individuals that are better suited to their environment survive and reproduce most successfully; also called survival of the fittest |
| descent with modification | principle that each living species has descended, with changes, from other species over time |
| common descent | principle that all living things have a common ancestor |
| homologous structure | structures that have different mature forms in different organisms but develop from the same embryonic tissues |
| vestigial organ | organ that serves no useful function in an organism |
| gene pool | combined genetic information of all the members of a particular population |
| relative frequency | number of times an allele occurs in a gene pool compared with the number of times other alleles occur |
| directional selection | form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve |
| stabilizing selection | form of natural selection by which the center of the curve remains in its current position; occurs when individuals near the center of a distribution curve have higher fitness than individuals at either end. |
| disruptive selection | form of natural selection in which a single curve splits into two; occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle |
| genetic drift | random change in allele frequencies that occurs in small populations |
| founder effect | change in allele frequencies as a result of the migration of a small subgroup of a population |
| genetic equilibrium | situation in which allele frequencies remain constant |
| speciation | formation of new species |
| reproductive isolation | separation of species or populations so that they cannot interbreed and produce fertile offspring |
| behavioral isolation | form of reproductive isolation in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreed. |
| geographic isolation | form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water. |
| temporal isolation | for of reproductive isolation in which two population produce |
| macroevolution | large-scale evolutionary changes that take place over long periods of time. |
| adaptive radiation | process by which a single species or small group of species evolves into several different forms that live in different ways; rapid growth in the diversity of a group of organisms |
| convergent evolution | process by which unrelated organisms independently evolve similarities when adapting to similar environments |
| coevolution | process by which two species evolve in response to changes in each other |
| punctuated equilibrium | pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change |