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Evolutionary Process
| Term | Definition |
|---|---|
| adaptation | heritable trait or behavior in an organism that aids in its survival and reproduction in its present environment |
| adaptive radiation | speciation when one species radiates to form several other species |
| allopatric speciation | speciation that occurs via geographic separation |
| allopolyploid | polyploidy formed between two related, but separate specie |
| aneuploidy | condition of a cell having an extra chromosome or missing a chromosome for its species |
| autopolyploid | polyploidy formed within a single species |
| behavioral isolation | type of reproductive isolation that occurs when a specific behavior or lack of one prevents reproduction from taking place |
| convergent evolution | process by which groups of organisms independently evolve to similar forms |
| dispersal | allopatric speciation that occurs when a few members of a species move to a new geographical area |
| divergent evolution | process by which groups of organisms evolve in diverse directions from a common point |
| gametic barrier | prezygotic barrier occurring when closely related individuals of different species mate, but differences in their gamete cells (eggs and sperm) prevent fertilization from taking place |
| gradual speciation model | model that shows how species diverge gradually over time in small steps |
| hybrid | offspring of two closely related individuals, not of the same species |
| hybrid zone | area where two closely related species continue to interact and reproduce, forming hybrids |
| natural selection | reproduction of individuals with favorable genetic traits that survive environmental change because of those traits, leading to evolutionary change |
| postzygotic barrier | reproductive isolation mechanism that occurs after zygote formation |
| prezygotic barrier | reproductive isolation mechanism that occurs before zygote formation |
| punctuated equilibrium | model for rapid speciation that can occur when an event causes a small portion of a population to be cut off from the rest of the population |
| reinforcement | continued speciation divergence between two related species due to low fitness of hybrids between them |
| reproductive isolation | situation that occurs when a species is reproductively independent from other species; behavior, location, or reproductive barriers may cause this to happen |
| speciation | formation of a new species |
| species | group of populations that interbreed and produce fertile offspring |
| sympatric speciation | speciation that occurs in the same geographic space |
| temporal isolation | differences in breeding schedules that can act as a form of prezygotic barrier leading to reproductive isolation |
| variation | genetic differences among individuals in a population |
| vestigial structure | physical structure present in an organism but that has no apparent function and appears to be from a functional structure in a distant ancestor |
| vicariance | allopatric speciation that occurs when something in the environment separates organisms of the same species into separate groups |