Evolution
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| 563964581 | Species | group of similar organisms that can breed and produce fertile offspring | |
| 563964582 | Endemic | species that is only found in one location on Earth | |
| 563964583 | Gene flow | movement of alleles into or out of a population due to the migration of individuals to or from the population | |
| 563964584 | Hybrid | an organism that is the offspring of genetically dissimilar parents or stock | |
| 563964585 | Natural selection | process by which individuals that are better suited to their environment survive and reproduce most successfully, leading to change in the species over time (evolution) | |
| 563964586 | Evolution | change in a kind of organism over time; process by which modern organisms have descended from ancient organisms | |
| 563964587 | Homologous | having the same evolutionary origin but serving different functions | |
| 563964588 | Analogous | corresponding in function but not in evolutionary origin | |
| 563964589 | Cladogram | a tree diagram used to illustrate phylogenetic relationships | |
| 563964590 | Microevolution | the generation-to-generation change in the frequencies of alleles within a population | |
| 563964591 | Genetic drift | random change in allele frequencies that occurs in small populations | |
| 563964592 | Cline | a graded change in a character along a geographic axis | |
| 563964593 | Hardy-Weinberg equilibrium | theory of a stable, nonevolving population in which frequency of alleles do not change; only occurs in large, isolated populations with random mating, and no natural selection or mutations | |
| 563964594 | Sexual dimorphism | marked differences between the secondary sex characteristics of males and females | |
| 563964595 | Intrasexual selection | A direct competition among individuals of one sex (usually the males in vertebrates) for mates of the opposite sex. | |
| 563964596 | Intersexual selection | Selection whereby individuals of one sex (usually females) are choosy in selecting their mates from individuals of the other sex; also called mate choice. | |
| 563964597 | Macroevolution | evolution on a large scale extending over geologic era and resulting in the formation of new taxonomic groups | |
| 563964598 | Hybrid sterility | A type of postzygotic barrier between species; the species remain isolated because hybrids fail to produce functional gametes. | |
| 563964599 | Hybrid inviability | A type of postzygotic barrier in which hybrid zygotes fail to develop or to reach sexual maturity | |
| 563964600 | Hybrid breakdown | A type of postzygotic barrier in which first-generation hybrids are viable and fertile, but when they mate the offspring are feeble and sterile | |
| 563964601 | Gametic isolation | A type of prezyotic barrier where the sperm of one species may not be able to fertilize the eggs of another species | |
| 563964602 | Prezygotic barrier | A reproductive barrier that impedes mating between species or hinders fertilization if interspecific mating is attempted. | |
| 563964603 | Postzygotic barrier | A reproductive barrier that prevent hybrid zygotes produced by two different species from developing into viable, fertile adults. | |
| 563964604 | Allopatric | occurring in separate locations, describes populations that rarely interbreed because they are separated geographically | |
| 563964605 | Sympatric | occurring in the same or overlapping geographical areas | |
| 563964606 | Heterozygote advantage | Greater reproductive success of heterozygous individuals compared to homozygotes; tends to preserve variation in gene pools. | |
| 563964607 | Behavioral isolation | A prezygotic reproductive barrier in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding | |
| 563964608 | Habitat isolation | A prezygotic reproductive barrier where the species remain isolated because they breed in different habitats. | |
| 563964609 | Endosymbiont theory | The theory that mitochondria, plastids, and chloroplasts, originated as prokaryotic cells engulfed by an ancestral eukaryotic cell. The engulfed cell and its host cell then evolved into a single organism. | |
| 563964610 | Cambrian Explosion | A burst of evolutionary origins when most of the major body plans of animals appeared in a relatively brief time in geologic history; recorded in the fossil record about 545 to 525 million years ago. | |
| 563964611 | Half-life | the period of time in which half of a radioactive substance decays | |
| 563964612 | Vestigial | referring to a functionless structure that was functional in an ancestral species | |
| 563964613 | Uniformitarianism | is the idea that the geologic processes that operate today also operated in the past | |
| 563964614 | Catastrophism | a principle that states that geologic change occurs suddenly | |
| 563964615 | Convergent evolution | process by which unrelated organisms independently evolve similarities when adapting to similar environments | |
| 563964616 | Paleontology | The study of past life on Earth | |
| 563964617 | Punctuated equilibrium | Pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change | |
| 563964618 | Stabilizing selection | natural selection that favors intermediate variants by acting against extreme phenotypes | |
| 563964619 | Directional selection | occurs when natural selection favors one of the extreme variations of a trait | |
| 563964620 | Disruptive selection | natural selection that favors individuals with either extreme of a trait; tends to eliminate intermediate phenotypes | |
| 563964621 | Density-dependent selection | density or frequency of a character determines its relative success based on traits that confer maiting advantages | |
| 564403272 | Biological species concept | a species concept defining a species as a population or group thereof whose members potentially interbreed and produce fertile offspring | |
| 564403273 | Morphological species concept | characterizes a species by body shape and other structural features | |
| 564403274 | Ecological species concept | The idea that ecological roles (niches) define species. | |
| 564403275 | Phylogenetic species concept | A definition of species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life. | |
| 564420119 | Mass extinction | An episode during which large numbers of species become extinct |
