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17 Cards in this Set
- Front
- Back
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definition of a species as a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring but do not produce said offspring with members of other such groups |
biological species concept |
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definition of a species in terms of ecological niche, the sum of how members of the species interact with the nonliving and living parts of their environment |
ecological species concept |
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definition of a species in terms of measurable anatomical criteria |
morphological species concept |
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definition of a species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life |
phylogenetic species concept |
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impede mating or hinder fertilization if mating does occur |
prezygotic barriers |
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prevent a hybrid zygote from developing into a viable fertile adult |
postzygotic barriers |
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two species that occupy different habitats within the same area may encounter each other rarely, if at all, even though they are not isolated by obvious physical barriers, such as mountain ranges |
habitat isolation |
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species that breed during different times of the day, different seasons, or different years cannot mix their gametes |
temporal isolation |
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Courtship rituals that attract mates and other behaviors unique to a species are effective reproductive barriers, even between closely related species |
behavioral isolation |
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mating is attempted, but morphological differences prevent its successful completion |
mechanical isolation |
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Sperm of one species may not be able to fertilize the eggs of another species |
gametic isolation |
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the genes of different parent species may interact in ways that impair the hybrid's development or survival in its environment |
reduced hybrid viability |
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Even if hybrids are vigorous, they may be sterile. If the chromosomes of the two parent species differ in number or structure, meiosis in the hybrids may fail to produce normal gametes. Since the infertile hybrids cannot produce offspring when they mate with either parent species, genes cannot flow freely between species |
reduced hybrid fertility |
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some first-generation hybrids are viable and fertile, but when they mate with one another or with either parent species, offspring of the next generation are feeble or sterile |
hybrid breakdown |
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strengthening of reproductive barriers -- hybrids gradually cease to be formed |
reinforcement |
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weakening of reproductive barriers -- the two species fuse |
fusion |
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continued production of hybrid individuals |
stability |
