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Reinforcement's ubiquity is unknown, [4] but the patterns of reproductive character displacement are found across numerous taxa and is considered to be a common occurrence in nature. [18] Studies of reinforcement in nature often prove difficult, as alternative explanations for the detected patterns can be asserted.
[3]: 354 [4] [5] Differences in behavior or biology that inhibit formation of hybrid zygotes are termed prezygotic isolation. Reinforcement can be shown to be occurring (or to have occurred in the past) by measuring the strength of prezygotic isolation in a sympatric population in comparison to an allopatric population of the same species.
Reinforcement is the deliberate introduction and integration of an organism into an area where its species is already established. [1] This mode of translocation is implemented in populations whose numbers have dropped below critical levels, become dangerously inbred, or who need artificial immigration to maintain genetic diversity. [15]
For example, the secondary contact between Homo sapiens and Neanderthals, as well as the Denisovans, left traces of their genes in modern human. However, if hybridization is so common that the resulting population received significant amount of genetic contribution from both populations, the result should be considered a fusion.
Reinforcement favoring reproductive isolation is required for both parapatric and sympatric speciation. Without reinforcement, the geographic area of contact between different forms of the same species, called their "hybrid zone", will not develop into a boundary between the different species.
Hybrid zones can form from secondary contact. A hybrid zone exists where the ranges of two interbreeding species or diverged intraspecific lineages meet and cross-fertilize. . Hybrid zones can form in situ due to the evolution of a new lineage [1] [page needed] but generally they result from secondary contact of the parental forms after a period of geographic isolation, which allowed their ...
Also called functionalism. The Darwinian view that many or most physiological and behavioral traits of organisms are adaptations that have evolved for specific functions or for specific reasons (as opposed to being byproducts of the evolution of other traits, consequences of biological constraints, or the result of random variation). adaptive radiation The simultaneous or near-simultaneous ...
Brown and Wilson used the term character displacement to refer to instances of both reproductive character displacement, or reinforcement of reproductive barriers, and ecological character displacement driven by competition. [1] As the term character displacement is commonly used, it generally refers to morphological differences due to competition.