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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 process by which natural selection reinforces reproductive isolation. In sympatry, reinforcement increases species discrimination and sexual adaptation in order to avoid maladaptive hybridization and encourage speciation. If hybrid offspring are either sterile or less-fit than non-hybrid offspring, mating between members of ...
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.
Often-cited examples of sympatric speciation are found in insects that become dependent on different host plants in the same area. [38] [39] The best known example of sympatric speciation is that of the cichlids of East Africa inhabiting the Rift Valley lakes, particularly Lake Victoria, Lake Malawi and Lake Tanganyika. There are over 800 ...
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]
An example is the periodical 13- and 17-year Magicicada species. [3] allo-parapatric speciation A mode of speciation where divergence occurs in allopatry and is completed upon secondary contact of the populations--effectively a form of reinforcement. [4] [3] allometry
Pedigree chart Used to show the occurrence of phenotypes of a particular gene or organism and its ancestors from one generation to the next, [ 7 ] [ 8 ] [ 9 ] most commonly humans , show dogs , [ 10 ] and race horses