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Reproductive isolation between species appears, in certain cases, a long time after fertilization and the formation of the zygote, as happens – for example – in the twin species Drosophila pavani and D. gaucha. The hybrids between both species are not sterile, in the sense that they produce viable gametes, ovules and spermatozoa.
If their reproductive isolation is incomplete, then further mating between the populations will produce hybrids, which may or may not be fertile. If the hybrids are infertile, or fertile but less fit than their ancestors, then there will be further reproductive isolation and speciation has essentially occurred, as in horses and donkeys. [47]
Taylorella equigenitalis is a Gram-negative bacterium, which grows best under specific environmental conditions on the reproductive organs, and in the reproductive tract of horses. [ 2 ] [ 4 ] [ 9 ] [ 5 ] [ 16 ] [ 17 ] [ 18 ] Taylorella equigenitalis is morphologically identified as coccobacillary [ 2 ] [ 19 ] [ 7 ] [ 14 ] [ 9 ] [ 16 ] [ 17 ...
Reproductive isolation occurs upon the formation of a hybrid zone. In most cases, [citation needed] the hybrid zone is eliminated due to a selective disadvantage. This effectively completes the speciation process. In parapatric speciation, two subpopulations of a species evolve reproductive isolation from one another while continuing to ...
Reinforcement is a process of speciation where natural selection increases the reproductive isolation (further divided to pre-zygotic isolation and post-zygotic isolation) between two populations of species. This occurs as a result of selection acting against the production of hybrid individuals of low fitness.
This occurs when the populations already have some reproductive isolation, but still hybridize to some extent. Because hybridization is costly (e.g. giving birth and raising a weak offspring), natural selection favors strong isolation mechanisms that can avoid such outcome, such as assortative mating. [5]
Reinforcement is a process within speciation where natural selection increases the reproductive isolation between two populations of species by reducing the production of hybrids. [ 1 ] [ 2 ] Evidence for speciation by reinforcement has been gathered since the 1990s, and along with data from comparative studies and laboratory experiments, has ...
Allochronic speciation (also known as allochronic isolation, or temporal isolation) is a form of speciation (specifically ecological speciation) arising from reproductive isolation that occurs due to a change in breeding time that reduces or eliminates gene flow between two populations of a species.