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Reproductive isolation may be genetic, ecological, [5] behavioral, spatial, or a combination of these. If reproductive isolation fails to establish, the hybrid population may merge with either or both parent species. This will lead to an influx of foreign genes into the parent population, a situation called an introgression. Introgression is a ...
[1] [2] Evidence for speciation by reinforcement has been gathered since the 1990s, and along with data from comparative studies and laboratory experiments, has overcome many of the objections to the theory. [3]: 354 [4] [5] Differences in behavior or biology that inhibit formation of hybrid zygotes are termed
Heterosis or hybrid vigor, on the other hand, is the tendency of outbred strains to exceed both inbred parents in fitness. Selective breeding of plants and animals, including hybridization, began long before there was an understanding of underlying scientific principles.
Nevertheless, in plants, hybridization is a stimulus for the creation of new species – the contrary to the situation in animals. [34] Although the hybrid may be sterile, it can continue to multiply in the wild by asexual reproduction, whether vegetative propagation or apomixis or the production of seeds.
A mule is a sterile hybrid of a male donkey and a female horse.Mules are smaller than horses but stronger than donkeys, making them useful as pack animals.. In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different varieties, subspecies, species or genera through sexual reproduction.
Hybridization without change in chromosome number is called homoploid hybrid speciation. It is considered very rare but has been shown in Heliconius butterflies [ 83 ] and sunflowers . Polyploid speciation, which involves changes in chromosome number, is a more common phenomenon, especially in plant species.
This favors the evolution of greater prezygotic isolation (differences in behavior or biology that inhibit formation of hybrid zygotes). Reinforcement is one of the few cases in which selection can favor an increase in prezygotic isolation, influencing the process of speciation directly. [ 1 ]
Hybrid species are often more vigorous and genetically differed than their ancestors. There are primarily two different forms of hybridization: natural hybridization in an uncontrolled environment, whereas artificial hybridization (or breeding) occurs primarily for the agricultural purposes.