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The types of barriers that can cause this isolation include: different habitats, physical barriers, and a difference in the time of sexual maturity or flowering. [6] [7] An example of the ecological or habitat differences that impede the meeting of potential pairs occurs in two fish species of the family Gasterosteidae (sticklebacks).
For example: If population has the prezygotic isolating allele and the high fitness, post-zygotic alleles and ; and population has the prezygotic allele a and the high fitness, post-zygotic alleles and , both and genotypes will experience recombination in the face of gene flow. Somehow, the populations must be maintained.
Isolation by distance (IBD) is a term used to refer to the accrual of local genetic variation under geographically limited dispersal. [1] The IBD model is useful for determining the distribution of gene frequencies over a geographic region. [2] Both dispersal variance and migration probabilities are variables in this model and both contribute ...
Ecological speciation is a form of speciation arising from reproductive isolation that occurs due to an ecological factor that reduces or eliminates gene flow between two populations of a species. Ecological factors can include changes in the environmental conditions in which a species experiences, such as behavioral changes involving predation ...
Reinforcement assists speciation by selecting against hybrids. 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 ...
Hybrid inviability is a post-zygotic barrier, which reduces a hybrid 's capacity to mature into a healthy, fit adult. [1] The relatively low health of these hybrids relative to pure-breed individuals prevents gene flow between species. Thus, hybrid inviability acts as an isolating mechanism, limiting hybridization and allowing for the ...
Prezygotic incompatibilities - reproductive barrier acting before fertilization. For example, pollinator isolation, mechanical barriers preventing mating, and sperm/ovule incompatibilities that prevent fertilization. Reproductive isolation - the presence of barriers to successful crossbreeding. Barriers can be classified in a number of ways ...
Syntopy is a special case of sympatry. It means the joint occurrence of two species in the same habitat at the same time. Just as the broader term sympatry, "syntopy" is used especially for close species that might hybridise or even be sister species. Sympatric species occur together in the same region, but do not necessarily share the same ...