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Gametic isolation [ edit ] The synchronous spawning of many species of coral in marine reefs means that inter-species hybridization can take place as the gametes of hundreds of individuals of tens of species are liberated into the same water at the same time.
An example of gametic isolation involves the allopatric sea urchins have minimal bindin differences (bindin is a protein involved in the process of sea urchin fertilization, used for species-specific recognition of the egg by the sperm) and have insufficient barriers to fertilization.
Post-mating isolation occurs between the process of copulation (or pollination) and fertilization—also known as gametic isolation. [1]: 232 Some studies involving gametic isolation in Drosophila fruit flies, [93] ground crickets, [94] and Helianthus plants [95] suggest that there may be a role in ecology; however it is undetermined. [4]
The lack of geographic isolation as a definitive barrier between sympatric species has yielded controversy among ecologists, biologists, botanists, and zoologists regarding the validity of the term. As such, researchers have long debated the conditions under which sympatry truly applies, especially with respect to parasitism .
This genetic isolation by distance theory involves concepts of gametic kinship chains, identity by descent, and migration probabilities. The kinship coefficient (φ) is the probability that two homologous loci are identical by descent.
Reinforcement, under his definition, included prezygotic divergence and complete post-zygotic isolation. [18] Servedio and Noor include any detected increase in prezygotic isolation as reinforcement, as long as it is a response to selection against mating between two different species. [4]
Genetic isolation, in combination with diminishing habitat quality and a limited population density, is likely to result in a population's collapse and ultimate extinction. [8] Random mutation rate, drift, high rates of inbreeding, restricted gene flow, and regional extinction have all been shown to increase with isolation.
The concept of common descent is fundamental to the study of evolution, phylogenetics, and cladistics; for instance, all clades, by definition, are rooted in a common ancestor. See also most recent common ancestor. competitive gametic isolation complex trait See quantitative trait. congruent clines consanguineous