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Hybrid zones can form from secondary contact. A hybrid zone exists where the ranges of two interbreeding species or diverged intraspecific lineages meet and cross-fertilize. . Hybrid zones can form in situ due to the evolution of a new lineage [1] [page needed] but generally they result from secondary contact of the parental forms after a period of geographic isolation, which allowed their ...
A hybrid zone may appear during secondary contact, meaning there would be an area where the two populations cohabitate and produce hybrids, often arranged in a cline. The width of the zone may vary from tens of meters to several hundred kilometers. A hybrid zone may be stable, or it may not.
Hybrizyme is a term coined to indicate novel or normally rare gene variants (or alleles) that are associated with hybrid zones, geographic areas where two related taxa (e.g. species or subspecies) meet, mate, and produce hybrid offspring. [1] The hybrizyme phenomenon is widespread and these alleles occur commonly, if not in all hybrid zones. [2]
A prediction of reinforcement is that assortive mating should be common in hybrid zones; a prediction that was confirmed in 19 of the 37 cases. [6] A survey of the rates of speciation in fish and their associated hybrid zones found similar patterns in sympatry, supporting the occurrence of reinforcement. [68]
It can occur across hybrid zones due to chance, selection or hybrid zone movement. [8] There is evidence that introgression is a ubiquitous phenomenon in plants and animals, [ 9 ] [ 10 ] including humans, [ 11 ] in which it may have introduced the microcephalin D allele.
In other cases, selection may favor multiple and varying phenotypes [26] such as in the case of a mosaic hybrid zone. [31] Natural selection can act on specific alleles both directly or indirectly. [ 29 ] [ 22 ] [ 34 ] In direct selection, the frequency of the selected allele is favored to the extreme.
A tension zone is a transitional zone between two distinctive zones, the zones may be influenced by climatic factors, [1] [2] and geological variation. [ 3 ] creating a floristic tension zone. [ 4 ] A marine tension zone may be affected by variables such as depth, climate or salinity. [ 5 ]
Much-Binding-in-the-Marsh was a comedy show broadcast from 1944 to 1950 and from 1951 to 1954 by BBC Radio, and from 1950 to 1951 by Radio Luxembourg.It was written by and starred Richard Murdoch and Kenneth Horne as officers in a fictional Royal Air Force station coping with red tape and the inconveniences and incongruities of life in the Second World War.