BIOL 103 Lecture Notes - Lecture 32: Heterochrony, Allometry, Sympatric Speciation
12 Oct 2016
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Potential for them to hybridize = hybrid zones: if hybrids are much lower fitness: Zone remains small or disappears & species remain isolated due to prezygotic isolation: if hybrids are slightly lower fitness: Zone is stable due to continuous gene flow from hybridization of parent species: if hybrids are equal to or superior to parents: Hybrid vigour: gene flow between species homogenizes them. Two species meet up in an intermediate range (ecotone), which is a diff habitat for both species. Hybrids are higher fitness than parental species, but only in ecotone: zone persists. Gene flow will then persist, and longterm selection may promote formation of a new 3rd species. Clines: a change in allele or haplotype frequencies, or in the mean of some phenotypic attribute over space. One thing we expect is to see is a cline occurring across hybrid zones if it is stable (also occur for genetic, morphological and phenotypic traits).
