We suggest fruitful areas of research that might help distinguish between different models. In most cases, reduced gene flow appears to contribute to the pattern, although disentangling the relative contribution of reduced gene flow and selection at linked sites remains a challenge. We find strong support for the prediction that genomic regions experiencing low levels of recombination are more differentiated. We then compare those predictions with empirical data of DNA sequence variation in rabbits and mice. Here, we review both speciation and population-genetic models that make explicit predictions about how the rate of recombination influences patterns of genetic variation within and between species. Along with a growing number of datasets of multi-locus DNA sequence variation, these methods have spawned a renewed interest in speciation models with gene flow. New analytic methods have been developed to help distinguish ancestral polymorphism from migration. Moreover, identifying the actual amount of gene flow from patterns of genetic variation is tricky, because both ancestral polymorphism and migration lead to shared variation between recently diverged taxa. However, several population-genetic models that focus on selection at linked sites also predict greater differentiation in regions of low recombination simply as a result of faster sorting of ancestral alleles even in the absence of gene flow.
no gene flow, mutation, or natural selection.
gene flow that is equal both into and out of the population. a significant mutation rate from generation to generation. strong selection pressure on the trait(s) being studied. A number of models of speciation with gene flow propose that the frequency of gene exchange will be lower in genomic regions of low recombination and that these regions will therefore be more differentiated. polymorphism., Hardy-Weinberg equilibrium assumes: a. Recently diverged taxa may continue to exchange genes.
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