New DNA sequence variation data for 17 loci corroborate the prior observation from 13 loci that DNA sequence divergence is reduced in genes of low recombination. Two models are presented to estimate t and other relevant parameters (substitution rate correction factors in lineages leading to the island species and, in the case of the 4-parameter model, the ratio of ancestral to extant effective population size) from the multilocus DNA sequence data.
Loci in regions of low recombination have lower divergence within the complex than do other loci, yet divergence from D. melanogaster is similar for both classes. This might reflect gene flow of the low-recombination loci subsequent to initial isolation, but it might also reflect differential effects of changing population size on the two recombination classes of loci when the low-recombination loci are subject to genetic hitchhiking or pseudohitchhiking.
"This 2-parameter model is of potential utility to researchers working on non-model organisms. DNA sequence data at multiple genes are required from the island or otherwise long-term isolated species of interest, its closest mainland ancestor and a third species that is closely related to both (although the island and mainland species must be more closely related to each than either is to the third species)," says Kliman.
"Also, with the number of researchers studying the functional divergence that contributes to speciation (specifically, to decreased fitness of hybrid offspring), getting accurate estimates of isolation times for the Drosophila simulans complex will allow researchers to estimate the rate at which functional divergence accumulated."
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Public Library of Science