Natural selection helps explain the small range of genetic variation within species
Russell B. Corbett-Detig, Daniel L. Hartl, Timothy B. Sackton
The range of genetic diversity observed within natural populations is much more narrow than expected based on models of neutral molecular evolution. Although the increased efficacy of natural selection in larger populations has been invoked to explain this paradox, to date no tests of this hypothesis have been conducted. Here, we present an analysis of whole-genome polymorphism data and genetic maps from 39 species to estimate for each species the reduction in genetic variation attributable to the operation of natural selection on the genome. We find that species with larger population sizes do in fact show greater reductions in genetic variation. This finding provides the first experimental support for the hypothesis that natural selection contributes to the restricted range of within-species genetic diversity.
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A neat analysis on an important question. The differences in figure 2 make for a nice comparison especially. I do have concerns though about the data in Supp. Table 2. How is it that rice (O. rufipogon or otherwise) is listed as 4m tall but weighing 1.85g? Or a corn plant less than 1g? None of the plant sizes seem to make sense relative to each other.