The density of sweeps as a function of the baseline density.

<p>The rate of sweeps per unit map length , plotted against the baseline rate, . The solid line shows , the dashed curve shows the additive approximation given by the solution to Eq. (8) , and the points show simulation results. Different kinds of points represent different values of ; as predicted by the scaling argument, depends on only through . until interference becomes strong at , after which increases only slowly. While the simulated values of continue to increase above Eq. (8) 's “upper limit” of 0.5, they do so only very slowly, remaining even for . (Note that even when Eq. (8) underestimates , it appears that our scaling argument still holds.) Selection and map length are held constant at and while population size and mutation rate are varied. The points show simulation results averaged over generations for (circles), (squares), (diamonds), (upward-pointing triangles), and (downward-pointing triangles). For each value of , values of are shown up the point at which the strength of interference at which the probability of fixation falls to and the neutral accumulation of mutations becomes important (see <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002740#pgen.1002740.s007" target="_blank">Figure S7</a>). The standard errors in the simulation results are less than the size of the points.