Effect of background selection (BGS) on molecular diversity within and between populations.

<p>After a BGS episode, deleterious mutations (shown in red) are eliminated together with neutral mutations on the same chromosome, leading to reduced diversity. For illustrative purposes, initial neutral diversity is identical in all cases (A–C). Comparison of cases (A) and (B) shows that different BGS episodes will contribute to populations' genetic differentiation. Comparison of cases (B) and (C) shows that recombination reduces the effect of BGS, maintaining diversity, and reducing linkage disequilibrium (LD) as well as population differentiation (compare final states in [A] and [C]).