Genetic diversity at synonymous and non-synonymous sites. Genetic diversity (the percentage of sites that differ on average between haplotypes) at synonymous (π
) and nonsynonymous (π
) sites measured at 32 loci in populations of An. gambiae, An. arabiensis and An. melas. Diversity is shown separately for control loci (dark bars) and serpins (pale bars), and is shown for the species as a whole, and for each population separately. Note that although only two individuals (4 haplotypes) were sampled for S-form An. gambiae in population BK, ~19 Kbp of sequence will provide a good estimate of π if mating within the population is random. Diversity was significantly higher in An. gambiae than in An. arabiensis, and significantly lower in An. melas. For non-synonymous sites, serpins had significantly higher diversity than control loci, but this trend was non-significant at synonymous sites. See main text for details, and Additional File 1 for the raw data.