Fig. 5.
Distribution of the proportions of synonymous polymorphic sites observed per nucleotide in the 12 S-locus flanking genes, according to the six categories of polymorphism: SxA.halleri and SxA.lyrata are the proportion of exclusive derived polymorphic sites in Arabidopsis halleri and A. lyrata, respectively; Sx-hal f-lyr and Sx-lyr f-hal are the proportion of polymorphic sites with a derived allele fixed in one species but still in segregation in the other; “Fixed differences” is the number of positions with different fixed alleles in A. halleri and A. lyrata; and Ss is the proportion of shared polymorphic sites in both species. Shaded boxes indicate the one-tailed 95% confidence intervals for each locus, obtained by simulations under the null hypothesis of no linkage to selected sites. Solid dots indicate the observed values. Thick horizontal lines indicate the median for each distribution.