Figure 4.

Sliding window analysis of the gene DMI1. Polymorphism was analysed in 500 nucleotide-long windows with 50 nucleotide steps along the alignments. Displayed statistics are: S, the number of polymorphic sites per window, non-synonymous polymorphism given by Watterson's θ per non-synonymous site, F_ST given by Weir and Cockerham's estimator [59] and Tajima's D computed in both groups. The grey frames denote the positions of exons and the arrowheads mark the position of the sites found with high posterior probability (> 0.95) to be targets of positive selection in the Medicago genus.