Fig. 4

Genomic differentiation as shown by PCAs of allele frequencies in either the putatively neutral (a-c) or outlier (d-f) datasets for C. punctatus (a, d), P. angulosus (b, e), and S. granularis (c, f). Letters correspond to the sample sites shown in Fig. 1, with darker shaded letters corresponding to western sites, and lighter shaded letters corresponding to eastern sites