Figure 4.

Expansion of Fig. 3, showing the Russian River contact zone. Populations are sorted by taxon, but population 22 is intermediate in most respects. pop, Population number in study three; n, sample size; H̄, mean heterozygosity (direct count); P, proportion of loci polymorphic; A, number of alleles in 22 allozymic loci; X, fraction of xanthoptica marker alleles present in populations assigned to oregonensis; O, fraction of oregonensis marker alleles in populations assigned to xanthoptica.