Figure 1.

Nascent and old freshwater stickleback populations share parallel patterns of genomic divergence from marine fish. Smoothed, SNP-based F_ST is plotted along the genome in comparisons of mainland coastal marine vs. mainland postglacial Cook Inlet freshwater fish, and for island marine fish vs. freshwater populations that formed after the 1964 earthquake on geographically separated Middleton Island and Montague Island. Of the island populations studied, these freshwater groups [defined by population genetic structure analysis; Figure S1 and Lescak et al. (2015)] showed a pattern of regionalized high genomic divergence on a background of nearly zero divergence from marine fish. Is., island; MiFW, Middleton Island freshwater; MoSW, Montague Island freshwater.