Maps showing a) sampling locations across Japanese archipelago, of Japan Sea (red) and Pacific Ocean (blue) stickleback distributions; red circles indicate allopatric Japan Sea anadromous, blue circles indicate allopatric Pacific Ocean anadromous, green circles denote sites with both forms present, blue triangles represent Pacific freshwater populations, black square indicates location of Akkeshi system in Eastern Hokkaido; b) sampling sites in the Akkeshi system; c) pruned phylogenetic trees for JS and PO populations where both stable isotope and gill raker data was available based on Nei's D and δμ²; bootstrap values based on 200 bootstrap iterations for JS and PO split are shown at tree root, see S2 for full bootstrap values on full phylogeny; d) mean rates of phenotypic evolution under BM2 (σ²) and OU3 (è) models (± bootstrapped 95% confidence intervals) for gill raker number.