Genetic population structure of Crystallichthys matsushimae (Cottoidei: Liparidae) with comments on color variation

Genetic divergence between two color (yellow and red) morphotypes and among regional populations of the liparid Crystallichthys matsushimae were investigated using AFLP and mitochondrial DNA (mtDNA) sequence variations on the partial COI and Cyt-b genes. A principal coordinate analysis (PCoA) based on AFLP data showed a rough separation of the yellow morphotype, distributed in the southern Sea of Japan, from the red morphotype, distributed in the Sea of Okhotsk, northern Sea of Japan and Pacific coast of northern Japan. In addition, both PCoA and the Bayesian-based individual assignment test indicated an extensive population structure among the Sea of Japan, Sea of Okhotsk and Pacific Ocean. In contrast, the mtDNA sequence variations disclosed two haplotype groups, partly corresponding to either the two color morphotypes or the regional populations. However, gene flow restrictions were indicated between both the morphotypes and among the regional populations. Genetic divergence in the mtDNA within C. matsushimae suggested that the color morphotypes and/or regional populations were isolated by sea-level oscillations during the glacial periods. In addition, the discrepancy between the results of AFLP and mtDNA sequencing may be due to the complex history of the species, including introgressive hybridization and gene flow between regional populations as well as a sudden population expansion.