Local adaptation shapes pattern of mitochondrial population structure in Sebastiscus marmoratus

Considering the homogeneity of marine environment, temperature might be a main environmental factor responsible for local adaptation across a wide latitudinal range. We reconstructed population structure and performed selection tests on a fragment of 1821 bp of the mitochondrial ATPase 6 (ATP6) and cytochrome b (CYTB) genes of Sebastiscus marmoratus sampled from five populations throughout the northwest Pacific Ocean across a large latitudinal range. In line with the results of F _st statistics, significant population structure was detected by applying PCoA and STRUCTURE analysis, which showed discrepant genetic patterns compared to previous studies using neutral markers. Selection tests showed that purifying selection was the predominant evolutionary force acting on the analyzed sequences. Valine substitution by Alanine in a single codon 372 in CYTB gene was detected predominantly (93%) in FA population and temperature was a potentially relevant environmental feature. These findings suggest that local adaptation might be shaping the population structure of marbled rockfish. Further, discrepant patterns of population structure suggested that discerning contributions of different mechanisms in shaping and maintaining patterns of population structure is essential to better understand complex population structure and dynamics of marine organisms.