Genetic structures and divergent loci in the Natural Populations of Walleye Pollock, Theragra chalcogramma

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Theragra chalcogramma, a walleye pollock has widespread geographical distributions and exploitsdifferent ecological niches from extremely low temperature to variable temperature oceans. Thepopulations from latitudinal gradient provide natural replication to study on the evolutionaryresponse towards the environmental gradients. A new method which targeting the SNP markers inISSR region across the genome were used to study the population structure and divergent loci inpollock from Bering Sea and Japans’ ocean. A total of 160 SNP loci were obtained from the adoptedmethod and population divergence and structuring were observed in both populations, confirmingthe existence of genetic break between populations (FST: 0.05–0.07). The evidence of outlier SNPsenhanced the dramatic divergence between Bering Sea and Japan oceans’ populations (FST: 0.183-0.625). A correlation study of allele frequencies at each SNP locus with environmental parametersshowed the occurrence of two outliers SNPs, which might respond to an ocean temperature andsalinity gradients in the populations. Further investigation of outliers SNP by BLAST were positionedthe loci near to a gene which play a vital role in transcription of major histocompatibility (MHC) gene,an evolutionary conserved gene in adaptive immune system in vertebrates which might explained theselection on the gene.