Low levels of hybridization between sympatric cold-water-adapted Arctic cod and Polar cod in the Beaufort Sea confirm genetic distinctiveness

As marine ecosystems respond to climate change and other stressors, it is necessary evaluate current past hybridization events gain insight on the outcomes drivers of such events. Ancestral introgression within gadids has been suggested allow cod inhabit a variety habitats. Little attention given contemporary hybridization, especially cold-water-adapted ( Boreogadus saida Lepechin, 1774 Arctogadus glacialis Peters, 1872). We used whole-genome, restriction-site associated, mitochondrial sequence data explore degree direction between these species where previous had not reported. Although nearly identical morphologically at certain life stages, we detected very distinct nuclear lineages. one potential hybrid with haplotype genotype, but no early generational hybrids. The presence late generation suggests that least some hybrids survive maturity reproduce. However, historical event could be excluded. Contemporary gene flow appears asymmetrical from into Boreogadus, which may due overlap in timing spawning, environmental heterogeneity, or differences population size. This study provides important baseline information for Alaska environments.