Adaptation to Low Salinity Promotes Genomic Divergence in Atlantic Cod (Gadus morhua L.).
Bottom Line: Combining outlier analyses with a landscape genomic approach, we identified a set of directionally selected loci that are strongly correlated with habitat differences in salinity, oxygen, and temperature.We report a suite of outlier single nucleotide polymorphisms within or closely located to genes associated with osmoregulation, as well as genes known to play important roles in the hydration and development of oocytes.These genes are likely to have key functions within a general osmoregulatory framework and are important for the survival of eggs and larvae, contributing to the buildup of reproductive isolation between the low-salinity adapted Baltic cod and the adjacent cod populations.
Affiliation: Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Norway.Show MeSH
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Mentions: In the global outlier analyses comprising all four populations, we identified 123 (1.4%) and 114 (1.3%) SNPs as candidates for divergent selection (log10(Bayes factor [BF]) > 1, empirical P < 0.01), using BAYESCAN and LOSITAN, respectively. Pairwise outlier analyses using BAYESCAN, revealed 228 (2.6%) SNPs as candidates for divergent selection (supplementary fig. S3 and table S4, Supplementary Material online). However, the pattern and the number of outliers in each pairwise comparison varied (fig. 4b–g). In total, 266 SNPs (3.0%) were detected as candidates for divergent selection using global or pairwise outlier test. LG2 and 12 had the highest proportion of SNPs potentially under selection (36 and 98, respectively; supplementary table S4, Supplementary Material online). These two LGs contain large LD blocks, where most, but not all, of these outliers reside (fig. 3).Fig. 4.—
Affiliation: Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Norway.