Multi-Species Genomic Clines Reveal Cryptic, Pervasive, Climate-Associated Adaptation in the Northwest Atlantic

Researchers have long recognized that climatic variation often drives species distributions in the oceans. Mounting genomic evidence for intra-specific climate associated variation in marine species suggests it may be pervasive across many taxa.  The northwest Atlantic spans one of the steepest marine climatic gradients on Earth, which we hypothesize is a major structuring force for regional populations of marine fish and invertebrates.  We compare genomic evidence for latitudinal and climate based clines in both native and introduced species using published SNP data for Atlantic cod, and Restriction Associated DNA Sequencing (RAD-Seq) datasets for Sea Scallop and the introduced European Green Crab. Remarkably, all three species display similar clines in spatial structure driven by a subset of SNPs (<5%), which all display clear climate associations in allele frequency. The presence of genomic clines in invasive green crab suggests climate-based regulation of invasion success based on differences in pre-existing adaptive divergence among invasions. Our observation of a multispecies cryptic genomic spatial discontinuity driven by environmental conditions, suggests (1) this pattern may be common across broadly-distributed taxa in the region and (2) this genetic analysis may represent a sensitive tool to assess or predict marine climate change impact.