Crustacean cross-roads: Comparative analysis of population connectivity of copepods and euphausiids in the North Atlantic Ocean

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Population connectivity (i.e. exchange of individuals) is an essential characteristic of species, which affects their resilience to external pressures, including climate change and anthropogenic impacts. Spatial structuring and population differentiation of key species in the diverse continental shelf, slope, and open ocean environments across the North Atlantic are critical foundations for ecosystem approaches to fishery management. Use of a standard measure of connectivity, such as DNA sequence divergence of the mitochondrial cytochrome oxidase I (COI) barcode gene, allows comparisons of patterns of connectivity among species and over time. In this study, patterns and pathways of gene flow are characterized and compared for ecologically important North Atlantic species of copepods (e.g. Calanus, Pseudocalanus, Clausocalanus) and euphausiids (e.g. Meganyctiphanes norvegica, Stylocheiron spp.) based on COI sequence variation. Results are discussed for the effects of life history and behaviour, biogeographical distribution, impacts of past climate effects (e.g. bottlenecks with glaciation), and possible responses to recent environmental changes. Future research directions include exploring conceptual and statistical approaches to using population connectivity in the context of ecosystem approaches to fishery management.