Integrating genetic connectivity and local adaptation in effective Marine Protected Area design: a case study on Southern Ocean Trematomus fishes.

Polar ecosystems support a distinctive, cold-adapted biodiversity that faces significant threats from rapid environmental changes and escalating human impacts. To effectively manage and conserve these living resources, multi-scale data on connectivity and adaptation are essential. Marine protected areas (MPAs) are most effective when designed as interconnected networks that account for both functional diversity and connectivity within and among species. In this study, 607 individuals from ten Trematomus species were analyzed through ddRAD sequencing, yielding thousands of genomic markers to examine patterns of divergence and connectivity on the Southern Ocean shelf, both within and between species. Genomic SNPs showing evidence of selection, identified as "outlier loci," were further analyzed to explore potential local adaptations to varying environmental conditions. Population structure analyses of four species — T. loennbergii, T. eulepidotus, T. scotti, and T. newnesi — indicate extensive dispersal across the Weddell Sea and along the West Antarctic coast, likely facilitated by the Weddell Sea Gyre and the Antarctic Coastal Current. A genetic discontinuity was detected near the Filchner Trough in several species, likely due to the strong outflow from the Filchner-Ronne ice shelf, which may isolate the trough region from the broader Weddell Sea habitat. Additionally, evidence of previously unrecognized cryptic diversity was observed in T. eulepidotus and T. loennbergii. These findings contribute to our understanding of diversity, connectivity, and adaptation on the Southern Ocean shelf, a critical foundation for conservation amid unprecedented global change.

Abstract of an Oral Presentation or a Poster