Genetic Analysis Reveals Pockets of Biodiversity at Oceans' Bottoms

By studying the genomes of shrimp-like amphipod Bathycallisoma schellenbergi, which can be found in the deepest parts of the ocean, researchers from Newcastle University have confirmed the presence of genetically isolated pockets of biodiversity in the hadal zone. The findings appear in Science Advances this week. Geographic isolation is a key mechanism in promoting biodiversity and the hadal zone — which extends from 6,000 meters to 11,000 meters deep and is comprised of about 47 fragmented pockets across the world's oceans — is thought to provide the isolated habitats and selective pressures that lead to biologically unique populations. The pan-ocean distribution of some fauna, however, challenges that concept. To investigate, the scientists analyzed the genomes of B. schellenbergi from 12 hadal areas and find that although these organisms can be found across the global, each population is genetically distinct with only limited gene flow between topographically connected hadal regions. "This lack of connectivity suggests that [the] populations are on separate evolutionary trajectories," the study's authors write. Overall, the findings demonstrate "that the shallower ocean floor separating hadal features poses strong barriers to dispersal, driving genetic isolation and creating pockets of diversity to conserve.