Potential global distribution of a temperate marine coastal predator: The role of barriers and dispersal corridors on subpopulation connectivity

Predicting the potential distribution of species and possible dispersal corridors at a global scale can contribute to better understanding the availability of suitable habitat to move between, and the potential connectivity between regional distributions. Such information increases knowledge of ecological and biogeographic processes, but also has management applications at a global scale, for example, for estimating the restocking ability of exploited regional subpopulations. As a case study, we tested the utility of environmental niche modeling to investigate the potential global distribution of a highly mobile temperate marine coastal species, the broadnose sevengill shark (Notorynchus cepedianus). First, we characterized and compared three model variants using global data and regional data from two geographically distant and genetically diverging subpopulations in the Southwest Atlantic and southern Australia. The best performing model was then transferred to the rest of the world to obtain a final global prediction for the species. Predictions revealed broad suitable areas across temperate regions of the Northern and Southern Hemispheres. As a final step, we overlaid underwater seamount data on suitability maps to simulate possible dispersal corridors and regional connectivity. Global subpopulation connectivity and dispersal are discussed in the light of recent genetic evidence, to help explain why unoccupied suitable areas are not currently accessed by the species. This study highlights the potential use of global and regional data for the assessment of habitat suitability of species at a global scale, and provides considerations when applying these models to other highly mobile species.