Data from: Seascape genomics reveals fine-scale patterns of dispersal for a reef fish along the ecologically divergent coast of Northwestern Australia

Understanding the drivers of dispersal among populations is a central topic in marine ecology and fundamental for spatially explicit management of marine resources. The extensive coast of Northwestern Australia provides an emerging frontier for implementing new genomic tools to identify patterns of dispersal across diverse and extreme environments. Here we focused on the stripey snapper (Lutjanus carponotatus), which is important to recreational, charter-based, and customary fishers throughout the Indo-West Pacific. We collected 1016 L. carponotatus samples at 51 locations in the coastal waters of Northwestern Australia ranging from the Northern Territory to Shark Bay and adopted a genotype-by-sequencing approach to test whether realized connectivity (via larval dispersal) was related to extreme gradients in coastal hydrodynamics. Hydrodynamic simulations using CONNIE and a more detailed treatment in the Kimberley Bioregion provided null models for comparison. Based on 4,402 polymorphic SNP loci shared across all individuals we demonstrated significant genetic sub-division between the Shark Bay Bioregion in the south and all locations within the five remaining, more northern bioregions. More importantly, we identified a zone of admixture spanning a distance of 180 km at the border of the Kimberley and Canning bioregions, including the Buccaneer Archipelago and adjacent waters, which collectively experiences the largest tropical tidal range and some of the fastest tidal currents in the world. Further testing of the generality of this admixture zone in other shallow water marine species across broader geographic ranges will be critical for our understanding of the population dynamics of marine taxa in our tropical oceans.