Neutral and adaptive loci reveal fine-scale population structure in Eleginops maclovinus from North Patagonia

Patagonia is an understudied area, especially when it comes to population genomic studies with relevance to fishery management. However, the dynamic and heterogeneous landscape in this area can harbor important but cryptic genetic population structure. Once such information is revealed, it can be integrated into the management of infrequently investigated species. Eleginops maclovinus is a protandrous hermaphrodite species with economic importance for local communities that is currently managed as a single genetic unit. In this study, we sampled five locations distributed across a salinity cline from Northern Patagonia to investigate the genetic population structure of E. maclovinus. We use Restriction-site Associated DNA (RAD) sequencing and outlier tests to obtain 11,712 neutral, 338 adaptive loci, and 78 loci associated to environmental variables. We identified a spatial pattern of structuration with gene flow and spatial selection by environmental association. Neutral and adaptive loci showed two and three genetic groups, respectively. The effective population sizes estimated ranged from 572 to 14,454 and were influenced more by locality than salinity cline. We found loci putatively associated with salinity suggesting that salinity may act as a selective driver in E. maclovinus populations. These results suggest a complex interaction between genetic drift, geneflow, and natural selection in this area. Our findings suggest that at least two to three genetic units exist in this area, and the information should be integrated into the management of this species. We discuss the significance of these results for fishery management and suggest future directions to improve our understanding of how E. maclovinus is adapted to the dynamic waters of Northern Patagonia.