High gene flow and lack of genetic structure in the commercially important crab <i>Cancer porteri</i> (Brachyura: Cancridae) along 1,500 km of the Chilean coast revealed by SNP markers

Studying the distribution of genetic diversity and connectivity patterns is crucial for understanding the ecology of marine species and informing fisheries management decisions. Despite the heterogeneity of the Chilean coast, characterized by upwelling zones and biogeographical breaks, specific benthic species display high genetic homogeneity, likely due to high migratory flow facilitated by long planktonic larval duration (PLD). In Chile, the artisanal fishery targets various crustacean species, with the crab <i>Cancer porteri</i>, commonly known as "Jaiba Limón" or lemon crab being one of the important species representing 17% of total brachyuran landings in the last decade. In this study, the population structure, genetic diversity, and gene flow of <i>C. porteri</i> were analyzed, using data from seven different sample sites along 1,500 km of the Chilean coast from two samples in 2014-2015 and five in 2023-2024. Based on variability at 3,532 single-nucleotide polymorphisms (SNPs) in 127 individuals, the results revealed stable genetic diversity in space and time, and a high effective population size, with no evidence of genetic structure among sampling sites. The results suggest that <i>C. porteri</i> constitutes a single large genetic population across the area between 23°37'S and 36°36'S, with high gene flow among sites in both temporal periods. This lack of genetic structure appears to result from the high gene flow among all studied locations, as observed in other cancrid species in the same area. The long PLD, high fecundity and strong offshore advection capacity may contribute to their high dispersal potential, being an important precedent for future management plans for the species, which should also be complemented with studies that better describe demographic and biological aspects of the species.