Population structure and connectivity among coastal and freshwater Kelp Gull (Larus dominicanus) populations from Patagonia

Abstract

The genetic identification of evolutionary significant units and information on their connectivitycan be used to design effective management and conservation plans for species of concern.Despite having high dispersal capacity, several seabird species show populationstructure due to both abiotic and biotic barriers to gene flow. The Kelp Gull is the most abundantspecies of gull in the southern hemisphere. In Argentina it reproduces in both marineand freshwater environments, with more than 100,000 breeding pairs following a metapopulationdynamic across 140 colonies in the Atlantic coast of Patagonia. However, little isknown about the demography and connectivity of inland populations. We aim to provideinformation on the connectivity of the largest freshwater colonies (those from Nahuel HuapiLake) with the closest Pacific and Atlantic populations to evaluate if these freshwater coloniesare receiving immigrants from the larger coastal populations. We sampled three geographicregions (Nahuel Huapi Lake and the Atlantic and Pacific coasts) and employed areduced-representation genomic approach to genotype individuals for single-nucleotidepolymorphisms (SNPs). Using clustering and phylogenetic analyses we found three geneticgroups, each corresponding to one of our sampled regions. Individuals from marine environmentsare more closely related to each other than to those from Nahuel Huapi Lake, indicatingthat the latter population constitutes the first freshwater Kelp Gull colony to be identifiedas an evolutionary significant unit in Patagonia.