Multiple-scale processes shape the population genetics of Tehuelche scallop, Aequipecten tehuelchus, in Northern Patagonia

Abstract

The population genetic structure and oceanographic boundaries to gene flow are relevant for understanding biological connectivity in marine environments. However, the relative contribution of historical (e.g., sea-level change) and recent (e.g., fisheries) processes in shaping current patterns of genetic structure and diversity are commonly unknown. This study focuses in the population genetics of the commercially harvested Tehuelche scallop, Aequipecten tehuelchus. This species presents three morphotypes; tehuelchus, madrynensis, and a non-common variant felipponei, which are meristically differentiated by the number of ribs. The genetic structure of the two main morphotypes (tehuelchus and madrynensis) was studied using microsatellite loci in seven locations of the Argentine coast. Historic demography analyses revealed a trend of population expansion after the last glacial period. Two genetic groups were detected that correspond to morphotypes distributed northward (tehuelchus) and southward (madrynensis) of the Peninsula Valdés tidal front. On the other hand, the lack of genetic differentiation among locations with fishery activity in the northern cluster indicates that the commercially exploited demes may belong to a single genetic stock. As this stock is distributed in waters under federal and provincial jurisdictions, the findings highlight the need to integrate management of the species across political boundaries.