Adaptive phenotypic plasticity in a clonal invader

Organisms featuring wide trait variability and occurring in a wide range of habitats, such as the ovoviviparous freshwater New Zealand snail Potamopyrgus antipodarum, are ideal models to study adaptation. Since the mid-19th century, P. antipodarum, characterized by extremely variable shell morphology, has successfully invaded aquatic areas on four continents. Because these obligately and wholy asexual invasive populations harbor low genetic diversity compared to mixed sexual/asexual populations in the native range, we hypothesized that 1) this phenotypic variation in the invasive range might be adaptive with respect to colonization of novel habitats, and 2) that at least some of the variation might be caused by phenotypic plasticity. We surveyed 425 snails from 21 localities across northwest Europe to attempt to disentangle genetic and environmental effects on shell morphology. We analysed brood size as proxy for fitness and shell geometric morphometrics, while controlling for genetic b...