CONICET | Buscador de Institutos y Recursos Humanos

Understanding phenotypic plasticity of species at different spatial scales is vital in the current context of anincreasing pace of environmental changes. Through this knowledge, it is possible to predict their potential to adapt and/orevolve in face of new environmental conditions such as climate change, and/or to understand their ecological range expansion. In Patagonian rocky salt-marshes, one of the most abundant invertebrate species is the scorched mussel Perumytiluspurpuratus. In this system, this mussel can be found inhabiting both vegetated and non-vegetated patches, which differ incritical environmental conditions. We performed a field study evaluating whether mussels growing in vegetated patchesdiffer in shell shape from those growing in adjacent non-vegetated patches. We sampled individuals from both patch typesand assessed their shell shape and size using geometric morphometrics. The results showed that mussels from vegetatedpatches had shells that were more dorsoventrally expanded, anterodorsally restricted and globose in shape than those fromnon-vegetated patches, which showed the opposite traits resulting in a more elongated shell. The differences found could bedriven by the different conditions of temperature, desiccation rate, wave action and population density to which mussels areexposed in each patch type. These results revealed the striking phenotypic plasticity of shell form of this native species at afine-grained scale, which could be one of the explanations for its success in its ecological range expansion.