Does Shell shape variation play a role in conservation of the long-lived freshwater bivalve Diplodon chilensis (Bivalvia, Hyriidae)?

YUSSEPPONE, MARIA S.; MÁRQUEZ, FEDERICO; LUQUET, CARLOS M.; BREY, THOMAS; RÍOS DE MOLINA, MARIA C.; ROCCHETTA, IARA

ECOHYDROLOGY

JOHN WILEY & SONS INC

Lugar: New York; Año: 2017

1936-0584

Freshwater bivalves of the order Unionoida display an uncommon phenotypic plasticity with high inter and intra-population morphological variability, which could be advantageous for coping with habitat modifications. However, unionoids have suffered a marked population decline in different parts of the world in the last decades. A decline in some populations of the South American long-lived freshwater mussel Diplodon chilensis as a consequence of habitat deterioration has recently been recorded. We studied ontogenetic allometry and shape variation in shells of D. chilensis from two different sites, Paimun lake and Chimehuin river, North Patagonia, Argentina. Shell-shape shows differences between sites (T- square: 1186.7, permutation P values < 0 .001). Shells from Chimehuin river show less intra-population variability; are more elongated, with the anterior part extended upwards and the posterior part downwards; and show a steeper anterior curvature at the umbo compared to those from Paimún lake. These characteristics make shell shape more streamlined to withstand river current. Furthermore, the extended posterior-ventral part in river shells coincides with higher foot weight (p < 0.01 compared to lake samples) which would improve anchoring to the river rocky-sandy substrate. River shells present a bounded eco-morphotype whereas the higher variability of lake shells includes the ?river eco-morphotype?. Growth is allometric throughout life in both sites and is not sex-dependent. According to our results, the success of river re-population programs using mussels from lake populations may be increased by transplanting selected individuals which show ?river eco-morphotype?.