Fluctuating asymmetry in the shell shape of the Atlantic Patagonian mussel, Mytilus platensis, generated by habitat-specific constraints

TRIVELLINI, MARÍA MAGDALENA; VAN DER MOLEN, SILVINA; FEDERICO MÁRQUEZ,

HYDROBIOLOGIA

SPRINGER

Año: 2018

0018-8158

Fluctuating asymmetry (FA) consists of random deviations from perfect symmetry, andit is a useful trait to monitor developmental stability and ecological stress. The principalgoal in this work was to study shell shape FA in Mytilus platensis as a measure ofstress of living in intertidal wild areas compared to subtidal cultured ones. Shell shapeasymmetry was studied by geometric morphometrics using landmarks andsemilandmarks from internal and external anatomical structures. We analyzed FAcomparing shell shape from 452 individuals living at different habitats (intertidal rockyshores vs. subtidal longlines) in two Patagonian sites. We predict that mussels living inthe intertidal present higher levels of morphological alterations (i.e., FA) than thosefrom the subtidal, where the environmental stress is lower. We based the asymmetryanalysis on the FA scores from Procrustes ANOVA; all effects of the model werestatistically significant. The Procrustes FA scores differed significantly betweenhabitats: intertidal populations presented higher FA scores than subtidal ones. Aspredicted, shell shape in Mytilus platensis is influenced by the habitat and thesedifferences add evidence to the fact that FA is a suitable measure of developmentalinstability, indicating the inability of species to buffer stress in its developmentalpathways.