Genetic variation of the shell morphology in Acanthina monodon (Gastropoda) in habitats with different wave exposure conditions

Abstract

Shell morphology in marine gastropods exhibits high intraspecific variability. Plasticity appears to be the most common response; however, additive genetic variance would explain a significant amount of morphological variance promoting local adaptations. The marine gastropod Acanthina monodon is a direct developer with a low dispersal potential and high variability in shell morphology. Previous studies suggest that adult shell morphology could have an adaptive value that responds to the degree of wave exposure. Given the low dispersal potential of A. monodon and the high temporal predictability of wave exposure conditions at the local scale, it was expected that selection would favour local adaptations with an important component of heritability. To test this hypothesis we estimated shell morphology heritability of A. monodon using pre-hatching juveniles from wave-exposed and wave-sheltered sites along the Chilean coast and using a geometric morphometrics approach. In addition, we compared shell morphology and size of pre-hatching juveniles between exposed and sheltered sites. Heritability of shell morphology was highly variable, ranging between 0.2 and 0.6 among sites. Shell morphology of pre-hatching individuals did not differ between exposed and sheltered conditions. These results suggest that the diversity of shell morphology in adults of A. monodon could be explained by a complex interaction between plastic and heritable responses.