Régulation du développement dimensionnel de la coquille chez trois espèces de Gastéropodes

Abstract

A trend for regulation of shell size buffering the intra-specific variability of growth in three gastropod species. - A striking negative covariance was discovered by S.J. Gould between the intra-specific variations of two geometrical characteristics of gastropods shells : the number of whorls of adult shells and their standard section. This first observation, up to now limited to the endemic genus Cerion, deserves further investigations among other gastropods, including species both phyllogenetically and environmentally distantly related to the genus Cerion. Here, we report on the occurrence of as strong a covariance within three European snails species from both continental (. Pomatias elegans, Cepaea nemoralis ) and marine (Euspira catena) environments. In addition, the speculated functionality attached to this covariance - the regulation and stabilisation of shell (and animal) volumes in spite of the substantial intra-specific variability of the standard section of whorl - was tested and its efficiency confirmed, at least for the studied cases. These results suggest that this negative covariance may well be more common among gastropods than anticipated and encourage more extensive investigations on this respect, throughout the gastropod class.