Spatial variations inAlbinaria terebraland snail morphology in Crete (Pulmonata: Clausiliidae): constraints for older and younger colonizations?

Abstract

A spatial approach was employed to test whether the conchological differentiation of the Recent land snailAlbinaria terebrafrom southern central Crete (Greece) is decreased in areas that have been more recently colonized by the species. The eastern Mediterranean genusAlbinariahas produced more than 120 species, probably in pre-Tortonian events of radiation.A. terebraoccupies a compact range of 550 km2consisting partly of late Cenozoic deposits of different ages, partly of pre-Cenozoic formations. The morphological study was based on 300 samples distributed over the entire range of the species. Shell size, shape, whorls, and teleoconch rib densities exhibited no evident correlation with environment but were subjected to considerable spatial variations. The differentiation, determined as the difference of the mentioned shell parameters between one population and another population 2–4 km distant, was found to increase continuously with the time (1–12 Myr) the land has been exposed to air. The populations with the highest degrees of spatial variation came from two areas that have never been submerged in the late Cenozoic, possibly the oldest populations of the species. It is plausible that the other areas were colonized by range expansion after late Neogene periods of tectonic uplift. The results are consistent with previous conclusions derived from molecular studies setting the radiation ofAlbinariaprior to the Tortonian and imply that we might be in possession of a new tool to detect information on the phylogeographic history of land snail species.