Morphology of Elimia livescens (Mollusca: Pleuroceridae) in Indiana, U.S.A. Covaries with environmental variation

摘要

We examined covariation of morphology with local and regional environmental variables in the widespread North American freshwater gastropod Elimia livescens (Menke, 1830). Geometric morphometrics was used to quantify shape of individuals collected at sites in Indiana, U.S.A. We used the Procrustes superimposition method and relative warp analysis to examine variation among individuals. We found that shape of E. livescens covaried significantly with flowing versus non-flowing habitats, drainage area, latitude and longitude, water temperature, conductivity, substrate type, and the presence of woody debris. Individuals with smaller apertures and streamlined shape occurred in smaller watersheds in the southeastern regions of Indiana, and in local habitats with low water flow, low conductivity, large, coarse substrate (rip-rap), low frequency of woody debris, and higher dissolved oxygen. We suggest that morphological variation is an integral part in maintaining a wide distribution and maximizing local success for an aquatic gastropod that occurs in a variety of environments.