Environmental drivers of shell shape in a freshwater gastropod from small and large lakes

Abstract

AbstractElimia livescens (Menke 1830) is a freshwater gastropod common in the Laurentian Great Lakes region. Geometric morphometric analysis was conducted to determine the variation in shell shape among sites along the shoreline of Lake Michigan (4 sites) and 3 inland lakes on Beaver and Manitou Islands (8 sites) in Michigan, USA. Canonical Variates Analysis (CVA) showed significant variation in shell shape among the sites at inland lakes and those on the Lake Michigan shoreline. Based on shell shape, 82.5% of individual snails could be correctly assigned to their lake of origin, and 62.8% could be correctly assigned to their site of origin. CVA axes were tested for correlations with the environmental variables. Shell shape in E. livescens was correlated most strongly with fetch length and specific conductance. Higher fetch lengths produce higher-energy wave action and may select for individuals with a larger aperture, more globose shape, and lower spire (better for anchorage). Lower fetch lengths produce...