Biochemical variation and shell shape in populations of the fresh-water snail Lymnaea peregra (Mollusca, Gastropoda, Pulmonata) from south-west Ireland

Abstract

Lymnaea peregra was collected at sites, predominantly from the Caha plateau, in south-west Ireland. These included sites investigated by previous workers and found to contain populations with a distinctive pattern of variation in shell-shape. Normally spired populations and non-spired (involuta, sub-involuta) could occur in adjacent loughs in the same watershed. The biochemical variation in some of these populations was investigated using horizontal starch-gel zone electrophoresis. Fourteen biochemical loci were investigated. Although circumscribed by difficulties in collecting and low sample numbers, the investigation showed that the pattern of variation in shell shape was still present and was not correlated or associated with the biochemical variation. While this did not support hypotheses of geographic race formation or incipient speciation, it was in agreement with the current view of variation and speciation in fresh-water pulmonates.