Do reproductive strategy and breeding season influence the presence of mate recognition in the intertidal snail Littorina?

Abstract

Summary To test the assumption that littorinid snails do not discriminate between mates prior to copulation, I studied mate recognition behaviour in two species of Littorina on Swedish rocky shores: L. littorea (which has pelagic development and a distinct reproductive season) and L. saxatilis (non-pelagic development; reproduces throughout the year). Copulating pairs were sampled in five populations of each species to determine the occurrence of maladaptive (male-male or male-juvenile) matings. To complement the field sampling I did laboratory experiments on mucous-trail following, to reveal possible discriminating behaviour among potential mates when following mucous trails. In L. littorea about 5% of copulating pairs were between males, while in L. saxatilis, 33–38% were male-male or male-juvenile pairs. In contrast to L. littorea, this study showed that males of L. saxatilis did not discriminate between sexes from mucous trails, but followed any mucous trail (irrespective of sex of marker snail) for longer than females did. Thus, mate recognition behaviour by trail following can explain the difference in the proportion of maladaptive mating pairs between the two species studied. Among the 19 recognized species of the snail Littorina, nine show pelagic larval development, while 10 have direct, non-pelagic development. From the literature a clear relationship between reproductive strategy and the presence or absence of breeding season in Littorina snails was found. Species with pelagic development always have a distinct reproductive season, while species with non-pelagic development either reproduce throughout the year, or show variation between regions in seasonal or non-seasonal reproduction. The hypothesis that reproductive strategy and breeding season may influence the presence of mate recognition in Littorina snails is discussed.