Meeting Abstract

S11-1.6  Monday, Jan. 7  Genetic, Environmental and Social Control of Sex Change in Molluscs COLLIN, R; STRI, Panama collinR@si.edu

Molluscs show a wide diversity of sexual strategies and mechanisms of sex determination. There are both gastropod and bivalve families that are each primarily dioecious, simultaneous hermaphrodites, or sequential hermaphrodites. The multiple evolutionary origins of sex change among molluscs would give power to comparative analyses of the factors associated with this strategy, but data on all but a few groups are too sparse to draw many solid conclusions. However, some generalizations can be drawn. Sex change is primarily protrandrous in gastropods and either protandrous or alternating in bivalves. Many simultaneous hermaphrodites exhibit protandrous simultaneous hermaphroditism. Protandry may be considered an extreme case of this strategy but often occurs in groups that are primarily dioecious and is not so common among clades of simultaneous hermaphrodites. Sex change is associated with a sedentary life-style or limited mobility in gastropods, and possibly with brooding in both gastropods and bivalves? Sex change has been shown experimentally to be environmentally mediated. The timing of or size at sex change responds to interactions with conspecifics as well as environmental factors like food availability and stress. Finally, some evidence indicates that there is a genetic component to an individual’s propensity to change sex.