Meeting Abstract

P1.54  Friday, Jan. 4  Sex-change in Crepidula cf. marginalis (Gastropoda: Calyptraeidae) is a response to physical contact with conspecifics CARRILLO-BALTODANO, A*; COLLIN, R; Smithsonian Tropical Research Institute, Panama City; Smithsonian Tropical Research Institute, Panama City carbalallan@gmail.com

Interactions with conspecifics commonly influence sex allocation in sequential hermaphrodites, but the cues that trigger sex change in invertebrates have not been examined in detail. In the marine environment waterborne compounds seem the most obvious pathway to established intraspecific communication, but at least in fishes behavioral interactions also play an important role. Previous experiments with several Crepidula species have shown that growth and subsequent sex change of small males appears to be inhibited by association with females or with larger males. When males are raised alone size at sex change was smaller and the time to sex change was faster than males paired with a female. To determine if water-borne cues trigger sex change, pairs of small Crepidula cf. marginalis from Veracruz, Panama, were raised in cups in the laboratory. Thirty replicate males were raised in a cup separated from a female by a 350-micron mesh, to prevent physical interaction but allow food and water to flow between the sides. As a control, males were raised with a female without any obstacle. We found no difference in size or growth rate between males in the two treatments. However, males in the mesh-separated treatment changed sex more quickly than those in the control. More than 50% of these males had changed before any of the individuals in the control began to change. This suggests that physical contact and not water-born cues mediate the effect of conspecifics on sex change in this species.