Meeting Abstract

S11-1.5  Monday, Jan. 7  Environmental influences on plasticity in sexual investment in Daphnia WALSH, M. R.; Univ. of Texas Arlington matthew.walsh@uta.edu

Sex and dormancy are directly connected in organisms that engage in asexual and sexual reproduction. The transition between asexual and sexual reproduction typically results in a dormant stage that provides a mechanism to persist under harsh environmental conditions. For example, many species of Daphnia engage in sexual reproduction when environmental conditions deteriorate and produce resting eggs (ephippia) that remain viable for decades. It has long been assumed that observed variation in the timing and magnitude of sexual investment among populations or species reflects local environmental conditions. Yet, the importance of sex to the persistence of a given population of Daphnia can differ dramatically among habitats (i.e., permanent vs. seasonal ponds). As a result, environmental conditions have the potential to exert selection on sexual investment in Daphnia. In this presentation, I will highlight a growing body of research illustrating an important link between environmental conditions and divergent reproductive strategies in zooplankton. I will specifically: (1) discuss the environmental cues that initiate a transition between asexual and sexual reproduction in Daphnia, and (2) review recent work demonstrating an evolutionary consequence of ecological selective pressures, such as predation and competition, on plasticity in sexual investment in Daphnia.