Meeting Abstract
In species that change sex based on social cues, behavioral sex change is rapid and precedes gonadal rearrangement. The precise time course of both rapid and long-term behavioral changes could be highly variable and based largely on group dynamics. In this study, we attempted to better describe the initiation and maintenance of male-typical parenting behavior during protogynous sex change in Lythrypnus dalli, a bidirectional hermaphrodite. These fish live in groups consisting of a dominant male and multiple subordinate females. Male-typical behavior consists of nest defense, courtship jerk swims, and parenting displays involving fanning and rubbing behaviors regardless of egg presence in the nest. We studied these fish under four social contexts. First, in stable social groups consisting of a large male and size mis-matched females, males spent >99% time inside the nest and displayed high rates of parenting, while females spent ~38% time inside the nest, but did not parent. Second, we manipulated the male such that he was in the social group, but did not enter the nest. In this case, the dominant female entered the nest and cannibalized the eggs within the first 30 min, but concurrently displayed parenting and had elevated levels of brain 11-ketotestosterone. Third, we removed the male completely, which triggered a period of hierarchical instability, during which the most dominant female initiated aggression, territoriality, and short bouts of parenting. Fourth, in all female groups, at 5 d, transitioning fish spent ~34% of time inside the nest and exhibited lower parenting rates, while at 10 d, fish spent >70% time in the nest and similar rates of parenting compared to males from stable groups. Future studies will investigate whether similar hormonal mechanisms regulate parenting in males and during protogynous sex change.
