Meeting Abstract

P2.79  Sunday, Jan. 5 15:30  Sexually dimorphic allometric scaling in the sex changing fish Lythrypnus dalli THOMAS, A.*; SOLOMON-LANE, T.K.; WILLIAMS, M.M.; ROGERS, L.; GROBER, M.S.; Agnes Scott College, Atlanta; Georgia State Univ., Atlanta; Agnes Scott College, Atlanta; Agnes Scott College, Atlanta; Georgia State Univ., Atlanta tsolomonlane1@student.gsu.edu

Allometric relationships frequently differ between males and females and provide insight into the life history of a species. For the bluebanded goby (Lythrypnus dalli), a bidirectionally sex changing fish, sex and size are closely tied to an individual’s social and reproductive role, and as a result, important aspects of allometry may be sexually dimorphic. The L. dalli population is female-biased, and females form harems defended by large, territorial males. Sex is socially regulated such that the dominant fish is always male. With the exception of smaller ‘mini males’ that do not hold territories and utilize an alternative reproductive strategy, subordinates are female. Here, we quantified gonad, liver, and brain mass in field-collected males and females across a range of sizes. There was no overall relationship between gonad and body mass, but gonad mass was positively associated with body mass for males and females separately. As expected, the increase in ovary mass with size was greater than in males because female reproductive success increases with gamete production, while male reproductive success is a function of harem size. Liver mass scaled positively with body mass for males and females, but, corrected for size, females’ livers were approximately 20% larger, suggesting a sex-specific physiological role. Brain mass was positively associated with body mass for all fish together, as well as males and females separately, and the proportional increase in brain size with body size was not different in males and females. These data suggest there can be substantial physiological consequences to being a male vs. female L. dalli.