Meeting Abstract
95.5 Monday, Jan. 6 14:30 Seasonal Transitions in Reproductive State and Territorial Aggression in Female Siberian Hamsters (Phodopus sungorus) RENDON, N.M.*; DEMAS, G.E.; INDIANA UNIVERSITY, BLOOMINGTON; INDIANA UNIVERSITY, BLOOMINGTON nrendon@indiana.edu
Seasonally breeding rodents exhibit profound physiological and behavioral responses to changing photoperiods, including changes in reproduction and territorial aggression. We have demonstrated increased aggression in Siberian hamsters during short “winter” days (SDs) when reproduction is inhibited, suggesting that changes in aggression are inversely related to gonadal steroids. Short-day gonadally regressed Siberian hamsters experience spontaneous gonadal recrudescence following prolonged exposure to SDs. It is unknown, however, how changes in aggression track changes in reproductive state during these periods of seasonal transition. The goal of this study is to determine aggression in SD regressed, recrudescing, and recrudesced hamsters compared with long-day (LD) animals. To accomplish this, female hamsters were housed in LDs or SDs for 10, 24 or 30 weeks. These times were chosen to capture variation in reproductive state following 1) gonadal regression, 2) initial transition back to a reproductively active state, and 3) full gonadal recrudescence. LD animals maintained reproductive physiology and displayed low levels of aggression across all time points. By week 10, SD animals displayed regressed gonads and high levels of aggression. At week 24, SD animals displayed intermediate levels of both gonadal recrudescence and aggressive behavior. Specifically, those animals that displayed recrudescence had low levels of aggression whereas those that were still regressed maintained high aggression. Full gonadal recrudescence, and a return to LD-like levels of aggression, was predicted by week 30. Collectively, these results broaden our understanding of seasonal adaptation by examining the linkage between aggressive and reproductive seasonal phenotypes.
