Meeting Abstract

P1.146  Tuesday, Jan. 4  Realistic social experience and social rank influence hormones and communication signals in a weakly electric fish BOHORQUEZ, K.L.*; SMITH, G.T.; Indiana Univ., Bloomington kacree@indiana.edu

Social environment influences behavior and hormone levels in many vertebrates. Weakly electric brown ghost knifefish (Apteronotus leptorhynchus) form small, polygynous social groups (Hagedorn & Heiligenberg, 1985). Housing male A. leptorhynchus with another male increases production of EOD modulations (chirps) and plasma cortisol (F), but not 11-ketotestosterone (11KT) (Dunlap et al., 2002). We investigated the effects of social experience in larger, mixed-sex groups on communication (EODf and chirping) and hormones (F and 11KT). Males and females (n=8 each sex) were bled and EODs and chirps were recorded before and after one week of social housing (4 males + 4 females) or individual housing. Socially housed fish were then tested pairwise in a shelter tube competition assay to determine rank. EODf increased in socially housed males, but decreased in individually housed males (ANOVA p<0.04). Both males and females formed a linear dominance hierarchy, and rank affected 11KT levels in males and chirping in females. Socially housed males and females with lower EODf had higher F (Pearson p<0.02). Rank did not affect F levels (p>0.05). 11KT levels increased in dominant males, but decreased in subordinates (GLM p<0.04). Neither rank nor hormones correlated with EODf or the number of chirps evoked with artificial EOD playback stimuli. In live, dyadic interactions, however, subordinate females chirped more than dominant females (Sign test p<0.03). In males, rank did not affect chirping in the dyadic tests (p>0.05). These results suggest that semi-naturalistic social experience affects electrocommunication signals and hormone levels in A. leptorhynchus, but those effects depend on sex, social rank, and the context in which signals are produced.