Meeting Abstract
P1.5 Saturday, Jan. 4 15:30 Sociality, Reproductive Condition, and Communication in a Weakly Electric Fish MCNEIL, E.R.*; SKINNER, M.A.; SMITH, G.T.; Indiana Univ.; Indiana Univ.; Indiana Univ. erimcnei@umail.iu.edu
South American knifefishes produce weak electric organ discharges (EODs) for communication and electrolocation. EOD frequency (EODf) varies across species and can signal sex and social rank. Few studies have examined the social ecology of knifefishes, but field and laboratory observations of group size and behavior suggest that some species are territorial, while others live in social groups. We examined changes in signaling during the formation of social groups in Adontosternarchus devenanzii, a sexually monomorphic knifefish species. Fish (n=18) were initially housed individually in 38-l tanks and were moved as a group into three 568-l tanks connected by tubes that allowed movement between tanks. Each tank had two sites with shelter tubes and artificial plants. Food was provided uniformly at all shelter sites. EODf and the location of each fish were measured throughout the study. After 1 month, water conductivity was reduced to induce gonadal recrudescence. The fish formed distinct social groups. During the first week of group housing, fish were evenly distributed across the 6 shelter sites and the 3 tanks (χ2, p=0.48). After 2 weeks, however, most fish aggregated into two shelter sites in one tank (χ2, p<0.001). EODf did not change in response to social housing, but increased significantly when conductivity was reduced (ANOVA, PLSD, p<0.001). EODf was not correlated with mass (r2<0.01, p>0.5). The fish spawned during the experiment, and the fry showed developmental changes in EODf and EOD waveform similar to those in other ghost knifefish. Our results demonstrate that A. devenanzii forms stable social groups, that conductivity and reproductive condition influence EODf, and that EODf is not a reliable signal of body size as it is in some territorial knifefish. ERM and MAS contributed equally. Supported by NSF IOS 0950721.
