Behaviour 2019
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Social Context Modulates Sex-Specific Electrocommunication and Steroid Levels in an Apteronotid Fish  
Megan K. Freiler, G. Troy Smith. Indiana University, Bloomington, IN, United States

Communication signals serve many functions across social context. Hormones often regulate sex-specific differences in signaling. Weakly electric apteronotid fishes communicate with electric organ discharges (EODs). Chirps, brief increases in EOD frequency, are produced during social encounters. Chirping is sexually dimorphic and responsive to steroid hormones. Chirps are often studied in response to playbacks, so conclusions about their function are simplified. Here, we investigate how social experience modifies chirp use and the production of androgens and cortisol in a territorial apteronotid (Apteronotus albifrons). Fish were housed in opposite-sex pairs, same-sex pairs, or in isolation for five weeks and recorded overnight once a week. Blood samples were collected before and after treatment for hormone analysis. There was a strong social novelty response, after which chirp rate declined over five weeks. Although previous studies using playbacks showed males and females have similar chirp rates, we found that chirp rate depended on social context. Chirp rate and habituation were greater in same-sex pairings and varied with status, suggesting chirp function is context-dependent.