Androgens regulate differences in chirp duration in the weakly electric fish Parapteronotus hasemani

Abstract

Event Abstract Back to Event Androgens regulate differences in chirp duration in the weakly electric fish Parapteronotus hasemani Jacquelyn Petzold1* and G. Troy Smith1, 2, 3 1 Indiana University - Bloomington, Department of Biology, United States 2 Indiana University - Bloomington, Center for the Integrative Study of Animal Behavior, United States 3 Indiana University - Bloomington, Program in Neuroscience, United States Apteronotid electric fish produce a continuous electric organ discharge (EOD) that functions in electrolocation and communication. The frequency and amplitude of the EOD can be modulated during reproductive and agonistic interactions to produce chirps. In several species, EOD frequency and chirping are sexually dimorphic traits that are regulated by steroid hormones (Zakon & Smith, 2009). However, the signal parameters that differ between the sexes vary greatly among species. We tested how EOD frequency and chirping vary between and within sexes in Parapteronotus hasemani, a species of South American weakly electric fish with extreme sexual dimorphism in body size. We performed playbacks of species-typical EODs to male and female P. hasemani to quantify EOD frequency and chirping. EOD frequency, chirp rate, and chirp amplitude modulation were not sexually dimorphic. However, males produced chirps that were longer in duration than those of females. Thus, chirp duration, but not EOD frequency, is a sexually dimorphic trait that may be used as an honest indicator of sex in P. hasemani. As with sexually dimorphic communication signals in many species, sex differences in EODs and chirping in electric fish are often regulated by androgens (Zakon & Dunlap, 1999). We treated male P. hasemani with the androgen receptor blocker flutamide to test whether androgens maintain male-typical chirp duration. Chirp duration decreased significantly in males treated with flutamide but not in males treated with vehicle. This suggests that sex differences in electrocommunication signals in P. hasemani are likely regulated by activational effects of androgens. Jaw morphology varies substantially among male P. hasemani and may be correlated with age or social status (Cox Fernandes, 2010). To determine whether morphological variation in males was associated with variation in gonadal steroid levels, we measured hormones (11KT, T) and morphology (jaw length, body length, and body mass). Unlike other species of fish that have morphologically distinct classes of males (Bass, 1992), larger males with longer jaws did not have higher concentrations of 11KT. Circulating concentrations of T and 11KT were not correlated with jaw morphology, body size, or EOD frequency in males. Additionally, EOD frequency and chirping were not correlated with jaw length or body size. The lack of a correlation of EOD and chirp parameters with hormone levels or morphological traits in males suggests that these signals may not necessarily serve as reliable indicators of male quality. Acknowledgements Supported by NSF IOS 0950721 and the Indiana University Center for the Integrative Study of Animal Behavior. Keywords: electrocommunication, Hormones, sex differences Conference: Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012. Presentation Type: Poster (but consider for student poster award) Topic: Hormones and Sex Differences Citation: Petzold J and Smith G (2012). Androgens regulate differences in chirp duration in the weakly electric fish Parapteronotus hasemani. Conference Abstract: Tenth International Congress of Neuroethology. doi: 10.3389/conf.fnbeh.2012.27.00336 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 30 Apr 2012; Published Online: 07 Jul 2012. * Correspondence: Ms. Jacquelyn Petzold, Indiana University - Bloomington, Department of Biology, Bloomington, IN, 47405, United States, jpetzold@indiana.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. 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