Exposure to predation across different time scales alters cortisol levels in guppies

Abstract

Event Abstract Back to Event Exposure to predation across different time scales alters cortisol levels in guppies Eva Kristin Fischer1*, Rayna M. Harris2, Hans A. Hofmann2 and Kim L. Hoke1 1 Colorado State University, Biology Department, United States 2 University of Texas at Austin, Section of Integrative Biology, United States Hormonal responses are inherently plastic, responding to both an organism’s internal and external environment on a time scale from minutes to months. In addition, genetic factors influence hormone levels, making them targets of long-term selective processes. The interactions between genetic and environmental factors in shaping hormonal responses have important implications for individual fitness and adaptive evolution, however, they can rarely be parsed out in natural populations. Due to their well-established role in mediating stress responses, glucocorticoid steroid hormones are often implicated in mediating adaptive shifts in response to environmental stressors, in particular predation pressure. Because differences in predation pressure have repeatedly and independently driven adaptive divergence in the Trinidadian guppy (Poecilia reticulata), we hypothesized that differences in cortisol levels in guppies would reflect differences in evolutionary history with predators and/or life-time exposure to predators. We reared fish from high and low predation source populations with and without exposure to chemical cues of predators and examined baseline cortisol levels and acute cortisol responses using water-borne hormone assays. We first demonstrated that guppies rapidly habituate to sample collection procedures and validated water-borne cortisol results using whole body/water cortisol correlations. We found that both evolutionary history with predators and lifetime exposure to chemical cues of predators decreased baseline cortisol levels. This may be an adaptive shift to reduce the detrimental effects of chronically elevated cortisol that could result from persistent exposure to predators. Similarly, acute exposure to chemical cues of predators reduced excreted cortisol. We are currently exploring whether decreased cortisol excretion reflects decreased internal cortisol levels, or whether guppies actively decrease cortisol excretion in response to predator cues. The fact that evolutionary history with predators and lifetime exposure to predators both decrease cortisol release raises the possibility that adaptive evolutionary changes may co-opt pre-existing responses to environmental changes. This work demonstrates genetic and environmental influences on a hormonal system in a rapidly adapting natural population. Ultimately, we hope to link these hormonal differences to morphological and behavioral differences. Keywords: adaptive evolution, cortisol, Poecilia reticulata, predation Conference: Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012. Presentation Type: Poster (but consider for participant symposium and student poster award) Topic: Hormones and Sex Differences Citation: Fischer E, Harris RM, Hofmann HA and Hoke KL (2012). Exposure to predation across different time scales alters cortisol levels in guppies. Conference Abstract: Tenth International Congress of Neuroethology. doi: 10.3389/conf.fnbeh.2012.27.00385 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: 01 May 2012; Published Online: 07 Jul 2012. * Correspondence: Ms. Eva Kristin Fischer, Colorado State University, Biology Department, Fort Collins, CO, 80521, United States, evakfisch@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Eva Kristin Fischer Rayna M Harris Hans A Hofmann Kim L Hoke Google Eva Kristin Fischer Rayna M Harris Hans A Hofmann Kim L Hoke Google Scholar Eva Kristin Fischer Rayna M Harris Hans A Hofmann Kim L Hoke PubMed Eva Kristin Fischer Rayna M Harris Hans A Hofmann Kim L Hoke Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.