title: Physiological and behavioral effects of exogenous corticosterone in a free-ranging ectotherm.
abstract: In the face of global change, free-ranging organisms are expected to experience more unpredictable stressors. An understanding of how organisms with different life history strategies will respond to such changes is an integral part of biodiversity conservation. Corticosterone (CORT) levels are often used as metrics to assess the population health of wild vertebrates, despite the fact that the stress response and its effects on organismal function are highly variable. Our understanding of the stress response is primarily derived from studies on endotherms, leading to some contention on the effects of chronic stress across and within taxa. We assessed the behavioral and hormonal responses to experimentally elevated stress hormone levels in a free-ranging, arid-adapted ectotherm, the Southern Pacific rattlesnake (Crotalus helleri). Plasma CORT was significantly elevated in CORT-implanted snakes 15days after implantation. Implantation with CORT did not affect testosterone (T) levels or defensive behavior. Interestingly, we observed increased defensive behavior in snakes with more stable daily body temperatures and in snakes with higher plasma T during handling (tubing). Regardless of treatment group, those individuals with lower baseline CORT levels and higher body temperatures tended to exhibit greater increases in CORT levels following a standardized stressor. These results suggest that CORT may not mediate physiological and behavioral trait expression in arid-adapted ectotherms such as rattlesnakes.
authors.affiliation: Biological Sciences Department, California Polytechnic State University, San Luis Obispo, CA 93401, USA. Electronic address: nmclaunch@ufl.edu.
authors.forename: Natalie M
authors.initials: NM
authors.lastname: Claunch
authors.affiliation: Biological Sciences Department, California Polytechnic State University, San Luis Obispo, CA 93401, USA.
authors.forename: Julius A
authors.initials: JA
authors.lastname: Frazier
authors.affiliation: Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
authors.forename: Camilo
authors.initials: C
authors.lastname: Escallón
authors.affiliation: Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
authors.forename: Ben J
authors.initials: BJ
authors.lastname: Vernasco
authors.affiliation: Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
authors.forename: Ignacio T
authors.initials: IT
authors.lastname: Moore
authors.affiliation: Biological Sciences Department, California Polytechnic State University, San Luis Obispo, CA 93401, USA.
authors.forename: Emily N
authors.initials: EN
authors.lastname: Taylor
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D001831:Body Temperature; D003345:Corticosterone / Q000097:blood / Q000494:pharmacology*; D017839:Crotalus / Q000097:blood / Q000502:physiology*; D008297:Male; D013312:Stress, Physiological / Q000187:drug effects; D013739:Testosterone / Q000097:blood
chemical_list: D013739:Testosterone; D003345:Corticosterone
keywords: Corticosterone; Defensive behavior; Ectotherm; Implant; Reptile; Stress; Testosterone