Variation in the Hormonal Stress Response Among Larvae of Three Amphibian Species LISA K. BELDEN 1à , JOHN C. WINGFIELD 2 , AND JOSEPH M. KIESECKER 3 1 Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia 2 Department of Neurobiology, Physiology, and Behavior, University of California, Davis, California 3 The Nature Conservancy, Fort Collins, Colorado In a series of studies, we examined how larval corticosterone treatment for several species of amphibians can impact fitness parameters both during exposure and after metamorphosis. We completed confinement stress series on larvae of three species in natural/semi-natural conditions: wood frogs (Rana sylvatica), Jefferson salamanders (Ambystoma jeffersonianum), and Eastern spadefoot toads (Scaphiopus holbrooki). Two of the species had a typical vertebrate response of increasing corticosterone with confinement. However, Eastern spadefoot toads, which have a very short developmental period before metamorphosis, did not show any increase in corticosterone in response to confinement. In a second study, we treated the three species with a low and a high concentration of corticosterone (0.001 and 0.01 mM dissolved in tank water) in the laboratory and examined effects on growth. Although we were successful in raising baseline corticosterone levels with our high corticosterone concentrations, this did not translate into changes in mean larval growth for any of the three species. The larval treatments also did not appear to translate into differences in the juvenile response to confinement stress after metamorphosis. Although juvenile wood frogs did respond to confinement with increasing corticosterone, there was no variation based on larval treatment. As with the larval responses, the juvenile Eastern spadefoot toads did not have a hormonal response to confinement. In summary, while our larval corticosterone exposures did elevate baseline corticosterone levels, we did not see effects of exposure on growth or any latent effects of larval exposure on juvenile responses to confinement. J. Exp. Zool. 313A, 2010. & 2010 Wiley-Liss, Inc. How to cite this article: Belden LK, Wingfield JC, Kiesecker JM. 2010. Variation in the hormonal stress response among larvae of three amphibian species. J. Exp. Zool. 313A:[page range]. Environmental conditions can have profound effects on developmental trajectories, and can interact strongly with individual genotypes to produce a variety of potential pheno- types. These gene  environment interactions can have especially important consequences during development because they can potentially influence how an organism will respond to conditions for the remainder of the individual’s lifespan. These latent effects, in which conditions during early development influence pheno- types later in life, have been well documented in all vertebrate, and many invertebrate, classes (Pechenik, 2006; Monaghan, 2008). Latent effects can be stimulated by diverse environmental conditions, such as food limitation (e.g. Pechenik et al., 2002) and variation in parental care (e.g. Anisman et al., ’98), and the effects themselves can range from subtle changes in growth, behavior, and physiology to decreased life-spans and fitness. Despite this, there are still relatively few studies that have investigated the underlying mechanisms that are responsible for these effects. Published online in Wiley InterScience (www.interscience.wiley. com). DOI: 10.1002/jez.623 Received 10 March 2010; Revised 22 April 2010; Accepted 28 April 2010 Grant Sponsor: NSF (IBN); Grant numbers: 0131229; 9905679. à Correspondence to: Lisa K. Belden, Department of Biological Sciences, 2119 Derring Hall, Blacksburg, Virginia 24061. E-mail: belden@vt.edu ABSTRACT J. Exp. Zool. 313A, 2010 & 2010 WILEY-LISS, INC. RESEARCH ARTICLE