5
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: not found

      Stress physiology as a predictor of survival in Galapagos marine iguanas.

      1 ,

      Proceedings. Biological sciences

      Read this article at

      ScienceOpenPublisherPMC
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Although glucocorticoid hormones are considered important physiological regulators for surviving adverse environmental stimuli (stressors), evidence for such a role is sparse and usually extrapolated from glucocorticoid effects under laboratory, short-term and/or non-emergency conditions. Galápagos marine iguanas (Amblyrhynchus cristatus) provide an excellent model for determining the ultimate function of a glucocorticoid response because susceptibility to starvation induced by El Niño conditions is essentially their only major natural stressor. In a prospective study, we captured 98 adult male marine iguanas and assessed four major components of their glucocorticoid response: baseline corticosterone titres; corticosterone responses to acute stressors (capture and handling); the maximal capacity to secrete corticosterone (via adrenocorticotropin injection); and the ability to terminate corticosterone responses (negative feedback). Several months after collecting initial measurements, weak El Niño conditions affected the Galápagos and 23 iguanas died. The dead iguanas were typified by a reduced efficacy of negative feedback (i.e. poorer post-stress suppression of corticosterone release) compared with surviving iguanas. We found no prior differences between dead and alive iguanas in baseline corticosterone concentrations, responses to acute stressors, nor in capacity to respond. These data suggest that a greater ability to terminate a stress response conferred a survival advantage during starvation.

          Related collections

          Most cited references 20

          • Record: found
          • Abstract: not found
          • Article: not found

          How Do Glucocorticoids Influence Stress Responses? Integrating Permissive, Suppressive, Stimulatory, and Preparative Actions

           R M Sapolsky (2000)
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Physiological stress in ecology: lessons from biomedical research.

             L. Romero (2004)
            Increasingly, levels of the 'stress hormones' cortisol and corticosterone are being used by ecologists as indicators of physiological stress in wild vertebrates. The amplitude of hormonal response is assumed to correlate with the overall health of an animal and, by extension, the health of the population. However, much of what is known about the physiology of stress has been elucidated by the biomedical research community. I summarize five physiological mechanisms that regulate hormone release during stress that should be useful to ecologists and conservationists. Incorporating these physiological mechanisms into the design and interpretation of ecological studies will make these increasingly popular studies of stress in ecological settings more rigorous.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Do baseline glucocorticoids predict fitness?

              Baseline glucocorticoid (cort) levels are increasingly employed as physiological indices of the relative condition or health of individuals and populations. Often, high cort levels are assumed to indicate an individual or population in poor condition and with low relative fitness (the Cort-Fitness Hypothesis). We review empirical support for this assumption, and find that variation in levels of baseline cort is positively, negatively, or non-significantly related to estimates of fitness. These relationships between levels of baseline cort and fitness can vary within populations and can even shift within individuals at different times in their life history. Overall, baseline cort can predict the relative fitness of individuals and populations, but the relationship is not always consistent or present.
                Bookmark

                Author and article information

                Journal
                Proc. Biol. Sci.
                Proceedings. Biological sciences
                1471-2954
                0962-8452
                Oct 22 2010
                : 277
                : 1697
                Affiliations
                [1 ] Department of Biology, Tufts University, Medford, MA 02155, USA. michael.romero@tufts.edu
                Article
                rspb.2010.0678
                10.1098/rspb.2010.0678
                2982063
                20504812

                Comments

                Comment on this article