Metabolic Scaling of Stress Hormones in Vertebrates

Authors

Clinton D. Francis, California Polytechnic State University, San Luis Obispo
Jeremy W. Donald, Trinity University
Matthew J. Fuxjager, Wake Forest University
Wolfgang Goymann, Max Planck Institute for Ornithology
Michaela Hau, University of Konstanz
Jerry F. Husak, University of St. Thomas
Michele A. Johnson, Trinity University
Bonnie K, Kircher, University of Florida
Rosemary Knapp, University of Oklahoma
Lynn Martin, University of South FloridaFollow

Document Type

Article

Publication Date

6-2018

Digital Object Identifier (DOI)

https://doi.org/10.1093/icb/icy063

Abstract

Glucocorticoids (GCs) are stress hormones that can strongly influence physiology, behavior, and an organism’s ability to cope with environmental change. Despite their importance, and the wealth of studies that have sought to understand how and why GC concentrations vary within species, we do not have a clear understanding of how circulating GC levels vary within and across the major vertebrate clades. New research has proposed that much interspecific variation in GC concentrations can be explained by variation in metabolism and body mass. Specifically, GC concentrations should vary proportionally with mass-specific metabolic rates and, given known scaling relationships between body mass and metabolic rate, GC concentrations should scale to the −1/4 power of body mass and to the power of 1 with mass-specific metabolic rate. Here, we use HormoneBase, the newly compiled database that includes plasma GC concentrations from free-living and unmanipulated vertebrates, to evaluate this hypothesis. Specifically, we explored the relationships between body mass or mass-specific metabolic rate and either baseline or stress-induced GC (cortisol or corticosterone) concentrations in tetrapods. Our phylogenetically-informed models suggest that, whereas the relationship between GC concentrations and body mass across tetrapods and among mammals is close to −1/4 power, this relationship does not exist in amphibians, reptiles, and birds. Moreover, with the exception of a positive association between stress-induced GC concentrations and mass-specific metabolic rate in birds, we found little evidence that GC concentrations are linked to metabolic rate, although the number of species sampled was quite limited for amphibians and somewhat so for reptiles and mammals. Nevertheless, these results stand in contrast to the generally accepted association between the two and suggest that our observed positive association between body mass and GC concentrations may not be due to the well-established link between mass and metabolism. Large-scale comparative approaches can come with drawbacks, such as pooling and pairing observations from separate sources. However, these broad analyses provide an important counterbalance to the majority of studies examining variation in GC concentrations at the population or species level, and can be a powerful approach to testing both long-standing and new questions in biology.

Comments

Complete list of authors: Eliot T. Miller, Laura A. Schoenle, Maren N. Vitousek, Tony D. Williams, Cynthia J. Downs

Was this content written or created while at USF?

Yes

Citation / Publisher Attribution

Integrative & Comparative Biology, v. 58, issue 4, p. 729-738

Scholar Commons Citation

Francis, Clinton D.; Donald, Jeremy W.; Fuxjager, Matthew J.; Goymann, Wolfgang; Hau, Michaela; Husak, Jerry F.; Johnson, Michele A.; Kircher, Bonnie K,; Knapp, Rosemary; and Martin, Lynn, "Metabolic Scaling of Stress Hormones in Vertebrates" (2018). Integrative Biology Faculty and Staff Publications. 463.
https://digitalcommons.usf.edu/bin_facpub/463