Differential mechanisms for regulation of the stress response across latitudinal gradients

C. W. Breuner, M. Orchinik, T. P. Hahn, S. L. Meddle, I. T. Moore, N. T. Owen-Ashley, T. S. Sperry, J. C. Wingfield

    Research output: Contribution to journalArticlepeer-review

    Abstract

    We examined plasticity of the stress response among three populations of the white-crowned sparrow (Zonotrichia leucophrys). These populations breed at different elevations and latitudes and thus have breeding seasons that differ markedly in length. We hypothesize that in populations where birds raise only one or rarely two broods in a season, the fitness costs of abandoning a nest are substantially larger than in closely related populations that raise up to three broods per season. Thus individuals with short breeding seasons should be less responsive to stressors and therefore less likely to abandon their young. In our study, baseline and handling-induced corticosterone levels were similar among populations, but corticosteroid-binding globulins differed, leading to a direct relationship between stress-induced free corticosteroid levels and length of breeding season. There were also population-specific differences in intracellular low-affinity (glucocorticoid-like) receptors in both liver and brain tissue. Although investigations of population-based differences in glucocorticoid secretion are common, this is the first study to demonstrate population-level differences in binding globulins. These differences could lead to dramatically different physiological and behavioral responses to stress.

    Original languageEnglish
    Pages (from-to)R594-R600
    JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
    Volume285
    Issue number3 54-3
    DOIs
    StatePublished - Sep 1 2003

    Keywords

    • Corticosteroid receptor
    • Corticosteroid-binding globulin
    • Corticosterone
    • Reproduction
    • White-crowned sparrow

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