The variance within: stress hormone levels vary and co-vary within but not among individual wild great tits Parus major

A.T. Baugh, K. Van Oers, N. Dingemanse, M. Hau

Research output: Contribution to conferenceAbstractProfessional

Abstract

114.1 BAUGH, A.T.*; VAN OERS, K.; DINGEMANSE, N.; HAU,
M.; Swarthmore College, Netherlands Institute for Ecology, Max
Planck Institute for Ornithology, Max Planck Institute for
Ornithology; abaugh1@swarthmore.edu
The variance within: stress hormone levels vary and co−vary within
but not among individual wild great tits Parus major
Circulating steroid hormones, such as glucocorticoids, can have
diverse and enduring effects on the phenotype and might serve as a
basis for individual differences in hormone−mediated traits. To
understand the extent and basis of variation in the circulating
concentrations of hormones themselves it is important to accurately
decompose within− and among−individual variance components.
Previous research in songbirds suggests that concentrations of
glucocorticoids exhibit individual consistency, but the variance and
covariance of plasma hormones in free−living animals remains
poorly understood. In the present study, we repeatedly captured
individual great tits Parus major from a wild population and
measured their initial and stress−induced plasma corticosterone
(CORT) levels. We evaluated variances and covariances in these
concentrations using a mixed−modeling (character−state) approach.
First, we examined within− and among−individual variances in
initial (CORT0) and stress−induced levels (CORT30) and found little
evidence of repeatability in either measure. Next, we examined the
covariance between CORT0 and CORT30. As predicted, given the
lack of repeatability, we found no among−individual covariance in
these two measuresi.e. average initial levels did not correlate with
average stress−induced levels. We did find, however, strong
within−individual correlations suggesting that an underlying
environmental factor(s) simultaneously modulates changes in initial
and stress−induced levels within the same individual. Together, these
results suggest that plasma glucocorticoid concentrations are
determined principally by acute environmental or state−dependent
factors.
Original languageEnglish
Publication statusPublished - 2014
EventSICB 2014 -
Duration: 01 Apr 2014 → …

Conference

ConferenceSICB 2014
Period01/04/2014 → …

Fingerprint Dive into the research topics of 'The variance within: stress hormone levels vary and co-vary within but not among individual wild great tits Parus major'. Together they form a unique fingerprint.

Cite this