Document Type
Article
Publication Title
General and Comparative Endocrinology
Publication Date
4-2022
Keywords
Corticosterone, Cross-fostering, Hatching order, Hatching synchrony, Sex-specific, Troglodytes aedon
Abstract
Variation in nestling growth and survival is often influenced by hatching order, with first-hatched offspring having an advantage over later-hatched younger siblings. In house wrens (Troglodytes aedon), this effect of hatching order is especially evident in asynchronously hatched broods and can lead to sex-specific differences in the size and condition of nestlings. Females appear to allocate the sex of their offspring across the laying order to capitalize on these differences. We hypothesized that levels of circulating corticosterone, the primary metabolic hormone in birds, mediates these sex-specific effects in nestlings. We predicted that: i) baseline levels of corticosterone in nestlings should vary along the hatching order, ii) effects of hatching order on baseline corticosterone should be sex specific, and iii) any sex-specificity of hatching order on baseline corticosterone could be contingent on the degree of hatching synchrony. We tested these predictions in a study in which we measured baseline corticosterone in first- and last-hatched nestlings in synchronously and asynchronously hatching broods. To assess whether any differences in nestling baseline corticosterone levels could be attributed to pre-natal maternal effects, the post-natal environment, or both, we conducted two additional studies in which we measured i) yolk corticosterone in first- and last-laid eggs and ii) baseline corticosterone in nestlings that were cross-fostered to create simulated ‘asynchronously’ hatched broods. There was a significant interaction between sex and relative hatching order in their effects on nestling baseline corticosterone, but no effect of hatching synchrony. Corticosterone levels remained relatively constant across the hatching order in males but decreased in females. There was a significant effect of laying order on yolk corticosterone, with first-laid eggs containing significantly higher levels of yolk corticosterone than last-laid eggs. Cross-fostering of nestlings at different points of development had no significant effect on nestling corticosterone levels. These results indicate that sex-dependent differences in corticosterone levels across the hatching order may arise, at least in part, from embryonic exposure to maternally derived corticosterone, whereas the post-natal rearing environment plays, at best, a minimal role in determining nestling baseline corticosterone levels.
Funding Source
This work was funded by grants from Sigma Xi, the Animal Behavior Society, the American Ornithological Society, the Society for Integrative and Comparative Biology, and the Beta Lambda chapter of the Phi Sigma Biological Sciences Honor Society to MAR, a Faculty Research Award from Illinois State University to SKS, and a grant from the National Institutes of Health (R15HD076308) to SKS and CFT.
Recommended Citation
Rittinger, M.A., Bowden, R.M., Sauers, L.A., Paitz, R.T., Poppe, C.J., Thompson, C.F. and S.K. Sakaluk. 2022. Sex-specific effects of hatching order on nestling baseline corticosterone in a wild songbird. General and Comparative Endocrinology 319: 113964. https://doi.org/10.1016/j.ygcen.2021.113964
DOI
10.1016/j.ygcen.2021.113964
Comments
This is the Accepted Manuscript of an article published in General and Comparative Endocrinology: https://doi.org/10.1016/j.ygcen.2021.113964
First published in General and Comparative Endocrinology: https://doi.org/10.1016/j.ygcen.2021.113964
The raw data are archived in the Mendeley Data Repository: https://doi.org/10.17632/fwrnxp4rfc.1.
Supplemental material available at https://doi.org/10.1016/j.ygcen.2021.113964