Abstract
The exceptionally long (c.11months) growth period of king penguin chicks (Aptenodytes patagonicus) is interrupted by the Austral winter. As a consequence, penguin chicks born late in the breeding season have little time to build-up their energy reserves before the drastic energy bottleneck they experience during winter and face greater risks of mortality than early-born chicks.
Whereas it is well known that breeding adults alternate between early- and late-breeding attempts, little is known on the phenotype of early- and late-chicks, and on the potential existence of specific adaptive phenotypic responses in late-born individuals.
We investigated phenotypic differences between early- and late-chicks and tested their survival correlates both before the winter and at fledgling. Chicks were sampled 10days after hatching to measure body mass, plasma corticosterone levels, oxidative stress parameters and telomere length.
Late-chicks were heavier than early-chicks at day 10. Late-chicks also had higher corticosterone and oxidative stress levels, shorter telomere lengths and suffered from higher mortality rates than early-chicks. For both early- and late-chicks, high body mass close to hatching was a strong predictor of survival up to, and over, the winter period.
In late but not early-chicks, high corticosterone levels and long telomeres were significant predictors of survival up to winter and fledging, respectively.
Our study provides evidence that late- and early-king penguin chicks showed marked phenotypic differences 10days after hatching. We provide an integrative discussion on whether these differences may be adaptive or not, and to what extent they may be driven by active maternal effects, indirectly induced by environmental effects, or stem from individual differences in parental quality.
| Original language | English |
|---|---|
| Pages (from-to) | 601-611 |
| Number of pages | 11 |
| Journal | Functional Ecology |
| Volume | 28 |
| Issue number | 3 |
| Early online date | 17 May 2014 |
| DOIs | |
| Publication status | Published - Jun 2014 |
Bibliographical note
Financial support for this study was provided by the French Polar Institut (IPEV) and the CNRS-INEE. We are grateful to Y. Le Maho and C. Le Bohec for facilitating exchanges between IPEV scientific programs 119 and 137. Special thanks are owed to all field assistants (including M. Kauffmann, M. Ripoche, L. Kernaleguen, B. Gineste & the logistic teams of the Alfred Faure base) for their great efforts during fieldwork, and to G. Lemonnier for providing the king penguin photograph on Fig. 1. We are especially grateful to two anonymous reviewers for providing interesting and constructive comments on a previous draft of the paper, and to G. Earle for editing the English. All procedures were approved by an independent ethics committee commissioned by the French Polar Institute. Working in the colony, handling chicks and sampling was authorized by Terres Australes et Antarctiques Françaises (TAAF). The experiments comply with the current laws of France. AS was supported by a Doctoral Fellowship from the French Ministry of Education, Research and Technology. During the time of writing VAV was supported by a post-doctoral grant from the AXA Research Fund.Keywords
- early-life conditions
- phenotypic plasticity
- oxidative stress
- individual quality
- growth
- telomere
- corticosterone
- reproductive timing