Feather, but not plasma, glucocorticoid response to artificial light at night differs between urban and forest blue tit nestlings

Dominoni, D. M. , Teo, D., Branston, C. J. , Jakhar, A., Albalawi, B. F. A. and Evans, N. P. (2021) Feather, but not plasma, glucocorticoid response to artificial light at night differs between urban and forest blue tit nestlings. Integrative and Comparative Biology, 61(3), pp. 1111-1121. (doi: 10.1093/icb/icab067) (PMID:34272860) (PMCID:PMC8490687)

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Urbanization drives phenotypic variation in many animal species. This includes behavioral and physiological traits such as activity patterns, aggression, and hormone levels. A current challenge of urban evolutionary ecology is to understand the environmental drivers of phenotypic variation in cities. Moreover, do individuals develop tolerance to urban environmental factors, which underlie adaptative responses and contribute to the evolution of urban populations? Most available evidence comes from correlative studies and rare experiments where a single urban-related environmental factor has been manipulated in the field. Here we present the results of an experiment in which we tested for differences in the glucocorticoid (CORT) response of urban and rural blue tits nestlings (Cyanistes caeruleus) to artificial light at night (ALAN). ALAN has been suggested to alter CORT response in several animal species, but to date no study has investigated whether this effect of ALAN differs between urban and rural populations. Immediately after hatching, urban and forest broods were either exposed to 2 lux of ALAN (using an LED source mounted inside the nestbox) or received no treatment (dark control). The experiment lasted until the chicks fledged. When the chicks were 13 days old plasma samples were collected to measure baseline CORT concentrations, and feather samples to provide an integrative measure of CORT during growth. Forest birds had higher plasma CORT (pCORT) concentrations than their urban counterparts, irrespective of whether they were exposed to ALAN or not. Conversely, we found population-specific responses of feather CORT to ALAN. Specifically, urban birds that received ALAN had increased feather CORT compared with the urban dark controls, while the opposite was true for the forest birds. pCORT concentrations were negatively associated to fledging success, irrespective of population and treatment, while feather CORT was positively associated to fledging success in broods exposed to ALAN, but negatively in the dark control ones. Our results demonstrate that ALAN can play a role in determination of the glucocorticoid phenotype of wild animals, and may thus contribute to phenotypic differences between urban and rural animals.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Evans, Professor Neil and Albalawi, Bedur Faleh A and Dominoni, Dr Davide and Teo, Mr Dylon and Branston, Dr Claire
Authors: Dominoni, D. M., Teo, D., Branston, C. J., Jakhar, A., Albalawi, B. F. A., and Evans, N. P.
College/School:College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
Journal Name:Integrative and Comparative Biology
Publisher:Oxford University Press
ISSN (Online):1557-7023
Published Online:17 July 2021
Copyright Holders:Copyright © The Author(s) 2021
First Published:First published in Integrative and Comparative Biology 61(3): 1111-1121
Publisher Policy:Reproduced under a Creative Commons licence

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
303242Unravelling the impact of artificial light at night on circadian disruption, immunity, and infection riskDavide DominoniNatural Environment Research Council (NERC)NE/S005773/1Institute of Biodiversity, Animal Health and Comparative Medicine