Dimorphism from an early age : sex differences in size and immune function in great tit nestlings
(2025) In Journal of Avian Biology 2025(6).- Abstract
Birds can show patterns of sexual size dimorphism as early as the nestling stage. This raises the question of how the faster growing sex might reconcile the energetic and nutritional needs of a faster growth rate with resource allocation to other important life functions, such as the development of innate immune function. Innate immunity represents the main line of defence against diseases, and while some innate immune defences are already present at hatching, substantial development occurs throughout the nestling stage. Hence, this development may compete for resource allocation with growth, potentially affecting nestlings in a sex-specific way in species showing sexual size dimorphism at an early age. However, little is known about... (More)
Birds can show patterns of sexual size dimorphism as early as the nestling stage. This raises the question of how the faster growing sex might reconcile the energetic and nutritional needs of a faster growth rate with resource allocation to other important life functions, such as the development of innate immune function. Innate immunity represents the main line of defence against diseases, and while some innate immune defences are already present at hatching, substantial development occurs throughout the nestling stage. Hence, this development may compete for resource allocation with growth, potentially affecting nestlings in a sex-specific way in species showing sexual size dimorphism at an early age. However, little is known about how sex might shape life-history strategies early in the life cycle. In this two-year study, we compared size, mass and immune function (hemolysis-hemagglutination assay, bacteria killing assay and haptoglobin assay) between sexes of great tit Parus major nestlings, likely reflecting the outcome of relative resource allocation during ontogeny. To account for variation in environmental quality, we evaluated sex differences in relation to a brood size manipulation and in relation to seasonal progression. We found that male nestlings grew to a larger size at day 14 than their female siblings. However, we also found some indication that males developed a better immune defense than females, albeit their faster growth. Thus, males manage to invest more heavily in both growth rate and immune defence, probably depending on males being dominant to females in the competition for parental feeding, resulting in higher resource acquisition.
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- author
- Ventura, Sofia ; Liu, Tiancheng ; Broggi, Juli LU ; Nilsson, Jan Åke LU and Hegemann, Arne LU
- organization
- publishing date
- 2025-11
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- avian nestling development, eco-immunology, life-history theory, sexual dimorphism, trade-offs
- in
- Journal of Avian Biology
- volume
- 2025
- issue
- 6
- article number
- 03529
- publisher
- Wiley-Blackwell
- external identifiers
-
- scopus:105024004817
- ISSN
- 0908-8857
- DOI
- 10.1002/jav.03529
- language
- English
- LU publication?
- yes
- additional info
- Publisher Copyright: © 2025 The Author(s). Journal of Avian Biology published by John Wiley & Sons Ltd on behalf of Nordic Society Oikos.
- id
- 3f902c73-0a2c-4872-a14c-b97edf3fa97c
- date added to LUP
- 2026-02-19 15:09:24
- date last changed
- 2026-02-19 15:09:24
@article{3f902c73-0a2c-4872-a14c-b97edf3fa97c,
abstract = {{<p>Birds can show patterns of sexual size dimorphism as early as the nestling stage. This raises the question of how the faster growing sex might reconcile the energetic and nutritional needs of a faster growth rate with resource allocation to other important life functions, such as the development of innate immune function. Innate immunity represents the main line of defence against diseases, and while some innate immune defences are already present at hatching, substantial development occurs throughout the nestling stage. Hence, this development may compete for resource allocation with growth, potentially affecting nestlings in a sex-specific way in species showing sexual size dimorphism at an early age. However, little is known about how sex might shape life-history strategies early in the life cycle. In this two-year study, we compared size, mass and immune function (hemolysis-hemagglutination assay, bacteria killing assay and haptoglobin assay) between sexes of great tit Parus major nestlings, likely reflecting the outcome of relative resource allocation during ontogeny. To account for variation in environmental quality, we evaluated sex differences in relation to a brood size manipulation and in relation to seasonal progression. We found that male nestlings grew to a larger size at day 14 than their female siblings. However, we also found some indication that males developed a better immune defense than females, albeit their faster growth. Thus, males manage to invest more heavily in both growth rate and immune defence, probably depending on males being dominant to females in the competition for parental feeding, resulting in higher resource acquisition.</p>}},
author = {{Ventura, Sofia and Liu, Tiancheng and Broggi, Juli and Nilsson, Jan Åke and Hegemann, Arne}},
issn = {{0908-8857}},
keywords = {{avian nestling development; eco-immunology; life-history theory; sexual dimorphism; trade-offs}},
language = {{eng}},
number = {{6}},
publisher = {{Wiley-Blackwell}},
series = {{Journal of Avian Biology}},
title = {{Dimorphism from an early age : sex differences in size and immune function in great tit nestlings}},
url = {{http://dx.doi.org/10.1002/jav.03529}},
doi = {{10.1002/jav.03529}},
volume = {{2025}},
year = {{2025}},
}