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The impact of urbanization on body size of Barn Swallows Hirundo rustica gutturalis

Zhao, Yanyan; Liu, Yu; Scordato, Elizabeth S.C.; Lee, Myung‐Bok; Xing, Xiaoying; Pan, Xinyuan; Liu, Yang; Safran, Rebecca J.; Pagani‐Núñez, Emilio


Yanyan Zhao

Yu Liu

Elizabeth S.C. Scordato

Myung‐Bok Lee

Xiaoying Xing

Xinyuan Pan

Yang Liu

Rebecca J. Safran


Urbanization implies a dramatic impact on ecosystems, which may lead to drastic phenotypic differences between urban and nonurban individuals. For instance, urbanization is associated with increased metabolic costs, which may constrain body size, but urbanization also leads to habitat fragmentation, which may favor increases in body mass when for instance it correlates with dispersal capacity. However, this apparent contradiction has rarely been studied. This is particularly evident in China where the urbanization process is currently occurring at an unprecedented scale. Moreover, no study has addressed this issue across large geographical areas encompassing locations in different climates. In this regard, Barn Swallows (Hirundo rustica) are a suitable model to study the impact of urbanization on wild animals because they are a widely distributed species tightly associated with humans. Here, we collected body mass and wing length data for 359 breeding individuals of Barn Swallow (H. r. gutturalis) from 128 sites showing different levels of urbanization around the whole China. Using a set of linear mixed-effects models, we assessed how urbanization and geography influenced body size measured using body mass, wing length, and their regression residuals. Interestingly, we found that the impact of urbanization was sex-dependent, negatively affecting males’ body mass, its regression residuals, and females’ wing length. We also found that northern and western individuals were larger, regarding both body mass and wing length, than southern and eastern individuals. Females were heavier than males, yet males had slightly longer wings than females. Overall, our results showed that body mass of males was particularly sensitive trait to urbanization, latitude, and longitude, while it only showed a weak response to latitude in females. Conversely, while wing length showed a similar geographical pattern, it was only affected by urbanization in the case of females. Further research is needed to determine whether these phenotypic differences are associated with negative effects of urbanization or potential selective advantages.

Journal Article Type Article
Acceptance Date Nov 13, 2020
Online Publication Date Dec 19, 2020
Publication Date 2021-01
Deposit Date Nov 2, 2022
Publicly Available Date Nov 2, 2022
Journal Ecology and Evolution
Electronic ISSN 2045-7758
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 11
Issue 1
Pages 612-625
Keywords body size, China, latitude, longitude, sex differences, urbanization
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