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Australian songbird body size tracks climate variation: 82 species over 50 years

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posted on 2019-01-01, 00:00 authored by Janet L Gardner, Tatsuya Amano, Anne Peters, William J Sutherland, Brendan Mackey, Leo Joseph, John Stein, Karen Ikin, Roellen Little, Jesse Smith, Matthew SymondsMatthew Symonds
The observed variation in the body size responses of endotherms to climate change may be explained by two hypotheses: the size increases with climate variability (the starvation resistance hypothesis) and the size shrinks as mean temperatures rise (the heat exchange hypothesis). Across 82 Australian passerine species over 50 years, shrinking was associated with annual mean temperature rise exceeding 0.012°C driven by rising winter temperatures for arid and temperate zone species. We propose the warming winters hypothesis to explain this response. However, where average summer temperatures exceeded 34°C, species experiencing annual rise over 0.0116°C tended towards increasing size. Results suggest a broad-scale physiological response to changing climate, with size trends probably reflecting the relative strength of selection pressures across a climatic regime. Critically, a given amount of temperature change will have varying effects on phenotype depending on the season in which it occurs, masking the generality of size patterns associated with temperature change. Rather than phenotypic plasticity, and assuming body size is heritable, results suggest selective loss or gain of particular phenotypes could generate evolutionary change but may be difficult to detect with current warming rates.

History

Journal

Proceedings of the Royal Society B: biological sciences

Volume

286

Issue

1916

Article number

20192258

Pagination

1 - 10

Publisher

The Royal Society

Location

London, Eng.

ISSN

0962-8452

eISSN

1471-2954

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2019, The Author(s)