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Parasites affect song complexity and neural development in a songbird
Karen A Spencer1, Katherine L Buchanan, Stefan Leitner
1School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK. karen.spencer@bristol.ac.uk
Proceedings. Biological Sciences
|September 30, 2005
Summary
Juvenile malaria infection in canaries led to simpler adult songs and smaller song control brain regions. This developmental stress impacts sexually selected traits and brain structure, supporting parasite-mediated sexual selection.
Area of Science:
- Avian biology
- Neuroethology
- Evolutionary biology
Background:
- Female choice is a key driver of song complexity in songbirds.
- The developmental stress hypothesis links early conditions to adult song complexity via brain development.
Purpose of the Study:
- To investigate the impact of juvenile malaria infection on adult song complexity and brain structure in canaries.
- To test the developmental stress hypothesis and its implications for sexual selection.
Main Methods:
- Male canaries were infected with malaria (Plasmodium relictum) during their juvenile stage.
- Adult song complexity and the size of the high vocal centre (HVC) song nucleus were measured and compared between infected and uninfected groups.
Main Results:
- Malaria-infected juvenile canaries developed simpler songs as adults compared to uninfected controls.
- Infected individuals showed reduced development of the HVC song nucleus in the brain.
- Developmental stress directly affected both a sexually selected trait and the underlying neural pathway.
Conclusions:
- Early-life stress, such as malaria infection, can significantly reduce adult song complexity in male canaries.
- This study provides a direct link between developmental stress, brain structure (HVC), and the evolution of complex songs.
- Results support the Hamilton-Zuk hypothesis, suggesting parasites can mediate sexual selection and influence honest advertising through song complexity.
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