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Published on: June 9, 2017
Natural selection in avian protein-coding genes expressed in brain
Erik Axelsson1, Lina Hultin-Rosenberg, Mikael Brandström
1Department of Evolutionary Biology, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden.
Molecular Ecology
|May 17, 2008
Summary
Bird evolution from dinosaurs involved key adaptations like feathers and song. This study reveals accelerated protein evolution in bird-specific genes, particularly those linked to cognitive functions and extravagant plumage, offering insights into avian uniqueness.
Area of Science:
- Evolutionary Biology
- Genomics
- Molecular Evolution
Background:
- Birds evolved from theropod dinosaurs ~150 million years ago.
- Adaptations include feathers, song, and sexual characteristics.
- Molecular basis for these avian adaptations is largely unknown.
Purpose of the Study:
- To investigate the molecular evolutionary background of avian adaptations.
- To identify genes with accelerated protein evolution in birds compared to mammals.
Main Methods:
- Comparative analysis of >5000 protein-coding gene sequences from zebra finch and chicken.
- Calculation of d(N)/d(S) ratios to assess evolutionary rates.
- Alignment with mammalian orthologues to identify bird-specific accelerated genes.
Main Results:
- Genes in the eye and central nervous system showed the lowest evolutionary rates (mean d(N)/d(S) = 0.085).
- Fast-evolving genes are enriched in functions like fertilization, defense, and cognitive processes.
- Identified 228 genes with significantly accelerated protein evolution in birds versus mammals, including those for vocal learning and coloration.
Conclusions:
- Accelerated evolution in specific gene sets underlies unique avian traits.
- Genes involved in cognitive functions and elaborate plumage may be key drivers of avian diversification.
- This study provides a catalogue of candidate genes for avian-specific adaptations.
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