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Microcephaly genes evolved adaptively throughout the evolution of eutherian mammals
Stephen H Montgomery1, Nicholas I Mundy
1Department Genetics, Evolution & Environment, University College London, Gower Street, London WC1E 6BT, UK. Stephen.Montgomery@cantab.net.
BMC Evolutionary Biology
|June 6, 2014
Summary
Genes linked to microcephaly (a neurodevelopmental disorder) show adaptive evolution across mammals, not just primates. Two genes, ASPM and CDK5RAP2, correlate with brain size evolution in diverse mammalian groups.
Area of Science:
- Evolutionary Biology
- Genomics
- Neuroscience
Background:
- Genes associated with microcephaly exhibit adaptive evolution in primates, potentially influencing primate brain size evolution.
- Previous studies suggest adaptive evolution of microcephaly genes in other large-brained mammals like cetaceans.
Purpose of the Study:
- To investigate the evolutionary patterns of seven microcephaly loci across 33 eutherian mammals.
- To determine if positive selection and phenotypic associations with brain size extend beyond primates.
Main Methods:
- Analysis of seven microcephaly loci evolution in 33 eutherian mammals.
- Phylogenetically corrected comparative analyses to correlate gene evolution with neonatal brain size.
Main Results:
- Extensive evidence of positive selection on the majority of microcephaly loci across both primate and non-primate mammals.
- No significant differences in selection patterns were observed across major mammalian clades.
- The evolution of ASPM and CDK5RAP2 genes correlated with neonatal brain size in Glires and Euungulata.
Conclusions:
- ASPM and CDK5RAP2 likely played a consistent role in mammalian brain size evolution.
- Acknowledges limitations including sparse data, averaged evolutionary rates, and potential phenotypic variation/reversals.
- Discusses implications for understanding the genetic basis of brain evolution and testing gene-phenotype hypotheses.
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