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Adaptive evolution of the insulin two-gene system in mouse
Meng-Shin Shiao1, Ben-Yang Liao, Manyuan Long
1Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637, USA.
Genetics
|February 5, 2008
Summary
The mouse insulin gene Ins1 originated ~20 million years ago. Both Ins1 and Ins2 show evidence of positive selection, suggesting adaptive evolution in mouse insulin genes possibly linked to environmental changes.
Area of Science:
- Genomics
- Evolutionary Biology
- Molecular Biology
Background:
- Rodent insulin genes (Ins1 and Ins2) form a two-gene system, with Ins1 arising from Ins2.
- The origin and retention mechanisms of Ins1 remain unclear.
- Understanding the evolutionary pressures on these genes is crucial.
Purpose of the Study:
- To investigate the origin and copy number variation of the insulin gene (Ins1) in rodents.
- To analyze the evolutionary forces acting on both Ins1 and Ins2.
- To explore potential adaptive divergence in the mouse insulin system.
Main Methods:
- Genomic approaches including Southern analyses.
- Sequencing of insulin genes across rodent species.
- Phylogenetic analysis and nucleotide polymorphism examination.
Main Results:
- Ins1 originated approximately 20 million years ago, before the mouse-rat split.
- Both Ins1 and Ins2 are under strong functional constraints in murine species.
- Positive selection was detected in Ins1 and Ins2 gene regions in Mus musculus domesticus populations, with specific amino acid sites identified.
Conclusions:
- The mouse insulin two-gene system exhibits adaptive divergence.
- This divergence may be a response to environmental changes, potentially linked to the thrifty-genotype hypothesis and agricultural development.
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