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Adaptive variation in beach mice produced by two interacting pigmentation genes.
Cynthia C Steiner1, Jesse N Weber, Hopi E Hoekstra
1Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America.
Plos Biology
|August 19, 2007
Summary
Genetic changes in Mc1r and Agouti influence mammal color patterns. These interacting genes drive adaptive cryptic coloration, crucial for camouflage in species like oldfield mice.
Area of Science:
- Evolutionary genetics
- Mammalian pigmentation genetics
Background:
- Ecologically significant morphological variation, like mammal coloration, has a poorly understood genetic basis.
- Adaptive differences in coat color between mammal populations are often driven by natural selection for camouflage.
Purpose of the Study:
- To identify genetic factors underlying adaptive coat color differences between mainland and beach-dwelling oldfield mice (Peromyscus polionotus).
- To investigate the roles of the melanocortin-1 receptor (Mc1r) and Agouti signaling protein (Agouti) in mammalian pigmentation.
Main Methods:
- Genome-wide linkage mapping to identify chromosomal regions associated with pigmentation traits.
- Candidate gene analysis focusing on Mc1r and Agouti.
- Analysis of gene sequence and mRNA expression levels.
Main Results:
- Two major and one minor chromosomal regions significantly associated with pigmentation differences were identified.
- Mc1r and Agouti genes map to independent regions and explain most of the pigmentation variation.
- A derived mutation in Mc1r coding region and increased Agouti mRNA expression contribute to lighter coat color in beach mice.
- Epistatic interaction between Mc1r and Agouti was observed, where Mc1r effects depend on the Agouti allele.
Conclusions:
- Adaptive cryptic coloration in mammals can be controlled by a few interacting genes with major effects.
- Specific genetic changes in Mc1r and Agouti are key drivers of adaptive coat color evolution in oldfield mice.
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