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Evidence for selection on a chordate histocompatibility locus
Marie L Nydam1, Alyssa A Taylor, Anthony W De Tomaso
1Division of Science and Mathematics, Centre College, Danville, Kentucky 40422, USA. marie.nydam@centre.edu
Evolution; International Journal of Organic Evolution
|January 30, 2013
Summary
The study reveals that the FuHC locus in Botryllus schlosseri drives allorecognition and exhibits high polymorphism primarily due to mutation, with evidence of selection acting on this gene.
Area of Science:
- Evolutionary Biology
- Genetics
- Immunology
Background:
- Allorecognition, the ability to distinguish self from non-self, is crucial for reproduction and immunity.
- Polymorphism in allorecognition loci is known in systems like plant self-incompatibility (SI) and vertebrate MHC, but poorly understood outside these.
- The ascidian Botryllus schlosseri uses a single locus, FuHC (Fusion/HistoCompatibility), to determine allorecognition outcomes.
Purpose of the Study:
- To investigate the evolution of polymorphism in the allorecognition locus FuHC in Botryllus schlosseri.
- To determine the relative contributions of mutation and recombination to FuHC polymorphism.
- To assess the role of selection in shaping FuHC variation within and among populations.
Main Methods:
- Molecular variation analysis of the FuHC locus in Botryllus schlosseri populations.
- Comparison of mutation and recombination rates.
- Application of selection statistics and neutrality tests to analyze variation distribution.
Main Results:
- FuHC molecular variation is predominantly found within populations, with minimal differentiation among them.
- Mutation appears to be a more significant driver of FuHC polymorphism than recombination.
- Evidence suggests selection acts on FuHC, but the type of selection (balancing or directional) remains unclear.
Conclusions:
- The FuHC locus in Botryllus schlosseri is highly polymorphic, with variation concentrated within populations.
- Mutation is a key factor in generating FuHC diversity, alongside evidence for selection.
- Further research is needed to elucidate the precise mode of selection acting on this critical allorecognition gene.
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