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Following the Dynamics of Structural Variants in Experimentally Evolved Populations
Published on: February 3, 2023
Nucleotide polymorphism at a gene (Pgi) under balancing selection in a butterfly metapopulation
Christopher W Wheat1, Christoph R Haag, James H Marden
1Department of Biological and Environmental Sciences, University of Helsinki, Finland. chris.wheat@stanfordalumni.org
Molecular Biology and Evolution
|October 2, 2009
Summary
The Glanville fritillary butterfly
Area of Science:
- Evolutionary biology
- Population genetics
- Molecular evolution
Background:
- The Glanville fritillary butterfly (Melitaea cinxia) metapopulation in Finland is well-studied.
- Previous research linked phosphoglucose isomerase (PGI) allozyme genotypes to fitness, suggesting balancing selection.
- The Pgi gene is known to be highly polymorphic.
Purpose of the Study:
- To analyze nucleotide polymorphism within the Pgi gene's coding region in M. cinxia.
- To investigate the molecular basis of balancing selection acting on Pgi.
- To compare Pgi evolution with other metabolic genes and related species.
Main Methods:
- Analysis of nucleotide polymorphism in the Pgi gene's coding region.
- Comparison of Pgi polymorphism with Mdh, Idh, and Gapdh genes.
- Molecular tests for selection and coalescence simulations.
- Comparative structural analysis with Colias eurytheme.
Main Results:
- Pgi exhibits exceptionally high nucleotide polymorphism, unlike other metabolic genes studied.
- Two divergent haplotype clades within Pgi correspond to known allozyme alleles.
- Patterns of polymorphism strongly suggest long-term balancing selection, not neutrality.
- The Pgi divergence predates the common ancestor of five Melitaea species.
- Convergent evolution of Pgi balancing selection is observed between M. cinxia and C. eurytheme.
Conclusions:
- Balancing selection maintains high genetic diversity at the Pgi locus in M. cinxia.
- This balancing selection has operated over long evolutionary timescales.
- Convergent molecular evolution at Pgi suggests similar adaptive pressures in distinct butterfly species.
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