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Microscopy of Fission Yeast Sexual Lifecycle
Published on: March 9, 2016
Fusion-fission experiments in Aphidius: evolutionary split without isolation in response to environmental bimodality
I Emelianov1, A Hernandes-Lopez, M Torrence
1Plant and Invertebrate Ecology, Rothamsted Research, Harpenden Herts, UK. igor.emelianov@bbsrc.ac.uk
Heredity
|October 7, 2010
Summary
This study provides experimental evidence of selection-gene flow balance in parasitic wasps (Aphidius ervi). Host-based divergence rapidly recovered despite gene flow, demonstrating ecological speciation in action.
Area of Science:
- Evolutionary Biology
- Population Genetics
- Parasitology
Background:
- Understanding host-based divergence is key to host adaptation and ecological speciation in parasites.
- Selection-gene flow balance is often hypothesized in sympatric host races, but experimental proof is limited.
Purpose of the Study:
- To provide direct experimental evidence for the balance between selection and gene flow in maintaining host-based divergence.
- To investigate the genetic underpinnings of host adaptation and ecological speciation in parasitic wasps.
Main Methods:
- A novel fusion-fission method was employed using host races of Aphidius ervi.
- Genetic divergence was initially abolished through hybridization, followed by exposure to a two-host environment under varying gene flow regimes.
- Two replicated experiments with different racial pairs were conducted under contrasting gene flow conditions.
Main Results:
- Host-based genetic divergence (fission) re-evolved within six generations of divergent adaptation, even with continuous gene flow.
- Fission recovery was faster and linkage disequilibrium decayed slower under restricted gene flow (6.7%) compared to unrestricted gene flow.
- Random genetic drift played a minimal role in the observed genetic split.
Conclusions:
- The results provide direct experimental support for a balance between gene flow and divergent selection in driving host-based divergence.
- Ecological speciation can occur rapidly in parasitic insects, even under substantial gene flow.
- Genomic architecture may influence the rates and patterns of divergent evolution.
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