Can a Hybrid Line Break a Selection Limit on Behavioral Evolution in Mice?
Layla Hiramatsu1, Vincent Careau2, Theodore Garland3
1Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA, USA.
Behavior Genetics
|December 5, 2024
Summary
Artificial selection for high running performance in mice reached a limit due to an evolved negative genetic trade-off between running speed and duration. Hybridization did not overcome this limit, highlighting the impact of genetic correlations on evolutionary potential.
Area of Science:
- Evolutionary biology
- Animal behavior genetics
Background:
- Artificial selection for high running performance (HR) in mice resulted in lines reaching apparent selection limits.
- Despite reaching limits, additive genetic variance for running traits was maintained.
Purpose of the Study:
- To investigate changes in additive-genetic variances and covariance of running speed and duration in HR lines.
- To determine if crossing HR lines could break the selection limit.
Main Methods:
- Utilized animal models to analyze genetic variances and covariances after 68 generations of selection.
- Crossed two HR lines and continued directional selection on the hybrid and parental lines for nine generations.
Main Results:
- The genetic correlation between speed and duration evolved from positive to negative in parental HR lines.
- Hybrid lines showed increased heritability for speed and duration but maintained a negative genetic correlation.
- Hybrid mice exhibited heterosis for running distance, but this was transient, and the selection limit was not surpassed.
Conclusions:
- An evolved genetic trade-off between running speed and duration likely explains the inability to break the selection limit.
- Despite renewed genetic variance, the negative correlation between component traits constrained improvements in overall running distance.
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