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The effect of simultaneous selection on the genetic correlation.
I McMillan1, R W Fairfull, M Quinton
1Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada.
Summary
Simulations show that simultaneous selection affects genetic correlations between traits. Changes in heritability and economic weights can alter the rate of change in genetic correlations over generations.
Area of Science:
- Quantitative Genetics
- Animal Breeding
- Statistical Genetics
Background:
- Genetic correlations influence the response to selection for multiple traits.
- Understanding these correlations is crucial for optimizing breeding programs.
Purpose of the Study:
- To investigate the theoretical impact of simultaneous selection on genetic correlations between two traits over 20 generations.
- To assess how heritability and economic weights influence these changes.
Main Methods:
- Population simulation with 15 loci (5 trait 1, 5 trait 2, 5 pleiotropic).
- Index selection applied based on heritability (h(2)) and economic weights.
- 100 replicates for positive and negative initial correlations.
Main Results:
- Positive initial genetic correlations tended to decline towards zero.
- Negative initial genetic correlations tended to decrease towards -1.
- Unequal heritabilities and economic weights slowed correlation changes, sometimes stabilizing them.
Conclusions:
- Simultaneous selection dynamically alters genetic correlations.
- Parameter changes over time can impact selection effectiveness.
- Static genetic parameter assumptions may negatively affect overall genetic gain.
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