Selection for environmental variation: a statistical analysis and power calculations to detect response.

Area of Science:

• Animal breeding and genetics
• Quantitative genetics
• Reproductive biology

Background:

• Understanding the genetic basis of variation in traits is crucial for animal breeding.
• Environmental variance, often assumed to be constant, may be influenced by genetic factors.
• Previous studies have primarily used homogeneous variance models.

Purpose of the Study:

• To investigate whether environmental variance in rabbit uterine capacity (litter size) is genetically determined.
• To compare the fit of homogeneous and heterogeneous variance models.
• To propose a selection experiment for modifying environmental variance.

Main Methods:

• Analysis of uterine capacity data in rabbits (litter size).
• Comparison of homogeneous variance (HOM) and heterogeneous variance (HET) mixed linear models.
• Statistical assessment of model fit.
• Derivation of analytical expressions for selection experiments.

Main Results:

• The heterogeneous variance (HET) model showed a better fit to the data than the homogeneous variance (HOM) model.
• Significant additive genetic variance (0.16 [0.10; 0.25]) was found to affect environmental variance.
• A strong negative correlation (-0.74 [-0.90; -0.52]) was observed between genes affecting mean litter size and genes affecting litter size variance.

Conclusions:

• Environmental variance in rabbit litter size is partly genetically determined.
• The HET model provides a more accurate representation of the genetic architecture of litter size.
• A proposed selection criterion and experimental design can be used to modify environmental variance in future breeding programs.