Restricting inbreeding while maintaining selection response for weight gain in Mus musculus

Area of Science:

• Animal breeding and genetics
• Quantitative genetics
• Population genetics

Background:

• Minimizing inbreeding is crucial in animal breeding programs to maintain genetic diversity and avoid detrimental effects on fitness.
• Different selection strategies can influence the rate of inbreeding and subsequent genetic responses.
• Understanding the efficiency of various selection methods is key to optimizing breeding outcomes.

Purpose of the Study:

• To evaluate the relative efficiency of three distinct selection methods in minimizing inbreeding depression during artificial selection.
• To compare the impact of individual selection, weighted selection, and minimum coancestry mating on inbreeding levels and fitness traits in mice.

Main Methods:

• A population of common house mice (Mus musculus) was subjected to 17 generations of selection for increased weight gain.
• Mice were randomly assigned to three lines (A, B, C) employing: 1) individual selection with random mating, 2) weighted selection with random mating, and 3) individual selection with minimum coancestry mating.
• Three replicates were maintained for each selection line, with inbreeding levels and fitness traits (intrauterine and birth mortality) recorded.

Main Results:

• All three selection methods achieved similar cumulative selection responses for weight gain.
• Method A (individual selection, random mating) resulted in the highest inbreeding level (31.24%), followed by Method C (27.88%) and Method B (24.72%).
• Lines B (weighted selection) and C (minimum coancestry) exhibited significantly lower deterioration in fitness traits compared to Line A.

Conclusions:

• Weighted selection and minimum coancestry mating are more effective than simple individual selection with random mating at reducing inbreeding rates in mouse populations.
• Lower inbreeding levels achieved through methods B and C correlate with improved reproductive fitness, indicated by reduced intrauterine and birth mortality.
• These findings have implications for designing efficient breeding strategies in livestock and conservation programs to mitigate inbreeding depression.