Within-generation mutation variance for litter size in inbred mice.

Area of Science:

• Quantitative Genetics
• Evolutionary Biology
• Animal Genetics

Background:

• Inbred strains are crucial for genetic research but can lose variability over time.
• Understanding the balance between mutation accumulation and genetic drift is key to maintaining genetic diversity.

Purpose of the Study:

• To estimate the mutational input of genetic variance per generation (sigma(m)(2)) and additive genetic variance (sigma(a)(2)) in an inbred mouse strain.
• To investigate the dynamics of genetic variability for litter size across 46 generations.

Main Methods:

• Applied a mixed-model analysis using Bayesian methods.
• Analyzed 46 generations of C57BL/6J inbred mice data.
• Separately inferred sigma(m)(2) and sigma(a)(2).

Main Results:

• Additive genetic variance (sigma(a)(2)) decreased rapidly, becoming negligible by generation 10.
• Mutational variance (sigma(m)(2)) was moderate and increased over generations, suggesting continuous uploading of genetic variability.
• Heritability (h(2)) for litter size was 0.045, indicating a significant influence of new mutations.

Conclusions:

• The study successfully separated estimates of sigma(a)(2) and sigma(m)(2) within a mixed-model framework.
• New genetic variability continuously influences the genetic stability of inbred mouse strains.
• The findings highlight the importance of ongoing mutation input in maintaining genetic diversity.