Estimation of changes in genetic parameters in selected lines of mice using REML with an animal model. 2. Body weight, body composition and litter size

Abstract

Restricted Maximum Likelihood (REML) with an animal model was used to estimate genetic parameters of body weight, body consumption and litter size of lines of mice selected for 20 generations on an index of lean mass at 10 weeks in males, highly correlated with body weight, and for a further 18 generations on body weight at 10 weeks in males and females. Univariate and multivariate estimates of heritability were about 0.5 and those of common environment correlations were about 0.25 for both body weight and composition. Body weight and fat pad weight had genetic and phenotypic correlations of about 0.5. The heritability estimate of litter size was about 0.15 from univariate analysis, rather lower from multivariate, and the estimate of its genetic correlation with body weight was about 0.25. There were reductions in heritability of both body weight and litter size in later generations, even though full pedigrees were fitted and inferences made to the base population, but a plateau in response to selection for increased body weight could not be explained by a complete attenuation of genetic variance.

Limits to sustained energy intake. XIV. Heritability of reproductive performance in mice

“…Selection experiments for increased litter size have been performed in various strains of mice and heritability of litter size is estimated to be relatively low at 15% (Beniwal et al, 1992;Gutiérrez et al, 2006;Peripato et al, 2004). In the present study we showed a slight positive relationship (with a slope of 0.16) between litter size of mothers and their biological daughters, but this relationship did not reach significance.…”

“…In the present study we showed a slight positive relationship (with a slope of 0.16) between litter size of mothers and their biological daughters, but this relationship did not reach significance. MF1 mice are known for their relatively large litter sizes and after many generations of selection, generally a selection plateau is observed (Beniwal et al, 1992;Eklund and Bradford, 1977), which may explain the absence of a significant relationship for litter size. The selection plateau is generally attributed to a decrease in genetic variation in later generations, but this may, at least in part, also be attributed to selection limits on SusEI.…”

Natural selection stops the evolution of male attractiveness

“…The few selection experiments that have been designed to determine if the genetic variance evolves under selection (39)(40)(41) have selected on single traits, such as body size, which tend to have higher levels of genetic variance and may only have a weak genetic correlation with fitness (42). Observing changes in genetic variance may therefore require identifying traits under stronger selection than that experienced by individual metric traits.…”

Estimation of changes in genetic parameters in selected lines of mice using REML with an animal model. 1. Lean mass

“…Subsequently selection was practised without replication for body weight, and the analysis of these data, including a discussion of an apparent selection plateau, is described in a second paper (Beniwal et al, 1992).…”