Patterns of Postnatal Growth in a Laboratory Colony of Peromyscus leucopus

Abstract

Phenotypic variation in postnatal growth was examined in 52 litters of Peromyscus leucopus. Male and female growth trajectories were similar during the preweaning period, but diverged during the postweaning period, and partial compensatory growth was exhibited with smaller weanlings growing more rapidly during the postweaning period. Litter size was not related to growth form, but the sex ratio of a litter affected the growth trajectory, with increasing proportion of males in a litter associated with decreased male growth during the preweaning period and lower male mass at weaning. Maternal mass also was correlated with offspring growth; larger females had offspring that grew rapidly during the postweaning period and attained a higher breeding mass. In addition, loss of mass by mothers during the late preweaning period was correlated with heavier neonate and weaning mass, and faster offspring growth during the early preweaning period. Maternal mass also was associated with litter frequency; heavier females were more likely to become pregnant at postpartum estrus.