Intraspecific variation in body size, metabolic rate, and reproduction of deer mice (Peromyscus maniculatus)

Abstract

Deer mice (Peromyscus maniculatus) from three populations were used to examine patterns of covariation among body size, metabolic rate, and selected reproductive and developmental traits. Mass at birth and at 21 days, growth rates of individual neonates and whole litters, litter size, interlitter interval, and metabolic rates of adult females were used as dependent variables against maternal mass in allometric equations. Litter mass was positively correlated with maternal mass within each of the three populations. Conversely, litter size, litter mass at 21 days, litter growth rate, interlitter interval, and maternal metabolic rate were correlated with maternal mass in only one or two of the populations. Neonatal traits (mean mass of individuals at birth and at weaning and their growth rates) were consistently independent of maternal mass. There was no significant relationship between any of the reproductive parameters measured and metabolic rate of individual females. These results support the view that patterns of covariation in life history traits, metabolic rate, and maternal mass, which are generally evident in interspecific comparisons, are not necessarily apparent at the level of individuals within a single population.