RESTING METABOLIC-RATE AND REPRODUCTION IN THE INSECTIVORA

This paper investigates the relationship between body mass, resting me tabolic rate (RMR) and life history in the insectivore families Tenrec idae and Soricidae, RMR and a number of life history variables scale t o body mass within both families. Residuals from least squares regress ion analysis produced relative or mass-independent values which were u sed to determine the relationship between RMR and reproduction. Within the Tenrecidae, RMR was not correlated with any of eight reproductive variables when the effect of mass was removed, The failure of species in this family to gain a reproductive advantage from elevated RMR may be due to phylogenetic constraints on reproduction, Species with elev ated RMR may benefit from improved homeothermy rather than increased r eproductive output, In the Soricidae, an increase in relative RMR was associated with a decrease in gestation length, an increase in specifi c foetal growth velocity and an increase in litter size, The possibili ty that energetic and reproductive strategies in the Soricidae may hav e evolved under separate constraints is discussed, It is concluded tha t RMR is sometimes associated with life histories in the Insectivora, but its effect varies significantly between families.