Mammalian metabolism, longevity and parasite species richness

Basal metabolic rate (BMR) scales allometrically with body mass in mammals, but the reasons why some species have higher or lower metabolic rates than predicted from their body mass remain unclear. We tested the idea that par asite species richness may be a contributory factor by performing a compara tive analysis on 23 species of mammals for which data were available on par asite species richness, BMR, body mass and two potentially confounding vari ables, i.e. host density and host longevity. Parasite species richness was positively correlated with BMR and negatively correlated with host longevit y independent of body mass.