MICE, VOLES AND HAMSTERS - METABOLIC RATES AND ADAPTIVE STRATEGIES IN MUROID RODENTS

The hypothesis that the metabolic rates of mammals are convergent and depend on functional adaptations was tested against the claim that taxonomic affiliations sufficiently account for variations in metabolism. Basal metabolic rates (BMR) of 90 species of muroid rodents (Rodentia, Muroidea) were collected from literature and compared with data on their life history traits: food habits, climate, habitat and biotope. Using clustering procedures and factor analysis three typical strategies were delimited: ''mouse'', ''hamster'' and ''vole''. The last one is related to low-quality food; the other two include selective omnivores, with ''mice'' preferring rich and moist habitats and ''hamsters'' dwelling in arid steppes and deserts. These groups are only partly congruent with the Muridae, Cricetidae and Arvicolidae families. All groups demonstrate similar dependence of BMR on body weight, but ''voles'' and ''mice'' have a significantly higher BMR than ''hamsters''. In contrast, Cricetidae and Muridae have significantly lower BMR than Arvicolidae (ANCOVA). Analysis of residuals within ANCOVA for groups and for families corroborates this. Both factors, taxonomic affiliation and functional adaptations, independently exert similar effects upon the value of BMR in muroid rodents.