Metabolism and thermoregulation in rodents: are these adaptations to habitat and food quality?

Low minimal resting metabolic rates, 20-50% less than predicted for body mass, were recorded for 12 of 15 rodent species from different habitats and taxonomic groups. In 7 of the 15 species thermal conductance was higher than predicted for body mass; in 6 it was either lower or as predicted. Analysis segregated the animals into groups suited to arid, mesic and subterranean habitats on the basis of metabolism and thermoregulation in 11 of the 15 species. The adaptations of Praomys natalensis, a mesic species which can be grouped with the arid area kind, in contrast to Gerbillus allenbyi, Otomys irroratus and Lemniscomys griselda, are also examined. Low metabolic rates in species from arid areas are probably an adaptation to extend longevity, essential in an environment where reproduction does not happen every year. -from Author