Abstract

We measured basal metabolic rate, thermal conductance, body temperature, and temperature differential of three populations of the Sigmodontine-rodent Abrothrix andinus in three different habitats of the Andean range of northern Chile. Individuals from the three habitats were good thermoregulators, were capable of maintaining a high mass-independent temperature differential, and were able to survive the cold ambient temperatures during the night. We compared our data with previously published information on seasonal energetics of another population of A. andinus in the Andean range of central Chile and with species of the genus Abrothrix in a Mediterranean climate. Energetics of Abrothrix did not vary in response to different climatic conditions, which favored the hypothesis that it was a fixed character probably reflecting a common ancestor of Andean origin or radiation along the Andes Mountains.