Adaptive energetics in house mice, Mus musculus domesticus, from the island of Porto Santo (Madeira archipelago, North Atlantic)

Abstract

The bioenergetic strategies of house mice (Mus musculus domesticus) from the island of Porto Santo were investigated and compared with those of mice from mainland Portugal. Energy obtained from food ingestion was 18.2% lower in Porto Santo mice than in mainland mice (1.53 vs. 1.87 kJ/g/day). The same pattern was observed for metabolisable energy intake, which was 19.2% lower in island specimens (0.87 vs. 1.08 kJ/g/day for mainland specimens). Apparent digestibility was similar in both groups of mice. Basal metabolic rate (BMR) of Porto Santo individuals was low (1.16 ml O(2)/g/h), representing only 56% of the predicted value, based on body mass, while mainland individuals exhibited a BMR closer to the expected value, corresponding to 87% of the predicted value (1.80 ml O(2)/g/h). Thermoregulatory abilities within the range of 10-28 degrees C ambient temperature did not differ between island and mainland mice. Results suggest an adaptation of Porto Santo mice to the environmental aridity of the island of Porto Santo, leading to a conservative energetic strategy.