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 °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.