Basal blood glucose concentration in free-living striped mice is influenced by food availability, ambient temperature and social tactic

International audienceVertebrates obtain most of their energy through food, which they store mainlyas body fat or glycogen, with glucose being the main energy source circulatingin the blood. Basal blood glucose concentration (bBGC) is expected to remainin a narrow homeostatic range. We studied the extent to which bBGC in freelivingAfrican striped mice (Rhabdomys pumilio) is influenced by ecologicalfactors with a bearing on energy regulation, i.e. food availability, abioticenvironmental variation and social tactic. Striped mice typically formextended family groups that huddle together at night, reducing energeticcosts of thermoregulation, but solitary individuals also occur in the population.We analysed 2827 blood samples from 1008 individuals of sevendifferent social categories that experienced considerable variation in foodsupply and abiotic condition. Blood samples were taken from mice in themorning after the overnight fast and before foraging. bBGC increased significantlywith food plant abundance and decreased significantly with minimumdaily ambient temperature. Solitary striped mice had significantly higherbBGC than group-living striped mice. Our results suggest that adaptiveresponses of bBGC occur and we found large natural variation, indicatingthat bBGC spans a far greater homeostatic range than previously thought