A bstract The pace of life hypothesis (POL) suggests that organisms’ life history, physiological and behavioural traits should co-evolve. In this context, glycaemia (i.e., blood glucose levels) and its consequences to ageing through its reaction with proteins and other compounds (i.e. glycation) constitute physiological traits which remain under-investigated in an evolutionary comparative framework, notably in relation to life history traits and ecological factors. Although their blood glucose levels are twice as high as in mammals, birds live longer when accounting for their body mass. We thus performed a comparative analysis on glucose and albumin glycation rates on 87 bird species from 22 orders, in relation to life history traits (body mass, clutch mass, maximum lifespan and developmental time) and diet. Glucose levels correlated positively with albumin glycation rates in a non-linear fashion, suggesting resistance to glycation in species with higher glucose levels. Plasma glucose levels decreased with increasing body mass and increased with maximum lifespan before reaching a plateau. Finally, terrestrial carnivores showed higher albumin glycation compared to omnivores. Our results open an important new avenue of research to help us to better understand the striking condition of hyperglycaemic yet long-lived birds.

Understanding glycaemia and glycation levels in birds: diet and life history traits associations