Short communication: Evidence for the 'rate-of-living' hypothesis between mammals and lizards not in birds, with field metabolic rate.

Abstract Longevity, an important life-history trait, is determined by extrinsic, intrinsic, or both factors causing mortality. Here, we used body mass (BM), field metabolic rate (FMR), longevity, and female maturity data reported from 300 amniote species to test whether 1) longevity was related to BM, FMR and female maturity, and 2) FMR, female maturity, or both, had a direct effect on longevity and whether an indirect effect of FMR on female maturity improved model fit. The results showed that BM was positively related to longevity and FMR, but negatively related to mass-specific FMR (mFMR) in amniotes. In the best model, phylogenetic path analysis showed that longevity had a direct negatively correlation with mFMR in lizards, and longevity had an indirect negatively correlation with mFMR through female maturity in mammals. However, longevity had a direct positively correlation with mFMR in birds. Furthermore, longevity had a positive correlation associating longevity with female maturity in endotherms (birds and mammals) but only a weak correlation with female maturity in ectotherms (lizards). Our results supported the life-history theory and the ‘rate-of-living’ hypothesis in lizards and mammals but did not support them in birds.