Extended Data Fig. 10: Relationship across species between thermal tolerance of species measured in laboratory studies and predicted from the Metabolic Index.
Critical thermal maxima (CTmax), reported in previous studies, were measured at the onset of loss of physiological function in a resting state. The ATmax are predicted from the Metabolic Index, as the temperature at which the O2 threshold for metabolic rate in either resting state (Pcrit) or under sustained activity levels (Pcrit × Φcrit), reaches the mean atmospheric O2 pressure, Patm (see Methods, equation (10)). The extrapolation of Pcrit curves to the atmospheric pressure is based on n = 3 independent estimates of the linear increase in Eo with temperature (see Methods). Points for each species are the mean, and error bars show the range among the resulting n = 3 estimates of ATmax. Data are shown for all species in Fig. 5, for which all parameters are available (n = 7). For four out of seven species, the ATmax is reached before the CTmax, even in a resting state. For all seven species, the active ATmax is reached at a lower temperature than the CTmax, and is comparable to the maximum temperature that the species inhabits at atmospheric pressure.
