Temperature responses of life-history traits and per capita growth rates in a constant thermal environment. In Focus: Amarasekare, P. & Coutinho, R. M. (2013) The intrinsic growth rate as a predictor of population viability under climate warming. Journal of Animal Ecology, 82, 1240–1253. Metabolic theory predicts that demographic rates can be expressed as a function of environmental temperature. Amarasekare & Coutinho (2013) build a novel matrix model where demographic rates (fertility, mortality, development) vary according to expected rates of climate warming. They challenge recent studies that claim low population viability of tropical species based on rmax estimated from the Euler–Lotka equation, because the latter assumes a constant stage distribution that is unrealistic under fast rates of warming and for organisms with long development. In those cases, the measurement of the temperature responses of life-history traits could be based in niche theory.