Toward a general understanding of thermal performance curves in biology

Temperature profoundly influences biological processes at all scales, from enzyme kinetics to ecosystem-level metabolism. Despite the enormous physiological diversity of life on Earth—from unicellular microbes to plants and animals—there is a remarkable similarity in how individual-level traits (e.g., metabolic rate, locomotion, growth rate) respond to temperature (1–3). These relationships are captured by thermal performance curves (TPCs), which describe how the rate or magnitude of a biological trait varies continuously with temperature (2, 4). TPCs are typically unimodal and left-skewed (Fig. 1), rising in an Arrhenius-like (that is, exponentially) manner with temperature up to an optimum and then declining steeply beyond a critical upper threshold (5, 6). In their new study, Arnoldi et al. (7) provide a strikingly general explanation for this ubiquitous curve shape, showing that the diversity of mechanistic TPC models and empirical data can be unified under a single, mathematically derived “Universal Thermal Performance Curve” (UTPC).