Ecological and evolutionary drivers of thermal performance curves across the tree of life
Biological rates typically follow a unimodal thermal performance curve (TPC), yet the ecological and evolutionary drivers shaping TPC variation remain poorly understood. We compiled an extensive thermal response database covering 896 TPCs for 416 species and 60 traits, spanning microbes to multicellular organisms. Our analyses reveal three key insights. First, environmental seasonality strongly structures TPCs: species in stable environments exhibit narrower thermal ranges and greater asymmetry, with environmental temperature outperforming latitude as a predictor. Second, trait type and organismal complexity modulate thermal sensitivity: emergent traits have narrower ranges than physiological traits, and complex organisms display reduced heat tolerance. Third, prokaryotes and eukaryotes differ fundamentally: while prokaryotes shift thermal limits symmetrically, eukaryotes show constrained upper limits relative to cold tolerance. These findings highlight how environmental stability, trait organization, and evolutionary history shape species thermal niches, providing crucial insights into vulnerability and adaptation under climate change.