Studies of thermoregulation and thermal effects have been one of the most prolific and enduring topics in functional biology for the past century (for reviews, see Hochachka & Somero, 1984; Prosser, 1986; Cossins & Bowler, 1987). The popularity of thermal biology stems from its great significance for biological systems. Temperature has pervasive effects on biological rate processes: rapid changes in body temperature alter nearly all physiological functions by approximately 6–10% per degree Celsius over a broad thermal range. Organismal and population-level traits that depend on those processes, such as energy utilisation, growth and reproduction, are also therefore greatly affected by temperature change. Thus virtually everything that an organism does is influenced by and dependent on its thermal condition.

Despite the major impact of temperature on functional capacities, biological systems have evolved in and adapted to almost every thermal environment on earth. Adult metazoans have successfully colonised environments ranging from –70 °C to 50 °C, while the thermal tolerance of dormant stages and prokaryotes is even greater. Individual organisms and their offspring usually encounter a range of temperatures during their life-cycle, varying from daily cycles to seasonal or longer-term climate change. Responses to a given temperature or temperature change can vary markedly between species and between different life-history stages of the same species. Much of the literature of thermal biology has been concerned with determining thermal tolerances and describing patterns of function at different temperatures.