The complex drivers of thermal acclimation and breadth in ectotherms

Abstract

Thermal acclimation capacity, the degree to which organisms can alter their optimal performance temperature and critical thermal limits with changing temperatures, reflects their ability to respond to temperature variability and thus might be important for coping with global climate change. Here, we combine simulation modelling with analysis of published data on thermal acclimation and breadth (range of temperatures over which organisms perform well) to develop a framework for predicting thermal plasticity across taxa, latitudes, body sizes, traits, habitats and methodological factors. Our synthesis includes > 2000 measures of acclimation capacities from > 500 species of ectotherms spanning fungi, invertebrates, and vertebrates from freshwater, marine and terrestrial habitats. We find that body size, latitude, and methodological factors often interact to shape acclimation responses and that acclimation rate scales negatively with body size, contributing to a general negative association between body size and thermal breadth across species. Additionally, we reveal that acclimation capacity increases with body size, increases with latitude (to mid-latitudinal zones) and seasonality for smaller but not larger organisms, decreases with thermal safety margin (upper lethal temperature minus maximum environmental temperatures), and is regularly underestimated because of experimental artefacts. We then demonstrate that our framework can predict the contribution of acclimation plasticity to the IUCN threat status of amphibians globally, suggesting that phenotypic plasticity is already buffering some species from climate change.

Different metrics of thermal acclimation yield similar effects of latitude, acclimation duration, and body mass on acclimation capacities

“…Thus, regardless of whether the Einum et al () or Seebacher et al () metrics of thermal acclimation are used, body mass interacts with latitude and acclimation duration, and more often than not acclimation strength is positively associated with body size. Importantly, all of these results are consistent with patterns in the other datasets we analyzed (Rohr et al, ).…”

Pathogen exposure disrupts an organism's ability to cope with thermal stress

“…As ramping rates slowed, however, both upper thermal limits generally and the magnitude of the difference between infected and uninfected animals gradually declined (e.g. Figure ), most likely because prolonged exposure to thermal stress caused an accumulation of physiological damage (Jørgensen et al, ; Rezende et al, ; Rohr et al, ). Both observations are consistent with previous work investigating the effects of slow rates of temperature change on survival of ectotherms (Kingsolver & Buckley, ; Rezende et al, ).…”

Heat tolerance and acclimation capacity in subterranean arthropods living under common and stable thermal conditions

“…These questions remain poorly explored in other extremely thermally stable habitats, such as subterranean environments, although some recent studies have found support for the climatic variability hypotheses for cave springtails (Raschmanová, Šustr, Kováč, Parimuchová, & Devetter, ) and spiders (Mammola, Piano, Malard, Vernon, & Isaia, ). However, the generality of such patterns remains controversial (see Gunderson & Stillman, ; Rohr et al, ), as other studies have found weak support for a correlation between some thermal tolerance traits and the magnitude or predictability of thermal variability (e.g., Kellermann et al, ; Overgaard, Kearney, & Hoffmann, ; Seebacher, White, & Franklin, ).…”