The biogeography of warming tolerance in lizards

Abstract

Aim Many ectotherms are at risk from climate change as temperatures are increasingly exceeding their thermal limits. Many evaluations of the vulnerability of ectotherms to climate change have relied on statistical metrics derived from coarse‐scale climatic data, which may result in misleading predictions. By applying an integrative approach, we investigated geographical correlates of the vulnerability of lizards to climate change. Location Globally. Taxon Lizards. Methods We combined data on lizard thermal physiology and ecology, with high‐resolution climate data and biophysical modelling to assess lizards’ vulnerability to climate change. We calculated warming tolerance (difference between their body temperatures and upper thermal limits) and number of hours of activity. We investigated associations between warming tolerance and activity time with latitude, altitude and biome types. We compared our approach with traditional methods to calculate warming tolerance (using solely macroclimatic data). Results We found no latitudinal trend in the warming tolerance of lizards calculated from body temperature, but there was a weak negative correlation with altitude. We found associations between hours of activity and latitude and altitude. Desert species showed narrower warming tolerance than tropical and temperate species. Desert species and temperate species had reduced hours of activity when compared to tropical species. When warming tolerance was calculated from macroclimatic data, however, it was positively correlated with latitude and altitude, and species from tropical forested biomes showed narrow warming tolerances. Main Conclusions Vulnerability metrics calculated from macroclimatic data can produce divergent outcomes to those observed from fine‐scale climatic data. Our work indicates that the ability of desert and temperate lizard species to cope with heat stress by thermoregulating is more constrained than that of tropical species. Integrative assessments of ectotherms' vulnerability to climate change can highlight species and regions that should be prioritised for conservation management.

Potential effects of future climate change on global reptile distributions and diversity

“…Under future climate change scenarios, the climatic conditions with high species richness were projected to shift to even more extreme (warmer and wetter) conditions (Figure 3). This gives cause for concern, given that tropical forest and desert lizards already live in environmental conditions that are close to their thermal limits (Sinervo et al, 2010) and that desert and temperate lizard species have been found to be less able to regulate their temperature in order to deal with heat stress than tropical species (Anderson et al, 2022). Reptiles cannot regulate their body temperature internally, hence they are strongly dependent on using solar energy captured by the environment to regulate their body temperature (Huey, 1982).…”

Open habitats increase vulnerability of amphibian tadpoles to climate warming across latitude

“…However, such macroscale studies often do not account for microclimate exposures, since microclimate variability can dramatically influence exposure to temperature extremes (González‐del‐Pliego et al, 2020; Riddell et al, 2021). Indeed, macroclimate data can produce inaccurate estimates of warming vulnerability relative to fine‐scale climatic data (Anderson et al, 2022).…”

“…Indeed, macroclimate data can produce inaccurate estimates of warming vulnerability relative to fine-scale climatic data (Anderson et al, 2022).…”

Potential future climate change effects on global reptile distributions and diversity

“…To improve SDMs, future studies should try to consider additional factors, such as biotic interactions (Schleuning et al ., 2020) and the reshuffling of species communities (Voskamp et al ., in prep), which might lead to a change in competitive balance (Ockendon et al ., 2014), altered predator-prey relationships (Harley, 2011) or changes in functional diversity ( Stewart et al, 2022 ) and thus the provision of ecosystem functions and services (Pecl et al ., 2017). While the above factors might improve climate change impact projections in the future, such modelling exercises will never reflect the truth, as a species’ response to climate change will be strongly influenced by behaviour, diel rhythm, thermoregulatory potential and microclimatic conditions (Anderson et al ., 2022). This complexity highlights the need for integrative approaches when investigating species’ responses to climate change (Hof, 2021).…”

“…3). This gives cause for concern given that tropical forest and desert lizards already live in environmental conditions that are close to their thermal limits (Sinervo et al ., 2010), while desert and temperate lizard species have been found to be less able to regulate their temperature in order to deal with heat stress than tropical species (Anderson et al ., 2022). Reptiles cannot regulate their body temperature internally, so are strongly dependent on using solar energy captured by the environment to regulate their body temperature (Huey, 1982).…”