Disentangling drivers of thermal physiology: Community‐wide cold shock recovery of butterflies under natural conditions

Abstract

Physiological strategies of terrestrial ectotherms are a delicate interplay between species’ traits and their physical environment. Several theories and overarching hypotheses seek to explain strategies related to thermal physiology with respect to organisms and their environments. However, most of these have been investigated under controlled laboratory conditions with lab‐reared or otherwise acclimated individuals, removing the effect of environmental acclimation. This study examines an in‐situ physiological trait, cold shock recovery, across butterfly communities of the Colombian Andes from different environments, elevations, and ambient conditions. We explored four non‐mutually exclusive hypotheses—1) intrinsic (species) traits dictate response hypothesis; 2) extrinsic (environmental) traits dictate response hypothesis; 3) climate variability hypothesis; 4) thermal melanism hypothesis—to explain cold shock recovery of wild‐caught butterflies from high (1800 m.a.s.l) and low (600 m.a.s.l.) elevations in two habitat types (open and closed canopy). Cold shock recovery was measured as the time following a cold shock to full recovery, that is, flight. Ambient conditions and the thermal melanism hypothesis, which posits an interaction between pigmentation and solar intensity, best explained cold‐shock recovery. Higher temperatures and light exposure reduced recovery time. Dark butterflies under high solar intensity recovered from cold shock faster than light butterflies or those under low solar intensity regardless of species identity, morphology, or habitat characteristics. These results highlight the importance of ambient conditions and the interaction between pigmentation of tropical ectotherms and their physical thermal environments, patterns that may render populations vulnerable to the thermal impacts of climate change and development. Abstract in Spanish is available with online material.

Tropical butterflies use thermal buffering and thermal tolerance as alternative strategies to cope with temperature increase

“…Darker butterflies had stronger thermal buffering abilities than paler butterflies, and darker butterfly species also could tolerate higher temperatures than paler butterflies. This is in‐line with previous evidence that dark butterflies heat up and cool down faster than pale butterflies at a given level of solar radiation (Watt, 1968 ), and achieve higher body temperatures than pale individuals (Dufour et al, 2018 ; Khazan et al, 2022 ). This is also in line with comparative studies across temperate latitudes (Zeuss et al, 2014 ), which found a higher incidence of darker species in cooler conditions, possibly also related to the advantage of darker species in being able to warm themselves in cooler conditions.…”

Tropical butterflies use thermal buffering and thermal tolerance as alternative strategies to cope with temperature increase

“…Darker butterflies had stronger thermal buffering abilities and could tolerate higher temperatures than paler species. This is in-line with previous evidence that dark butterflies heat up and cool down faster than pale butterflies at a given level of solar radiation (Watt 1968), and achieve higher body temperatures than pale individuals (Dufour et al 2018;Khazan et al 2022). This is also in line with comparative temperate studies across latitudes (Zeuss et al 2014), which found a higher incidence of darker species in cooler conditions, possibly also related to the advantage of dark species in being able to warm in cooler conditions.…”