Microclimate buffering and thermal tolerance across elevations in a tropical butterfly.

Gabriela Montejo-Kovacevich,Caroline N Bacquet,Simon H Martin,Joana I Meier,Nicola J Nadeau,Chris D Jiggins,Monica Monllor

doi:10.1242/jeb.220426

Abstract

ABSTRACTMicroclimatic variability in tropical forests plays a key role in shaping species distributions and their ability to cope with environmental change, especially for ectotherms. Nonetheless, currently available climatic datasets lack data from the forest interior and, furthermore, our knowledge of thermal tolerance among tropical ectotherms is limited. We therefore studied natural variation in the microclimate experienced by tropical butterflies in the genus Heliconius across their Andean range in a single year. We found that the forest strongly buffers temperature and humidity in the understorey, especially in the lowlands, where temperatures are more extreme. There were systematic differences between our yearly records and macroclimate databases (WorldClim2), with lower interpolated minimum temperatures and maximum temperatures higher than expected. We then assessed thermal tolerance of 10 Heliconius butterfly species in the wild and found that populations at high elevations had significantly lower heat tolerance than those at lower elevations. However, when we reared populations of the widespread H. erato from high and low elevations in a common-garden environment, the difference in heat tolerance across elevations was reduced, indicating plasticity in this trait. Microclimate buffering is not currently captured in publicly available datasets, but could be crucial for enabling upland shifting of species sensitive to heat such as highland Heliconius. Plasticity in thermal tolerance may alleviate the effects of global warming on some widespread ectotherm species, but more research is needed to understand the long-term consequences of plasticity on populations and species.

Highlights

Land use and climate change are forcing organisms in the Anthropocene to move, adapt or die (Dirzo et al, 2014)
Despite tropical ectotherms making up half of the animal species described, our knowledge of their potential to cope with high temperatures in natural settings is limited, especially along elevational clines (García-Robledo et al, 2016; Sheldon, 2019)
We found that tropical forests have great climatic buffering potential, especially at lower elevations, and that this was similar across two independent elevational clines on both sides of the Ecuadorian

Summary

Introduction

Land use and climate change are forcing organisms in the Anthropocene to move, adapt or die (Dirzo et al, 2014). Moving in an increasingly fragmented landscape or adapting to an ever-changing climate might be difficult for organisms usually. Despite tropical ectotherms making up half of the animal species described, our knowledge of their potential to cope with high temperatures in natural settings is limited, especially along elevational clines (García-Robledo et al, 2016; Sheldon, 2019). We need a better understanding of the ability of ectotherms to cope with temperatures across elevations and of the climate buffering potential of tropical forests (García-Robledo et al, 2016; Sheldon, 2019)

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Conclusion