How butterflies keep their cool: Physical and ecological traits influence thermoregulatory ability and population trends

Abstract

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Hot and bothered: The role of behaviour and microclimates in buffering species from rising temperatures

“…British butterflies have also been well studied over several decades (Brereton et al, 2019;Mason et al, 2015), from which we have a good understanding of their distribution, population trends, functional traits and typical thermoregulatory behaviours. As butterflies are small and ectothermic, their external, thoracic body temperature has been found to be a reasonable proxy for internal body temperature (Casey, 1976;Knapp & Casey, 1986) (Bladon et al, 2020). These findings make a lot of sense.…”

“…Without measuring individual thermoregulatory behaviours in situ, we also cannot compare the use nor efficacy of different mechanisms within and between species, and this makes it challenging to assess whether thermoregulatory behaviours correlate with population trends over the time-scale of recent climate change. Bladon et al (2020) elegantly overcome the shortfalls of previous studies, and with a refreshingly simple approach. Butterflies in the UK are an excellent model group for studying ecological responses to climate change because populations at species' range limits are likely to be frequently exposed to unfavourable climatic conditions (Lancaster, 2016).…”

“…The study underscores the importance of individual thermoregulatory behaviours for understanding species' vulnerability to climate change. In combination with much improved methods for measuring and modelling climate at biologically relevant scales, the approach of Bladon et al (2020) can and should be extended to identify the places and species most at risk, and the steps that conservation practitioners can take to maximise resilience to climate change. Much attention has been given to improving habitat connectivity to facilitate range shifts, but we should also consider how microclimate availability can be enhanced to allow species to manage when they cannot move.…”

“…What, then, is the impact of interspecific variation in buffering ability on the fate of British butterflies under climate change? Over the last 40 years, Bladon et al (2020) found that species capable of behaviourally responding via adjustments to body positioning fared better than those that were largely limited to microclimate selection. This is a significant finding.…”

“…First, it is rare that populationlevel declines under climate change are linked to processes occurring at the level of the individual (Bramer et al, 2018;Buckley et al, 2011;Nowakowski et al, 2018). Second, Bladon et al (2020) demonstrate that not all species have the innate capacity to ef- Globally, we need to better characterise species vulnerability to climate change (Pacifici et al, 2018;Williams et al, 2008). We are in an era of unprecedented ability to measure and model climate at the most biologically relevant spatial and temporal scales (Bennie et al, 2014;Bütikofer et al, 2020;.…”