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Abstract: Ongoing climate change is a major threat to biodiversity. However, although many species clearly suffer from ongoing climate change, others benefit from it, for example, by showing range expansions. However, which specific features determine a species’ vulnerability to climate change? Phenotypic plasticity, which has been described as the first line of defence against environmental change, may be of utmost importance here. Against this background, we here compare plasticity in stress tolerance in 3 copper butterfly species, which differ arguably in their vulnerability to climate change. Specifically, we investigated heat, cold and desiccation resistance after acclimatization to different temperatures in the adult stage. We demonstrate that acclimation at a higher temperature increased heat but decreased cold tolerance and desiccation resistance. Contrary to our predictions, species did not show pronounced variation in stress resistance, though plastic capacities in temperature stress resistance did vary across species. Overall, our results seemed to reflect population—rather than species‐specific patterns. We conclude that the geographical origin of the populations used should be considered even in comparative studies. However, our results suggest that, in the 3 species studied here, vulnerability to climate change is not in the first place determined by stress resistance in the adult stage. As entomological studies focus all too often on adults only, we argue that more research effort should be dedicated to other developmental stages when trying to understand insect responses to environmental change. [ABSTRACT FROM AUTHOR]

Heat tolerance is a trait of paramount ecological importance and may determine a species' ability to cope with ongoing climate change. Although critical thermal limits have consequently received substantial attention in recent years, their potential variation throughout ontogeny remained largely neglected. We investigate whether such neglect may bias conclusions regarding a species' sensitivity to climate change. Using a tropical butterfly, we found that developmental stages clearly differed in heat tolerance. It was highest in pupae followed by larvae, adults and finally eggs and hatchlings. Strikingly, most of the variation found in thermal tolerance was explained by differences in body mass, which may thus impose a severe constraint on adaptive variation in stress tolerance. Furthermore, temperature acclimation was beneficial by increasing heat knock-down time and therefore immediate survival under heat stress, but it affected reproduction negatively. Extreme temperatures strongly reduced survival and subsequent reproductive success even in our highly plastic model organism, exemplifying the potentially dramatic impact of extreme weather events on biodiversity. We argue that predictions regarding a species' fate under changing environmental conditions should consider variation in thermal tolerance throughout ontogeny, variation in body mass and acclimation responses as important predictors of stress tolerance. [ABSTRACT FROM AUTHOR]

Ongoing climate change and especially the associated heat waves may pose a major challenge to biodiversity conservation. Although many ectotherms in temperate zones may benefit from current climate change, others will suffer. However, the specific biological features determining the response of a given species to climate change have remained largely unknown. In the present study, conducted in three copper butterfly species that likely differ in their vulnerability to climate change, we tested the responses to simulated heat waves using ecologically realistic diurnal temperature cycles. Surprisingly, we found little support for our hypothesis that the most vulnerable species will suffer most from simulated climate change. Although species differed significantly in their responses to treatments, such variation appears to be largely ruled by selection pressures associated with the specific developmental pathway. In general, simulated heat waves had little effect on fitness components including fat content and immune function. Consequently, all three species appear to be capable of dealing with projected changes during their larval and pupal development. Whether this also applies to other developmental stages, more extreme stress or indirect effects climate change remains to be seen. Identifying the critical factors determining the vulnerability of a species to climate change will remain an important task for future research. [ABSTRACT FROM AUTHOR]