Search

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]

Climate change poses a significant challenge to all natural systems on Earth. Especially increases in extreme weather events such as heat waves have the potential to strongly affect biodiversity, though their effects are poorly understood because of a lack of empirical data. Therefore, we here explore the sensitivity of a tropical ectotherm, which are in general believed to have a low warming tolerance, to experimentally simulated climate change using ecologically realistic diurnal temperature cycles. Increasing the mean temperature permanently by 3°C had mostly minor effects on developmental traits in the butterfly Bicyclus anynana. Simulated heat waves (strongly elevated temperatures for some time though retaining the same overall temperature mean), in contrast, caused strong negative effects by prolonging development time (by up to 10%) and reducing body mass (-21%), especially when combined with reduced relative humidity. Detrimental effects were carried over into the adult stage, diminishing subsequent performance. Most strikingly, higher temperatures suppressed adult immune function (haemocytes: -54%, lysozyme activity: -32%), which may potentially change the way species interact with antagonists. Heat waves thus reduced fitness parameters by 10-25% for development time and body mass and by up to 54% for immune parameters even in this plastic and widespread butterfly, exemplifying the potentially dramatic impact of extreme weather events on biodiversity. [ABSTRACT FROM AUTHOR]