Assessing the capacity of endemic alpine water beetles to face climate change

Abstract

1. Accurate assessments of species’vulnerability to climate change requireintegrated measurements of its different drivers, including extrinsic (the magnitude andrate of climate change) and intrinsic factors (organisms’sensitivity and adaptive capac-ity). According to these factors, aquatic insects restricted to alpine ponds may be espe-cially threatened by climate change. However, vulnerability predictions based on suchan integrative approach are scarce for alpine pond taxa. 2. We combined distributional, climatic data and experimental measurements of heattolerance and acclimation capacity of two water beetles endemic to Sierra NevadaNational Park (Spain) to evaluate different components of their vulnerability to climatechange. We estimated: (i) changes in climatically suitable habitat under different scenar-ios of climate change and (ii) thermal safety margins (the difference between speciesupper thermal limits and the maximum temperatures in their current localities), for cur-rent and future conditions, and acclimation capacity, as measures of the physiologicalcapacity to persistin situ. 3. Species distribution models predicted a virtual loss of climatically suitable areaunder different climate change scenarios. Nonetheless, both taxa showed heat tolerancelimits above the predicted maximum temperatures in their current localities (but nocapacity to adjust such limits through acclimation). Therefore, these beetles could havethe physiological capacity to deal with warming conditionsin situ. 4. We recommend concentrating conservation efforts in current localities as the mostefficient management strategy for both taxa. Our results stress the importance of account-ing for physiological tolerances when predicting the vulnerability to climate change inalpine freshwater biota.