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

Accurate assessments of species' vulnerability to climate change require integrated measurements of its different drivers, including extrinsic (the magnitude and rate of climate change) and intrinsic factors (organisms' sensitivity and adaptive capacity). According to these factors, aquatic insects restricted to alpine ponds may be especially threatened by climate change. However, vulnerability predictions based on such an integrative approach are scarce for alpine pond taxa. We combined distributional, climatic data and experimental measurements of heat tolerance and acclimation capacity of two water beetles endemic to Sierra Nevada National Park (Spain) to evaluate different components of their vulnerability to climate change. We estimated: (i) changes in climatically suitable habitat under different scenarios of climate change and (ii) thermal safety margins (the difference between species upper thermal limits and the maximum temperatures in their current localities), for current and future conditions, and acclimation capacity, as measures of the physiological capacity to persist in situ. Species distribution models predicted a virtual loss of climatically suitable area under different climate change scenarios. Nonetheless, both taxa showed heat tolerance limits above the predicted maximum temperatures in their current localities (but no capacity to adjust such limits through acclimation). Therefore, these beetles could have the physiological capacity to deal with warming conditions in situ. We recommend concentrating conservation efforts in current localities as the most efficient management strategy for both taxa. Our results stress the importance of accounting for physiological tolerances when predicting the vulnerability to climate change in alpine freshwater biota.