The dark side of climate change

The fact that the caves are semi-closed systems with an almost constant temperature makes them almost ideal sites where to study where to study the effects of the ongoing global warming on biological communities. In spite of that, the underlying mechanisms behind the response of specialized subterranean species to global warming are still largely undiscussed. By means of two years observations data, we characterize the thermic conditions of 33 caves in the Western Alps, and relate the hypogean microclimate to the occurrence of subterranean-adapted Troglohyphantes spiders. Regression analysis points out a specific response to temperature as well as a significant effect of the past Pleistocene glaciations on their present distribution. In a second step, we investigate the relationship between temperatures recorded in monitored caves and the corresponding external temperature. We emphasize the mechanisms for which the constant temperature recorded inside corresponds in good approximation to the mean value of the annual temperature outside and use this direct relation to extend the results to a wider dataset, including records from over 350 caves in the Western Italian Alps. Specifically, we employ Ecological Niche Modeling techniques to predict habitat suitability both in the Last Glacial Maximum and in future global warming scenarios. In light of IPCC’s projections of global average temperature increases, we assess the general sensitiveness of our model species to future increase of temperature, pointing out a future decline for hypogean adapted species.