Hypogean carabid beetles as indicators of global warming?

Climate change has been shown to impact the geographical and altitudinal distribution ofanimals and plants, and to especially affect range-restricted polar and mountaintop species.However, little is known about the impact on the relict lineages of cave animals. Groundbeetles (carabids) show a wide variety of evolutionary pathways, from soil-surface (epigean)predatory habits to life in caves and in other subterranean (hypogean) compartments. Wereconstructed an unprecedented set of species/time accumulation curves of the largest carabidgenera in Europe, selected by their degree of ‘underground’ adaptation, from true epigeanpredators to eyeless highly specialized hypogean beetles. The data show that in recent periodsan unexpectedly large number of new cave species were found lying in well establishedEuropean hotspots; the first peak of new species, especially in the most evolved undergroundtaxa, occurred in the 1920–30s and a second burst after the 70s. Temperature data show largewarming rates in both periods, suggesting that the temperature increase in the past centurymight have induced cave species to expand their habitats into large well-aired cavities andsuperficial underground compartments, where they can be easily sampled. An alternativehypothesis, based on increased sampling intensity, is less supported by available datasets.