The CAVEheAT project

What would you do if you lived deep in an isolated cave which has remained at the same temperature for millions of years and you were not able to escape or take shelter in case the cave started to warm up? This may sound like the introduction of one of those “escape room” games so fashionable today, but it actually describes the situation of the inhabitants of deep subterranean environments. The species in these ecosystems cannot accommodate to changing conditions by behavioural plasticity, dispersal or microhabitat use so their only possibility to cope with climate change is to persist in situ. But, to what extent are they ready for such challenge?

The particularities of deep subterranean environments make them ideal models for predicting how species will respond to climate change minimizing the uncertainties typically associated to such predictions. These ecosystems are one of the few in nature whose environmental conditions are as homogeneous as could be obtained in a laboratory. Most highly specialized cave species have a well-defined and narrow distribution range, as they show low mobility. In addition, environmental conditions are practically homogeneous across all microhabitats within a cave system, so small-scale spatial heterogeneity and the possibility of behavioural adjustments are minimal. Such conditions overcome the main limitations of predictive models to assess species vulnerability to climate change.

The CAVEheAT project focusses on the deep subterranean environment to test several hypotheses based on the exciting results obtained in previous studies [1 and 2], in which we did not find differences between thermal tolerances of different subterranean beetles living under different environmental conditions, suggesting a lack of evolutionary adjustment to ambient temperature for these species. Cave species might have lost some of the physiological mechanisms related to thermal tolerance due to the likely high metabolic cost of such mechanisms in a stable environment but with severe resource restrictions. However, the questions that remain are: to what extent this surprising narrow and homogeneous thermal niche is common for the whole subterranean biodiversity? and how this issue could determine the fate of subterranean biodiversity in the face of climate change?

In this project, we are testing for the generality of these interesting previous findings by studying the thermal niche (species acclimation abilities and thermal tolerances) of different lineages of cave beetles with different degrees of specialization to subterranean environments and from different geographical areas (Pyrenees and Cantabrian Mountains).