Thermal tolerance and vulnerability to climate change in subterranean species: a case study using an Iberian endemic pseudoscorpion

Scientists are renewing their efforts to predict the impact of climate change on biodiversity. Subterranean environments represent ideal systems to study the effect of global change in species with poor dispersal capabilities. We assess the vulnerability to climate change of the subterranean pseudoscorpion Neobisium (Blothrus) vasconicum vasconicum (Nonidez, 1925) (Neobisiidae). Thermal tolerance was measured using two complementary estimates of upper thermal limits: (i) from thermal conditions of the localities in which the species occurs (realised upper thermal limit, RUTL), and (ii) from experimentally determined thermal tolerance data (physiological upper thermal limit, PhUTL). Then, thermal safety margins (TSM) were calculated for all known localities for current and future climatic conditions, using the thermal limits from both approaches. The physiological thermal limit (PhUTL = 17.57 degrees C) was 3.27 degrees C higher than that obtained from the distributional and climate data (i.e., the hottest cave in which the species occurs; RUTL = 14.3 degrees C). Regarding TSM, the future temperature (2070; RCP 8.5) of a half of the caves will be higher than the RUTL and in none of them, it would exceed the average PhUTL. This indicates that the species could have some physiological capacity to cope with warming temperatures in situ. We hypothesize that the most realistic upper thermal limit of the species could be between the RUTL and PhUTL. This study shows that complementary approaches to estimate thermal tolerance could provide more accurate predictions of the capacity to face climate change, not only in subterranean species, but also in poor dispersal species.