Towards predicting responses to an extreme event: traits that influence ground-dwelling beetles' susceptibility to volcanic ash

Extreme events are important determinants of environmental changes at multiple geographical and temporal scales, influencing the ecology and evolution of species. Volcanism in particular can modify entire landscapes through ash deposition, affecting the survival and abundance of susceptible species and favouring tolerant ones. However, there is still a lack of information for predicting which species will be more or less affected by volcanic disturbances. We test the hypothesis that the effect of volcanic ash will differentially affect taxa according to their morphological traits. We used a ground-dwelling beetle community that was sampled before and immediately after the last eruption of the Puyehue-Cordon Caulle (PCC) volcano. We measure traits that might help predicting responses to the ash deposition in insect species susceptible to the PCC volcanic eruption - i.e., their abundance decreased considerably - and compared them to others that were tolerant. We examined cuticle thickness, its structures (i.e., hairs) and microsculptures, and body size. We found that traits associated with smoothness of the cuticle (fewer hairs and microsculptures) and a small body enables species to better tolerate the negative effects of volcanic ash. These results are the first to explicitly test for traits that could help to predict which species will be more tolerant to volcanic ashes, a widespread disturbance associated with volcanism. Extreme events such as volcanism modify entire landscapes (through ash deposition), harming susceptible species and favoring tolerant ones. Predicting which species will be more or less affected by volcanic disturbances provides key information to understand the changes in volcanism-disturbed ecosystems. We compared morphological traits of ground-dwelling beetle species that were sampled before and immediately after the last eruption of a Patagonian volcano. Traits associated with smoothness of the cuticle and a small body enable beetles to better tolerate the volcanic ash.image