Thermal niche as a mechanism to explain the ability (or inability) of dung beetles (Scarabaeoidea: Scarabaeinae) to exploit disturbed habitats

GIMENEZ GÓMEZ VICTORIA C; ZURITA GUSTAVO ANDRÉS; VERDÚ, JOSÉ R.

Buenos Aires

Simposio; 8TH INTERNATIONAL SYMPOSIUM ON THE ENVIRONMENTAL PHYSIOLOGY OF ECTOTHERMS AND PLANTS; 2019

Universidad de Buenos Aires - CONICET

In terrestrial ecosystems insects face a wide range of temperatures among different habitats and through the day and year; consequently, the thermal niche is one of the major determinants of habitat selection and temporal patterns of species activity. In heterothermic flying insects, the thermal niche is defined by the ability to generate heat (endothermy) and the ability to regulate the internal temperature (thermoregulation). The Atlantic forest of Argentina is one of the most diverse and threatened ecosystems worldwide; previous studies showed that the replacement of the native forest by land uses reduces the diversity of dung beetles (especially in those habitats affecting micro-climatic conditions); however, the mechanism behind these changes have not been explored. In this study, our main objective was explore the role of the thermal niche in dung beetles to explain 1) the ability (or inability) of some native species to exploit human created habitats and 2) the observed reduction on species diversity following forest replacement. On 17 dung beetle species we measured variables associated with the thermal niche (endothermy, thermoregulation and other linked variables) using infrared thermography. From univariate and multivariate analysis, we compared species among disturbed habitats and the native forest according the thermal niche. The results showed that the endothermy was the variable better explaining the capacity of dung beetle species to exploit (or not) human created open habitats. Only diurnal species with very low endothermy were active in open habitats; evening/nocturnal/crepuscular species showed similar and high endothermy in all habitats. In relation to thermoregulation mechanisms, all species (with only one exception) did not showed defined and efficient mechanisms of physiological thermoregulation. In view of the accelerated process of forest replacement and climate change, a more profound understanding of physiological requirement of species is essential to predict and mitigate future extinctions.