Comparative thermal sensitivity of locomotor performance and vulnerability to global warming of two sympatric Phymaturus lizards from cold environments of Patagonia (Argentina)

CABEZAS-CARTES, FACUNDO; KUBISCH, ERIKA; DURAN, FERNANDO; BORETTO, JORGELINA

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2023

0024-4066

Sister species that live in sympatry provide the possibility to analyze the level of divergence in their ecological, physiological, and life-history traits, and how they can coexist without out-competing each other. We study the thermal sensitivity of locomotor performance in sympatric lizards Phymaturus querque and P. zapalensis from Patagonia, Argentina. We measured morphological traits relevant to locomotor performance, the running speed at different body temperatures, and estimated the critical thermal minimum (CTmin) and maximum (CTmax) at which running performance equals zero. We obtained the maximum speeds, the temperature at which the performance is maximized (optimal temperatures, To), and the temperature range over which an individual performs 50% and 80% of their maximal performance (B50 and B80). Also, we recorded the availability of thermal microenvironments for thermoregulation (operative temperatures) and calculate two indices of vulnerability to global warming. Phymaturus zapalensis and P. querque exhibited differences in most of the morphological traits relevant to locomotor performance. Both species present similar To, CTmin, and CTmax but B50 and B80 were broader in P. zapalensis. At the warmest month, the environmental temperatures are already greater than the physiological optimal temperature, indicating that populations could currently be facing challenges in the context of global warming.