Thermotolerance at three temperatures of high Andean limnic tardigrades

Tardigrades, a phylum of microscopic organisms well known for their resistance to extreme conditions thanks to adaptations such as cryptobiosis, in which they are able to suspend their metabolism until more favorable conditions arise. These organisms are found in a wide range of environments, and high Andean mountains are not the exception, even though weather conditions are highly variable during the day, let alone a month. An experiment was thus conducted in Bogotá, Colombia at the campus of the National University of Colombia to evaluate the resistance of limnic tardigrades found on trees, three sets of fifteen tardigrades were exposed to 20°C, 30°C and 40°C , at a rate of 0,5°C/min, which were then examined to determine the number of alive, dead or in “tun” organisms. The results for the tardigrades exposed at 20°C were 4 dead in the first set and 3 dead in the second and third set; at 30°C, 6 dead in the first set and 5 dead in the second and third set; at 40°C, 6 dead in the first set, 7 dead in the second set and 8 dead in the third set. Succinctly, 22,22% were dead at 20°C; 35,56% were dead at 30°C and 46,67% were dead at 40°C. No tardigrades were found in “tun” state at any temperature. Therefore, the data shows an increase in mortality as the temperature rises, even so, taking into account the climatic conditions registered, studied tardigrades are able to withstand higher temperatures than what they are exposed to usually, moreover Andean tardigrades do not show phenotypic plasticity or adaptation. As for the lack of “tun” state it implies that high temperatures, at least at this rate, do not trigger this state while conditions like desiccation do, more research is needed on this account.