The absence of water in the environment affects the thermal tolerance of lizards more than the lack of food, according to a new study.

An adult male rock lizard in the Peñagolosa Massif (Castellón).

The Iberian lizards They are reptiles very threatened by the decrease in the populations of insects on which they feed and by the increase in temperatures due to global warming.

A study led by researchers from the National Museum of Natural Sciences (MNCN-CSIC) shows that the absence of Water to drink reduces the maximum temperature that these animals can tolerate. Therefore, the forecast of less rainfall and more drought in the future threatens to undermine its ability to cope with the climate crisis.

“Body temperature and the amount of water stored in our tissues are closely related. To regulate body temperature, any animal makes decisions based on the water availability, for example, looking for a shade if we can’t hydrate ourselves ”, he explains Salvador Herrando, researcher at the MNCN and the University of Adelaide, Australia.

“Taking this into account, in this study we asked whether the maximum temperature that Iberian lizards can tolerate changes depending on the availability of water in the environment,” says the researcher.

Lizard experiments

For the experiment they studied populations of rock lizard (Podarcis muralis), adapted to humid environments in Castellón and Huesca; Y red-tailed lizard (Acanthodactylus erythrurus), adapted to dry media in Valencia and Madrid.

“In the laboratory, we measured the maximum temperature that these species tolerated if they could eat and drink, or if they only ate,” he says. David Vieites, also a researcher at the MNCN.

“For both species we observe that, when they only have food, a population tolerated 3 to 4 ºC more than the other, twice that in conditions in which there is both water and food. This implies that, in the absence of water, some populations are less adapted to withstand high temperatures than others. Less thermal tolerance implies a greater risk of extinction in the face of global warming ”, Herrando points out.

“Reviewing the ecological studies published to date, we also show that the effects of air temperature on thermal tolerance have been studied five times more than the effects of water in terrestrial animals. Therefore, our results recommend a greater effort to investigate the repercussions of availability of drinking water on how biodiversity responds to climate change ”, concludes Vieites.