MADRID – For the first time, thermal tolerance in relation to body size has been made measurable in cold-blooded animals. Scientists from a Spanish and a Chilean university have been researching the effect of global warming on these animals for almost three years.
In a joint publication in the scientific journal Nature Climate Change, Spanish scientist Ignacio Peralta-Maraver of the University of Granada and Chilean scientist Enrico L. Rezenda of the Pontificia University in Santiago explain how, from a physiological point of view, that cold-blooded animals ( fish, amphibians or reptiles) are slowed in their growth process by abnormalities in the metabolism as a result of higher temperatures.
Cold-blooded animals show large differences in body size, depending on the temperature of their environment. Furthermore, for nearly three years, scientists studied hundreds of scientific articles and museum collections. They took 637 empirical measurements on thermal tolerance and body size in annelids, mollusks, arthropods, fish, amphibians and reptiles.
Cold-blooded animals are getting smaller
With this data, the scientists created an equation that allows them to quantify heat tolerance in the animals studied. As a result, this shows that large and small animals react differently to thermal stress, or heat stress. Small animals can withstand extremely high temperatures better than large animals. However, their chances of survival decrease significantly the longer the exposure to high temperatures. This reduces the differences in tolerance over a longer exposure period. At the same time, this partly explains why cold-blooded animals are getting smaller and smaller as the earth warms further.
Great ecological significance
The results of this study are of great ecological significance as they help to understand how cold-blooded animals will respond to global warming. In addition, they are correcting previous thermal tolerance calculations for natural populations around the world. The scientists warn against an enormous overestimation of the figures of the traditional calculation methods.