A study indicates that human activities, such as the introduction of exotic species or the use of pesticides, could aggravate the negative effects produced by the climate on the physiology of these animals.

Specimens of the Tizón lizard, Gallotia galloti, from a town in the south of the island of Tenerife.

A recent study in which the National Museum of Natural Sciences (MNCN-CSIC) participates, belonging to the Higher Council for Scientific Research of Spain, in collaboration with researchers from institutions in Portugal and Slovenia, shows that the stress indices of the populations of lizard Tizon, Gallotia galloti, from Tenerife they increase in locations with more extreme and changing temperatures and less rainfall.

Furthermore, the study, published in the journal Science of the Total Environment, notes that human disturbances such as the introduction of exotic species or the use of pesticides could aggravate the negative effects produced by the climate on the physiology of these animals.

A poorer physical condition and a high concentration of glucocorticoids in the stool and parasites in the blood are some indicators of stress in animals. On the smut lizard on the island of Tenerife, unique Canary species With a fundamental ecological role as a disperser of seeds, the values ​​of these parameters vary between the populations of different localities.

“Our objective in this study was to verify if this variation is related to the climate and human activities“, Says Rodrigo Megía Palma, researcher at the MNCN and the University of Porto. “To do this, we measure the parameters in 611 adult specimens from 24 locations relating them to factors such as the maximum temperature that is reached in the hottest month of summer, the annual fluctuations in temperature, the degree of precipitation and the level of human development in the area ”, explains the researcher.

Males vs females

“The results we obtained show that the factors analyzed influence the indicators of stress and affect males and females unevenly“, Explain Lucía Arregui, researcher at the MNCN. Specifically in females, the levels of infection by parasites were higher in areas of the island with higher temperatures and less rainfall.

“The work suggests that the factor key for females is the Water, a resource that they need in abundance at the end of the reproductive season to produce eggs or recover after laying. However, in males we have found that anthropic pressure explains the variation in the concentration of glucocorticoids in their feces, a situation that could be aggravated during the warmer months ”, Arregui points out.

In addition, both males and females presented a worse body condition in those localities with higher temperature swing, a parameter that varied with altitude throughout the more than 3,700 meters of altitude that are reached on the island. “Our work also suggests that human actions such as introduction of species such as rats or cats or the use of certain pesticides for agricultural activities could aggravate the stress produced by the weather in males ”, Megía highlights.

“The stress indices analyzed, some of them easy to study, such as the parasitic load on the lizard blood, serve as biological indicators of the environmental disturbance in Tenerife, which is relevant as a model to be able to anticipate and manage the impact of climate change on this and possibly other island ecosystems“, He concludes.