Climate change undoubtedly affects all organisms but researchers have found that reptiles are particularly vulnerable as their body temperature is directly affected by temperature in the environment.

In a study published in the journal PLOS Biology, researchers examined what would happen to a populations of common lizards (Zootoca vivipara) should the climate warm by 2 degrees Celsius, the predicted world temperature by the end of the century. According to the results of their research, Elvire Bestion and colleagues were able to show that many of the common lizard populations will disappear quickly if warmer temperatures persist.

To study the lizards, the researchers used a Metatron, a system of semi-natural enclosures that allowed for temperature manipulation, creating two distinct climates: one simulating present conditions and the other warmer by 2 degrees Celsius. There were 18 common lizard populations utilized in the study, each one placed in either a "present" or "warmed" enclosure for more than two years. The populations were then surveyed for another year, allowing the researchers to observe how warmer climates had an impact on the lizards in terms of demographic parameters like survival, reproduction and growth rate.

Bestion said the warmer climate was actually beneficial to the lizards at first as it led to earlier access to reproduction (some adult females also engaged in second reproduction event in a year when they typically only have one annually) and faster growth rates in juveniles but it led to lower survival in the adults of the species.

"A model of population dynamics showed that the increased adult mortality would lead to decreased population growth rates, and ultimately rapid population extinctions in around 20 years," she added.

While the results of the study appear dramatic, it does not predict that common lizards will become extinct at the level of the species, clarified Julien Cote, the study's co-lead author. However, it is suggested that common lizard populations at the southern end of the species' distribution range should be tracked specifically as they will be the likeliest to suffer from the effects of a warmer climate.

Depending on carbon emission scenarios, the study showed that 14 to 30 percent of common lizard populations in Europe will be threatened by a warming climate.

The study received funding support from "TULIP," a French Laboratory of Excellence project.

Photo: Tero Laakso | Flickr

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