Climate Change and Lizards: Reproduction Strategy May Need to Change, Researchers Say

In an attempt to adjust to increasing climate temperatures, common lizards may start breeding more frequently but also start dying off at a younger age. To better understand retilian response to climate change, an international team of researchers closely examined how a warmer climate of just two-degrees celsius would affect populations of common lizards (Zootoca vivipara) over time. Since a reptile's body temperature depends directly on the atmospheric temperature, researchers predict that lizards will not be able to cope with future climate change estimates. As a result, they believe many common lizards could disappear by the year 2100, according to a news release.

For their study, researchers used a Metatron, which is a system of semi-natural enclosures that allowed them to manipulate temperatures. They created two distinct climates: one similar to present day temperatures and one two-degreesv (celsius) warmer, which certain climate change models predicted for the end of the century. Throughout the course of two years, researchers tested 18 populations of common lizards under both climatic situations, taking not of growth, reproduction and survival rates and concluded that an increased adult mortality would ultimately lead to decreased population rates. Within 20 years, this would cause rapid population extinctions. 

"While a two-degrees warmer climate might seem beneficial at first, as it leads to faster growth of juvenile lizards and earlier access to reproduction, it also leads to lower survival in adult individuals, which should endanger population survival," Elvire Bestion, co-lead author of the study from the University of Exeter, explained in the release.

Common lizards are very unique species, in that they give birth to live young, unlike other lizards who lay eggs, and they live farther north than any other reptile species. Generally, common lizards are found throughout areas of Europe and northern Asia. They can also be seen sporting brown, red, grey, green, or black-colored scaly skin.

"Anecdotally, we also showed that warmer climates led some adult females to engage into a second reproduction event during the summer, while these lizards normally reproduce only once a year during the spring. Combined with the earlier juvenile reproduction and the higher adult survival, these results suggest a shift of demographic strategy from a relatively long life and low reproductive output to a faster life, higher reproductive investment. We can wonder whether this strategy shift may help adaptation of populations to warmer climates over time," Bestion added. 

The study was recently published in the journal PLOS Biology.

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