European lizards may 'disappear' in warming world

Lizards may disappear from parts of Europe over the next century, as global warming disrupts their life cycle and breeding habits, researchers said Monday.

While all lizards are not expected to vanish, as many as 30 percent of the current population could be lost, particularly in the southern ranges of their territory, said the study in the journal PLOS Biology.

"Although these results might seem dramatic, we do not predict extinction of common lizards at the scale of the species, but we suggest that populations at the southern edge of their range of distribution might particularly suffer from warmer climates", said co-author Julien Cote, biologist at France's Laboratoire Evolution et Diversite Biologique.

Scientists studied how lizards (Zootoca vivipara) coped for one year in an enclosed space that was two degrees Celsius higher than current temperatures, about the amount of warming expected for the Earth in the next 100 years.

The warmer climate led to faster growth among the juvenile lizards, and an earlier than normal start to breeding.

However, it also was associated with earlier death among the adult lizards, "which should endanger population survival," said co-author Elvire Bestion, an associate research fellow at Britain's Exeter University.

By modeling the effect of these dynamics on the existing lizard population, researchers predicted "that the increased adult mortality would lead to decreased population growth rates, and ultimately to rapid population extinctions in around 20 years," said the study.

However, it remains unclear how the species would adapt under real-life conditions.

Researchers noted that they observed adult females in the warmer climate group adding a second "reproduction event" during the summer, though they typically only breed once per year in normal conditions.

"We can wonder whether this strategy shift may help adaptation of populations to warmer climates over time", said Bestion.
Source: AFP