Lost lizards validate grim extinction predictions

Michael Le Page in New Scientist: Predictions that climate change alone could lead to the extinction of more than one-fifth of plant and animal species before the end of the century have often come under fire, and not just from climate-change deniers. Some biologists are sceptical because the predictions are largely based on theoretical models. Now, the most detailed study yet of one group of species – lizards – suggests extinction levels could indeed be as bad as predicted.

Crucially, the new forecast is based on actual data of what is driving lizards to extinction today on four continents.

The international team of researchers led by Barry Sinervo of the University of California, Santa Cruz, found that even though their habitats remained intact, the population of one group of lizards in Mexico has shrunk by 12 per cent since 1975 due to climate change. They found that the reptiles are disappearing because they need to spend more time in the shade to avoid overheating, leaving them less time to find food.
Silent spring

While lizards need to bask in the morning sun to warm up, they have to retreat into the shade later in the day to avoid heat stress. The hotter it gets, the less time they have to forage for food. Surprisingly, though, warmer springs rather than warmer summers are the killer, because this is the time when lizards reproduce and so need lots of extra food.

The team used its data from Mexico to predict where else lizards might be disappearing. They then compared their predictions with field studies of more than 1000 lizard populations on four different continents. They found that their predictions were accurate. Based on this, they predict that 20 per cent of lizard species will be extinct by 2080…

A sand lizard, shot by George Chernilevsky, who has released the image into the public domain