Barry Sinervo, a herpetologist at the University of California, Santa Cruz, began to focus on lizard extinctions during fieldwork in France, when he and two French researchers noticed an unsettling pattern of local extinctions while surveying several well-documented populations. Together, they contacted colleagues around the world and built up a large database of similar extinctions in other regions. Concentrating on Mexico, they compared recent and historical surveys for 48 Mexican lizard species at 200 sites and found that 12 per cent of the populations had gone extinct.

The researchers then created a model of extinction risks for various lizard species around the world based on their physiological responses to rising temperatures.

The model accurately predicted specific locations on five continents where lizard populations have recently gone extinct. Projecting the model forward, they found that it predicted that 39 per cent of lizard populations would be extinct by 2080.

The study noted that live-bearing lizards, as opposed to those that lay eggs, are particularly at risk. ‘Live bearers experience almost twice the risk of egg layers largely because live bearers have evolved lower body temperatures,’ Sinervo said.

July 2010