A wave of reptile extinctions on the Greek islands over the past 15,000 years may offer a preview of the way plants and animals will respond as the world rapidly warms due to human-caused climate change, according to SNRE Associate Professor Johannes Foufopoulos and his colleagues.

As the climate warmed at the tail end of the last ice age, sea levels rose and formed scores of Aegean islands that had formerly been part of the Greek mainland. At the same time, cool and moist forested areas dwindled as aridity spread through the region.

In response to the combined effects of a shifting climate, vegetation changes, ever-decreasing island size and increasingly fragmented landscape, many reptile populations perished. Today, in many places, small chunks of natural habitat are surrounded by vast, inhospitable expanses of agricultural and urbanized land, just as the Aegean islands were surrounded by rising seas thousands of years ago. The researchers conclude that a similar pattern of extinctions will emerge across the globe as the climate warms.

"The widespread fragmentation of natural habitats greatly exacerbates the effects of climate change and undermines the ability of species to adapt to the new conditions," said Foufopoulos. "The lessons learned from the wave of reptile extinctions suggest that if species are to survive the global climate shift already underway, not only do humans have to set significantly more land aside for conservation, but these protected areas will also need to be connected through a network of habitat corridors that allow species migration."

To gain a clearer understanding of the past consequences of climate change, Foufopoulos and his colleagues calculated the population extinction rates of 35 reptile species—assorted lizards, snakes and turtles—from 87 Greek islands in the northeast Mediterranean Sea. The calculated extinction rates were based on the modern-day presence or absence of each species on islands that were connected to the mainland during the last ice age.

Foufopoulos and his colleagues found a striking pattern to the island extinctions. In most cases, reptile populations disappeared on the smallest islands first—the places where the habitat choices were most limited.

The study results appear in the January edition of American Naturalist.