Environment, Headlines, North America

ENVIRONMENT: Climate Change Spurs Genetic Adaptation in Animals

Stephen Leahy

BROOKLIN, Canada, Feb 28 2003 (IPS) - While politicians and researchers debate the realities of climate change, plants and animals worldwide are already adapting. Red squirrels in Canada’s North now give birth weeks earlier so their young can take advantage of the shorter winters that have come with increasing global temperatures.

The signs of early spring are increasingly seen in northern Canada: glaciers are receding, permafrost regions melting and thunderstorms echoing for the first time in lands that used to be too cold for them.

North American red squirrels in the southwest Yukon Territory began breeding earlier so their young could take advantage of increasingly warm spring temperatures and the corresponding increase in food, says Stan Boutin, a biologist at the University of Alberta in Edmonton who has studied the animals for more than 10 years.

They found the squirrels now breed 18 days sooner than 10 years ago. ”We were very surprised by the results,” said Boutin.

Using analytical modelling the researchers were able to determine that much of the squirrel’s adaptation is due to its ability to adjust its behaviour to climatic conditions. But careful analysis revealed an inherited genetic change that advanced breeding one day per generation, Boutin said.

Four generations have since passed and even if spring comes late next year, the squirrels will breed four days sooner. "We’re now trying to identify the specific genetic changes but it’s likely to involve many different genes,” added the researcher.

Although this first documentation of an animal changing its genetic make-up appears to be a successful adaptation to cope with global warming, the future is still a concern, according to Boutin.

First, squirrels are a highly adaptable species but that is probably not the case for many other animals. It is also possible that the squirrels have already reached the limit of their genetic flexibility; and even if they have not, they might not be able to keep pace with changing climatic conditions, he added.

”The worst-case scenario is the extinction of the species,” says Boutin.

Plants and animals in other parts of the world are also responding to these changes. Two massive studies published in the science journal ‘Nature’ earlier this year found that many species have extended their ranges northward to keep up with the earlier arrival of spring because of a 0.6 Celsius global temperature increase in the past 100 years. Scientists believe a 6C rise is possible by 2100.

”Birds are laying eggs earlier than usual, plants are flowering earlier and mammals are breaking hibernation sooner,” said Terry L. Root, a senior fellow with Stanford University’s Institute for International Studies. If such changes are already being detected, then many more far-reaching effects on species and ecosystems will probably occur by 2100, said Root in a press release.

The researcher and her colleagues analysed 143 scientific studies involving 1,473 species of animals and plants. Each study found a direct correlation between global warming and biological change somewhere in the world.

For example, several studies revealed that as temperatures increased in recent decades, certain species began breeding and migrating earlier than expected. Other studies found that the geographical range of numerous species had shifted pole ward or moved to a higher elevation – indicating that some plants and animals are occupying areas that were previously too cold for survival.

Measurements taken in Alaska found that growth in cold-loving white spruce trees was significantly stunted in recent years – another expected consequence of a rapidly warming climate, Root said. ”Climate change models predict that the poles will warm more quickly than the equator.”

In temperate zones, the scientists found that springtime events – such as blooming, egg laying and the end of hibernation – now occur about 5.1 days earlier per decade on average.

In the tropics, scientists at Conservation International (CI) have learned that climate change will badly hurt some of the world’s biodiversity hotspots. A warming and drying trend will devastate the remarkable plant life found in the Succulent Karoo, a 112,000 square kilometre area located on the western edge of South Africa and Namibia. About 2,000 of the nearly 5,000 plants found there occur nowhere else on Earth.

If present trends continue, the Karoo will be eliminated in all but tiny patches, possibly as early as mid-century if present emissions trends continue, said Lee Hannah, a climate change scientist at CI.

Another biodiversity hotspot at risk is South America’s Andes Mountains, where the golden toad of the Costa Rican cloud forests is now extinct largely due to climate change.

The Andes are a complex hydrological system in which the cloud forest migrates up slope. If climate change forces warmer areas to move up the mountains then the cloud forest zone – the area richest in floral and fauna – will become narrower, according to Mark Bush of the Florida Institute of Technology. Conservation of climate regions is as important as conservation of lands, he added.

Climate change is also being blamed for a global coral-bleaching event in 1998 that affected 90 percent of the world’s coral; in some areas, the recovery rate has been as low as 10 percent.