Climate change sparks 'quickest evolution ever'

Yahoo News 7 Aug 10;

VANCOUVER, Canada (AFP) – At least one fish species can adapt in just three generations to survive a sharp change in temperature, researchers said in a study on the fastest rate of evolution ever recorded in wild animals.

"Our study is the first to experimentally show that certain species in the wild could adapt to climate change very rapidly," said Friday lead researcher Rowan Barrett.

However, the University of British Columbia evolutionary geneticist warned, the evolutionary jump carries a deadly price tag: a high mortality rate.

In their research, scientists from Canada and Europe removed marine stickleback fish from the ocean, put them into ponds with gradually dropping temperatures, and studied them for three years.

Over three generations, one per year, the fish evolved to survive water 2.5 degrees Celsius below the limit for their great grandparents, said the study released online and to be published in the September 7 issue of the Proceedings of the Royal Society B.

The findings suggest at least some animals may be able to change quickly enough to survive predicted climate change.

Virtually all climate research in peer-reviewed science journals predicts global temperatures will gradually rise by several degrees in coming decades, accompanied by swings of extreme cold and heat.

"But just because we've seen a large evolutionary response, that doesn't mean a natural population can adapt to climate change with no consequences," Barrett told AFP Thursday.

About 95 per cent of the fish population died during the three-year study, with only five per cent developing a tolerance for cold," he said.

"The consequences of losing 95 per cent might be catastrophic, because the remaining five per cent might not be able to sustain the population," said Barrett.

He added: "We don't know the genetic basis of this trait."

Barrett, who is moving to Harvard after completing a PhD at UBC, said more research is needed to determine whether such rapid evolution can occur in other species and -- most critically -- to warming instead of cooling.

He said such research may also hold clues for how humans will cope with climate change.

The rapid evolution by the marine fish in the study mirrored the 10,000-year-long evolution of freshwater stickleback in British Columbia - descendants of marine fish trapped inland at the end of the last Ice Age, who evolved to live in extreme cold.

Barrett noted that humans also evolved over some 10,000 generations, since their first migration from Africa, raising the question of how many generations it might take for northern peoples to evolve genes that could cope with warmer climates experienced by their African ancestors.

"You can start to draw a parallel in evolutionary rates," said Barrett.

But he warned that, as shown by the 95 per cent mortality rate in the stickleback, such rapid evolution "can make the population extremely vulnerable... there are always consequences."