Warming might defeat species evolution, University of Arizona professor says

Rapid temperature rise could endanger many species, UA prof says
2013-07-28T00:00:00Z Warming might defeat species evolution, University of Arizona professor saysTom Beal Arizona Daily Star Arizona Daily Star
July 28, 2013 12:00 am  • 

Vertebrates would have to evolve 10,000 times faster than they ever have to keep up with the pace of change predicted for their climatic niches in the next century, says a University of Arizona researcher.

"If where they live now is going to be outside their climatic niche, they either have to move or acclimate to it," said John Wiens, UA professor of ecology and evolutionary biology.

Acclimating can be a tricky thing, Wiens said.

Some lizard and tortoise species in warming climates have been known to limit their outdoor exposure when their particular niche warms up, he said. That lessens the physiological impact of heat, but also deprives them of time for food gathering and reproducing, he said.

Wiens and co-author Ignacio Quintero, an ecologist at Yale University, examined and compared the evolutionary paths of more than 500 species, from weasels to frogs to crocodiles, to arrive at their conclusions about what would be needed to survive a predicted rise of 4 degrees Centigrade in average temperatures by the end of the century.

They found that evolution can't keep pace with the rapid change in climate predicted by the Intergovernmental Panel on Climate Change - not by a long shot.

Some of the species have survived for millions of years. They obviously survived without evolving through swings in temperature - ice ages and warm periods - probably by moving.

But lizards and frogs don't move quickly, he said. "It's not like humans living in Detroit who can say: 'It sucks here. I'm going to hop in my car and go.' "

Those glaciations and thaws occurred slowly over tens of thousands of years.

Four degrees in 80 years is a quick pace. "Evolving at that rate is possible but would be unprecedented. They might be able to do this thing they've never done before but all the evidence is against it."

Evolution is not the only answer to climate change, he said, but the options are limited.

Even if species could move quickly, natural barriers and destruction of habitat limit that movement.

In Arizona's Sky Island ecology, species are already moving higher as temperatures warm.

Researchers at the University of Arizona used data gathered by Dave Bertelsen during 20 years of daily hikes on the Finger Rock Trail in the Santa Catalina Mountains to demonstrate the upward movement of plants in response to warming.

Ecologist Theresa Crimmins and her husband, Michael, a climatologist, compared the first decade of Bertelsen's observations to the second in a paper published by the trio in 2009 in Global Change Biology.

A little more than 25 percent of the 360 plant species showed a change in elevation range, said Theresa Crimmins, with more than 85 percent of the movement in the uphill direction.

Crimmins is partnerships and outreach coordinator of USA National Phenology Network, which tracks key seasonal changes in plants and animals - phenomena such as leaf-out, blooming and migration.

The trends are pretty clear, she said. Warming is causing movement of species by altitude and latitude and disconnecting migratory birds from food supplies.

Wiens said the warming of the past 30 years is already disrupting the ecological niches of species. That's with a 0.6-degree C (1.08 degrees F) rise in global temperatures. With four more degrees (7.2 degrees F) predicted by 2100, the damage will worsen, he said.

"If dispersal, acclimation or adaptation do not occur, then the population may go extinct, especially if climate change pushes local conditions outside the fundamental climatic niche of the population or species," the report says.

Wiens said his study is not predicting mass global extinctions as a result of climate change. "But we're not 'not predicting' it either."

Wiens said the biggest threat to species diversity is destruction of habitat but a warming world could accelerate rates of extinction.

TV 'oops' goes viral

UA professor John Wiens got a lot of attention from his recent paper on evolution and climate change, but it was an interviewer's gaffe that went viral and eventually made its way to the David Letterman Show.

Wiens was interviewed on CNN International by Jonathan Mann, who prefaced a question with the statement that man-made extinctions are nothing new. "I guess we hunted the dildo into extinction," he said, before quickly correcting himself. "The dodo, forgive me. I'm having trouble with my words today."

Contact reporter Tom Beal at tbeal@azstarnet.com or 573-4158.

Copyright 2014 Arizona Daily Star. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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