Evolution cannot outpace climate change

Animals & plants may not be able to evolve their way out of the threat posed by climate change, says a study.

Washington: Animals and plants may not be able to evolve their way out of the threat posed by climate change, says a study.

Many species of animals, birds and plants face stress from climate change, and their habitats have also been fragmented by human activity -- perhaps more than we realise.

For instance, the tide pool copepod Tigriopus californicus, a tiny shrimp like creature, just a millimetre long, is found from Alaska to Baja California - but in a unique lab study, the animals showed little ability to evolve heat tolerance.

"This is a question a lot of scientists have been talking about," said study co-author Eric Sanford, associate professor of evolution and ecology at University of California Davis and a researcher at its Bodega Marine Lab, reports the journal Proceedings of the Royal Society B.

Graduate student Morgan Kelly, study co-author, collected copepods from eight locations between Oregon in the US and Baja California in Mexico. They live in tide pools on rocky outcrops high in the splash zone, according to a California statement.

Kelly grew the short-lived copepods in the lab for 10 generations, subjecting them to increased heat stress to select more heat-tolerant animals.

She was able to coax only about a half-degree Celsius of increased heat tolerance over 10 generations. And in most groups, the increase in heat tolerance had hit a plateau before that point.

In the wild, these copepods can withstand a temperature swing of 20 degrees Celsius a day, Kelly said. But they may be living at the edge of their tolerance, she said.

"The critical point is that many organisms are already at their environmental limits, and natural selection won`t necessarily rescue them," said study co-author Rick Grosberg and professor of evolution and ecology at Davis.


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