A study of tiny stickleback fish has shown how evolution might help species adapt to climate change.

In a novel experiment, zoologists took sticklebacks from the ocean and released them in ponds where the water was colder. Within three years, the "grandchildren" of the original sticklebacks could tolerate water 2.5C colder than their ancestors - one of the fastest evolutionary responses recorded in a wild population.

Researchers say the paper, published in the current issue of the Proceedings of the Royal Society B, is among the first experimental evidence that evolution could help species adapt to climate change.

"What we are beginning to realise is that evolution can happen at rates more rapid than we previously appreciated," said lead researcher Rowan Barrett, a PhD graduate in zoology at the University of British Colombia. In the latest experiment, researchers from Canada, Switzerland and Sweden re-created ancient history by putting ocean fish in colder fresh water. The catch was that all of the sticklebacks in the study eventually died.

Barrett said the fish were under immense pressure because only a small number carried the right gene mutations to adapt. The majority that could not adapt died quickly and the remainder died after a cold winter three years into the study.

Now Barrett wants to find out which stickleback genes are important for temperature tolerance and - crucially - whether they can adapt to warmer as well as cooler temperatures.

Stickleback study

- Took fish from ocean and placed in ponds where water was colder.

- Periodically caught fish in nets and tested them for tolerance to cold.

- After three years, third generation of sticklebacks could cope with water 2.5C colder than their grandparents.

- Researchers say fish population changed its genetic make-up to cope with cold.