Tiny Fish Evolved to Tolerate Colder Temperature

University of British Columbia researchers have observed one of the fastest evolutionary responses ever recorded in wild populations. In as little as three years, stickleback fish developed tolerance for water temperature 2.5 degrees Celsius lower than their ancestors.

The study, published in the current issue of the Proceedings of the Royal Society B, provides the some of the first experimental evidence that evolution may help populations survive effects of climate change.

Measuring three to 10 centimetres, stickleback fish originated in the ocean but began populating freshwater lakes and streams following the last ice age. Over the past 10,000 years, marine and freshwater sticklebacks have evolved different physical and behavioural traits, making them ideal models for Darwin's natural selection theory.

To learn how quickly this adaptation took place, Barrett and colleagues from Switzerland and Sweden "recreated history" by transplanting marine sticklebacks to freshwater ponds and found that in as little as three generations (or three years), they were able to tolerate the same minimum temperature as freshwater sticklebacks, 2.5 °C lower than their ancestral populations.

It is crucial that knowledge of evolutionary processes is incorporated into conservation and management policy.