Evolution isn't generally considered a race, but no matter - the tiny stickleback fish is a clear winner. Faced with suddenly colder water, the species managed to adapt in record time - fast enough to potentially beat climate change.
Stickleback fish are very small, no more than ten centimeters long. They originated in the oceans, but after the end of the last Ice Age some 10,000 years ago part of the species split off and colonized freshwater rivers and lakes. The two different groups have since developed very different physical features and behaviors to cope with their surroundings. All of these features made them the perfect candidates to test the speed of their evolutionary processes.
Researchers at the University of British Columbia determined that the freshwater variety of stickleback fish can handle colder temperatures than their oceangoing counterparts, almost certainly because lakes and streams reach far colder temperatures than oceans ever do. To test how fast this adaptation occurred, the researchers, working with colleagues from Sweden and Switzerland, took a bunch of ocean stickleback fish and dropped them in freshwater ponds.
In just three years, the transplanted fish - or, more accurately, their third generation descendants - could handle temperatures 2.5 degrees Celsius colder than they could in the oceans. That's a fairly sizable shift in average temperature, and this speedy adaptation - one that's particularly fast for such a relatively complex organism - sheds an interesting light on how some species might deal with the temperature swings caused by climate change.
UBC researcher Rowan Barrett explains:
"Scientific models have suggested that climate change could result in both a general, gradual increase of average temperatures and an increase in extreme temperatures," says Barrett, who received his PhD last week. Our study is the first to experimentally show that certain species in the wild could adapt to climate change very rapidly - in this case, colder water temperature."
That said, he is hardly suggesting we shouldn't worry about the effects of climate change on such species:
"However, this rapid adaptation is not achieved without a cost. Only rare individuals that possess the ability to tolerate rapid changes in temperature survive, and the number of survivors may not be large enough to sustain the population. It is crucial that knowledge of evolutionary processes is incorporated into conservation and management policy."