Researchers have found that tiny fish called sticklebacks can adapt rapidly to a decrease in water temperature. This discovery adds to a long and growing list of animal trait variations that happen quickly. The researchers cited the stickleback adaptation as an example of evolution in action, but the rapidity of this change identifies it as the result of intentional programming–not mindless mutations.
The tiny stickleback seems to have a history of adaptability. A University of British Columbia press release indicated that populations of these fish once lived in the ocean, but then moved to live in freshwater lakes and streams.1 Other marine fish have been found with the ability to thrive in fresh water in only a few generations, like the pompano populations that are bred for freshwater fish farming.2
A team of Canadian and European scientists transplanted sticklebacks from Oyster Lagoon in southwest British Columbia to cold freshwater ponds. In just three years, which corresponds to three generations, stickleback fish “developed tolerance for” water that is 4.5 degrees Fahrenheit colder than the marine population’s habitat.1
By the third generation, descendants remained of those “rare individuals” that already had the capacity to tolerate cold before the experiment began.1 The study authors wrote, “This rate of phenotypic evolution is among the most rapid to be observed in a natural population.”3….
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