Fellow diners make excellent mates — at least when it comes to stickleback fish, according to a University of British Columbia study that provides the clearest evidence to date that local adaptation can change mating preferences.
UBC Zoology post-doctoral fellow Tim Vines studied populations of stickleback fish from four separate lakes in British Columbia. Two of the populations have adapted to feeding in open water while the other two feed on the lakebed.
The study, to be published in the April 22 edition of the Proceedings of the Royal Society B, has broad implications because it shows how adaptation within a species (microevolution) can create new species (macroevolution), and thereby contribute to biodiversity.
Measuring 3.7 to 10 centimetres long, sticklebacks are widely distributed in fresh and salt waters in the Northern Hemisphere. Their elegant courtship behaviours and capacity to adapt to many different freshwater habitats make them prime subjects for studying the evolution of mate preferences.
“We found that when given a choice between unfamiliar males from other lakes, females almost always chose the male from their own feeding environment,” says Vines.
The discovery provides clues as to why distinct species of stickleback fish — distinguished by their feeding patterns — co-exist in some B.C. lakes. “The phenomenon we observed may well have been the first step in these populations evolving into separate species.”
“Adaptation somehow changes mate preferences so females only accept mates from their own environment, effectively stopping interbreeding between populations in different habitats. This in turn allows populations to diverge into new species.”
Note to Editors: Pictures of stickleback fish are available upon request.
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