Some girls want a guy who looks like dear old dad. Stickleback fish want one who smells like him. Researchers have found that in two species of the fish from British Columbia's Paxton Lake, daughters learn who to choose as a mate based on their father's smell, a form of sexual imprinting. One type of stickleback lives in deep water; the other, in waters close to shore. Females of both types lay their eggs in an algae nest the male builds. He then cares for the eggs and fry, as this deep-water form of stickleback is doing above. In laboratory tests, daughters chose mates that smelled like their fathers, researchers report online today in the Proceedings of the Royal Society, B. That keeps the two species apart sexually, helping to reinforce their ecological separation. It's some of the first evidence, the authors say, that sexual imprinting can drive speciation.
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