What looks like the ultimate bad choice in romance–a mate from a different species–in some conditions may not be so dumb after all, according to a new analysis of flycatchers.
Two European species do face some poor consequences when they mix, acknowledges Ben C. Sheldon of the University of Oxford in England. Yet mismatched birds show quirks that reduce the damage, such as a good sex ratio of nestlings and an extra willingness to sneak off for a quick visit to a member of the right species.
For birds starting late in mating season, such patterns can make up for the lowered fertility of the mixed-species nest, Sheldon and his team report in the May 3 Nature. "It was quite amazing when you actually did the sums," he says. "An apparently highly maladaptive behavior turns out to be an adaptation."
He predicts that the flycatcher study will affect ideas about such evolutionary puzzles as how species split apart and why birds cuckold their mates.