If you can't look brilliant, forget halfway–decent looks. Go for total loser.
That fashion tip works—in male lazuli buntings—because their blue plumage shows signs of a rarely documented evolutionary pattern called disruptive selection, contend Erick Greene of the University of Montana in Missoula and his colleagues in the Oct. 26 Nature. Disruptive selection favors individuals with either of the opposite extremes of a trait and discourages moderation.
Among year-old males, "the really, really dull guys and the really, really bright guys do best," says coauthor Bruce E. Lyon of the University of California, Santa Cruz. Those extremes tend to win mates and good territories, whereas the males with moderately blue plumage lose out.