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Birds of bright feathers flock with dull boys

In yesterday's USA TODAY, Tim Friend wrote an interesting article from a
study in "Nature" which will brighten up this cloudy day and maybe your
Halloween!  Interesting and can't wait for the pundits to respond!
 Page 1D (Thursday, October 26. 2000)
Birds of bright feathers flock with dull boys
By Tim Friend

Scientists have discovered an unusual form of cooperation among lazuli
bunting finches that allows the most handsome and the least attractive males
to share the top neighborhoods and have the best chance of mating.

The study, in today's Nature, illustrates a rarely observed phenomenon
called ''disruptive selection,'' in which nature favors extreme traits at
both ends of the spectrum at the expense of moderate ones, experts say.

Normally, the forces of natural selection and sexual selection nudge a
species' sexual attractiveness (usually in males) in a direction that
ultimately exaggerates the desirable traits. The male peacock's tail is a
classic example. The most brightly colored or ornamented males are known as

Male lazuli buntings, which vary widely in the brightness of their plumage,
ordinarily appear to follow the standard rules, at least anecdotally, when
their favored habitat of dense bushes or shrubs is plentiful. The dominant
males, which have the brightest feathers, have their pick of territories and
are most successful at attracting females, which are mostly brown.

So the researchers, led by Erick Greene from the University of Montana in
Missoula, were surprised when they discovered that the dullest males in a
lazuli population were mating successfully and living unchallenged in the
best shrubs as neighbors with the hotshots. Meanwhile, the hotshots forced
moderately colored males to settle for scrubby bushes, where they had a
tougher time attracting mates.

The reason for the disruptive selection, in which the dullest males were
sharing at least some of the successes of the dominant males, is probably
explained by a shortage of good housing, researcher Bruce Lyon says.

The area where the disruptive selection was found had a patchy habitat with
fewer available shrubs. Those conditions would intensify the competition for
habitat and females.

But why would the hotshots be so generous to their dull buddies in such
circumstances? The answer appears downright Machiavellian.

''For the dullest males, it may be a bit like making a bargain with the
devil,'' Lyon says.

Equipped with a nice shrub, the dull boys, which appear to ''suck up'' to
the dominant males by hanging out with them on branches, easily attract
mates. That means the hotshots have lots of female neighbors, which accept
less attractive mates to get a good home.

The species is socially monogamous, which means females select one nestmate,
but being socially monogamous does not equal sexual monogamy. DNA testing
found that half the eggs in the nests of the dull dads belonged to other
males. So even though the dull boys get to offer their mates good homes, the
females can't resist the hotshots next door and the chance to pass those
genes along to their offspring.

The trade-off is that the dull and subordinate males, which ordinarily have
difficulty obtaining choice territory and mates, get a nice home and a mate.
The hotshots, for their apparent generosity, fill the neighborhood with
females that find them more sexually attractive than their own mates, Lyon