Waterfowl wage genital warfare...(Paging Mr. Darwin)

[SoCalDem]

Waterfowl wage genital warfare
'Arms race' has resulted in longer phalluses, more elaborate vaginas

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By Charles Q. Choi
LiveScience

Updated: 6:30 p.m. PT April 30, 2007

A sexual arms race waged with twisted genitals has been discovered in waterfowl. The genitalia of the females of these species have at times apparently evolved to make it harder for males to successfully impregnate them, according to new findings that shed light on the eternal war of the sexes.

Most birds lack phalluses, organs like human penises. Waterfowl are among the just 3 percent of all living bird species that retain the grooved phallus found in their reptilian ancestors. Male waterfowl are especially unusual in that their phallus length varies greatly among different species, ranging from a half-inch to more than 15 inches long. They also display a remarkable level of diversity how elaborate they are, ranging from smooth to covered with spines and grooves. Scientists had speculated that male waterfowl evolved longer phalluses to give them a competitive edge over those not as well-endowed when it came to successfully fertilizing females.

After looking at the genitalia of a male duck, "I became immediately intrigued by what the female anatomy would look like to accommodate such a bizarre organ," said behavioral ecologist Patricia Brennan, who researches at both Yale University and the University of Sheffield in Britain. Now Brennan and her colleagues unexpectedly find the vaginas of female waterfowl can be just as ornate as male genitalia, full of "dead ends" and other countermeasures that all seemed design to exclude the phallus, findings to be detailed online May 2 in the journal PLoS ONE.

Like lock and key
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