Homosexual Beetle Activity Offers Reproductive Edge

Matt Kaplan
for National Geographic News
November 4, 2008

Homosexual activity among male flour beetles can actually increase the insects' chances of reproducing, a new study finds.

This behavior in the 0.13-inch-long (three-millimeter-long) Tribolium castaneum, which can be found infesting flour in most temperate areas, has been observed for decades.

From an evolutionary perspective, why homosexuality exists at all is a mystery. In theory, males should focus their energies on reproducing with females.

"We noticed that these male beetles spent quite a lot of time in this seemingly counterproductive behavior and wondered what was going on, so we set up some experiments to find out," said lead author Sara Lewis, an evolutionary ecologist at Tufts University in Medford, Massachusetts.

Her findings appear in the Journal of Evolutionary Biology.

Homosexual behavior has been seen in many animals, including insects, penguins, and primates.

(Related: "Homosexual Activity Among Animals Stirs Debate" [July 23, 2004].)

Some researchers suggest that male animals need to practice breeding as much as they can before meeting females.

Others argue that males need to get rid of old, less effective sperm before they encounter females.

Some scientists have even asserted that homosexual behavior is a method of exerting social dominance over other males.

Tracking Success

Lewis's team marked individual males and females, then tracked their sexual exploits while simultaneously monitoring the paternity of any offspring born in the group.

Continued on Next Page >>


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