Syracuse University researchers pick up where Darwin left off: Groundbreaking study to be published in the Nov. 8 issue of Science
When it comes to mating and determining whose sperm reaches the elusive egg, females control both the playing field and the rules of the game, according to a new study on male sperm competition vs. female choice to be published in the Nov. 8 issue of Science.
"Our study demonstrates, unambiguously, the active role females play in determining the conditions under which sperm compete inside the female reproductive tract," says Scott Pitnick, professor of biology at Syracuse University, who published the study with co-researcher Gary T. Miller, a postdoctoral research associate at SU. "Its widely known that, throughout the animal kingdom, sperm cells evolve rapidly into some of the most outrageous variations in size and shape. Until now, we didnt know why. Our study shows that its because of female choice. The shape and physiology of the female reproductive tract is driving this variation in sperm."
Most people are familiar with the elaborate competitions that occur between males before mating, such as the ritualistic clash of horns of Big Horn Sheep or the bloody battles between male elephant seals. However, relatively little is understood about how sperm compete after mating has occurred, says Pitnick, an evolutionary biologist who has been studying sexual selection and the nature of sex differences for more than 15 years. In a 1995 study published in Nature, he documented the longest sperm cell known to science. It belongs to a species of fruit fly called Drosophila bifurca and measures some two inches in length when fully uncoiled.
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