Female meadow voles, Microtus pennsylvanicus, cause their mates to ejaculate outside their reproductive tract


We report the first case of sperm wasting produced by females running away just before a male ejaculates. Consequently, males ejaculate outside the reproductive tract of the female. This behavior was observed at least once in 32.14% of 112 copulatory tests of meadow voles, Microtus pennsylvanicus. We found a negative correlation between percentage of external ejaculations experienced by males and the number of sperm allocated within the female reproductive tract. Thus, females may limit the fertilizing capacity of non-preferred males by causing them to ejaculate externally. The occurrence of external ejaculations was not affected by cues of other males, male body mass, female sexual experience, or male sexual experience. Our results expand the growing view that females may be active participants in copulatory behavior and largely determine the fate and use of sperm. © 2006 Koninklijke Brill NV.

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