Increased Sperm Numbers In The Vas Deferens of Meadow Voles, Microtus Pennsylvanicus, in Response to Odors of Conspecific Males
Document Type
Article
Publication Title
Behavioral Ecology and Sociobiology
Publication Date
5-9-2007
Abstract
Sperm competition occurs when the sperm of two or more males compete to fertilize the egg/s of a particular female. Males of some species respond to a high risk of sperm competition by increasing the number of sperm in their ejaculates. Males may accomplish such a response by increasing the intensity or duration of contraction of the cauda epididymidis and vas deferens. During emission (first phase of the ejaculatory process), the vas deferens receives sperm from the cauda epididymidis and propels the sperm to the urethra. In this paper, we tested the hypothesis that males exposed to a high risk of sperm competition mobilize larger numbers of sperm from the cauda epididymidis to the vas deferens before initiation of copulatory behavior. This accumulation of sperm in the vas deferens would result in a larger number of sperm in the ejaculate. To test this hypothesis, we exposed male meadow voles, Microtus pennsylvanicus, to either low or high risks of sperm competition using soiled bedding of conspecific individuals. At three different times after this exposure (15, 30, or 60 min), we removed both vasa deferentia and counted the sperm within them. We found a significant increase in sperm numbers in the vas deferens of males after 30 min of being exposed to a high risk of sperm competition. The lower sperm numbers after 15 and 60 min of exposure suggest that the observed response is relatively slow and that sperm mobilized to the vasa deferentia may return to the cauda epididymides if ejaculation does not occur some time after the observed response. Our results indicate that the physiological response that may result in high sperm numbers in the ejaculate in relation to high risk of sperm competition can occur before initiation of copulatory behavior.
Funding Source
This work was supported by NSF Grant IOB 0444553 and NIH Grant HD 049525 to MHF.
Recommended Citation
delBarco-Trillo, Javier and Ferkin, Michael H., "Increased Sperm Numbers In The Vas Deferens of Meadow Voles, Microtus Pennsylvanicus, in Response to Odors of Conspecific Males" (2007). Faculty Publications – Biological Sciences. 167.
https://ir.library.illinoisstate.edu/fpbiosci/167
DOI
https://doi.org/10.1007/s00265-007-0408-0
Comments
This article was originally published as delBarco-Trillo, J. and Ferkin, M.H. (2007) Increased sperm numbers in the vas deferens in response to odors of conspecific males in the meadow vole, Microtus pennsylvanicus. Behavioral Ecology and Sociobiology. 61: 1759-1764. https://doi.org/10.1007/s00265-007-0408-0.