Mating plugs of bank voles promote the transport of one's own sperm, while partially obstructing the ejaculates of rival males, a study finds. Many sexually reproducing animals produce mating plugs, composed of ejaculated proteins that form a solid mass within the female reproductive tract. However, there is limited direct evidence demonstrating the function of these plugs under promiscuous mating conditions, in which males compete for fertilization success. Paula Stockley and colleagues addressed this question by examining female bank voles that mated sequentially with two males. In approximately 25% of cases, the plug of the first male that copulated with the female remained in the female's reproductive tract after the second male had ejaculated, resulting in double plugs from both males. In these cases, the first male's plug partially prevented the sperm of the second male from reaching the uterus. Large plugs deposited by the first male prevented more of the second male's sperm from reaching the uterus, compared with small plugs. Moreover, large plugs facilitated the transport of each male's own sperm. When a greater proportion of the second male's sperm reached the uterus, a greater proportion of the litter was sired by that male. According to the authors, the findings help resolve a longstanding debate by revealing that rodent mating plugs promote fertilization success under competitive conditions.
Article #19-20526: "Revealing mechanisms of mating plug function under sexual selection," by Paula Stockley et al.
MEDIA CONTACT: Paula Stockley, University of Liverpool, UNITED KINGDOM; e-mail: p.stockley@liv.ac.uk
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Proceedings of the National Academy of Sciences