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Rate of molecular evolution of the seminal protein gene SEMG2 correlates with levels of female promiscuity

Nature Genetics volume 36, pages 13261329 (2004) | Download Citation



Postcopulatory sperm competition is a key aspect of sexual selection and is believed to drive the rapid evolution of both reproductive physiology and reproduction-related genes1,2,3,4. It is well-established that mating behavior determines the intensity of sperm competition, with polyandry (i.e., female promiscuity) leading to fiercer sperm competition than monandry1,2,3. Studies in mammals, particularly primates, showed that, owing to greater sperm competition, polyandrous taxa generally have physiological traits that make them better adapted for fertilization than monandrous species, including bigger testes, larger seminal vesicles, higher sperm counts, richer mitochondrial loading in sperm and more prominent semen coagulation2,5,6,7,8. Here, we show that the degree of polyandry can also impact the dynamics of molecular evolution. Specifically, we show that the evolution of SEMG2, the gene encoding semenogelin II, a main structural component of semen coagulum, is accelerated in polyandrous primates relative to monandrous primates. Our study showcases the intimate relationship between sexual selection and the molecular evolution of reproductive genes.

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We thank W.-H. Huang for technical assistance; A. Di Rienzo, C. Malcom, N. M. Pearson, E. J. Vallender and C.-I Wu for discussions and comments on the manuscript; and L.G. Chemnick, A.R. Ryder and L. Faust for providing primate tissue samples. This work was supported in part by the William Rainey Harper Fellowship (to S.D.) and the Searle Scholarship and the Burroughs Wellcome Career Award (to B.T.L.).

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Author notes

    • Gerald J Wyckoff

    Present address: Division of Biology and Biochemistry, University of Missouri-Kansas City, Kansas City, Missouri, 64108, USA.


  1. Howard Hughes Medical Institute, Department of Human Genetics, University of Chicago, Chicago, Illinois 60637, USA.

    • Steve Dorus
    • , Patrick D Evans
    • , Gerald J Wyckoff
    • , Sun Shim Choi
    •  & Bruce T Lahn
  2. Committee on Genetics, University of Chicago, Chicago, Illinois 60637, USA.

    • Steve Dorus
    •  & Patrick D Evans


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Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Bruce T Lahn.

Supplementary information

PDF files

  1. 1.

    Supplementary Fig. 1

    Lineage-specific ω values of SEMG2 in primates.

  2. 2.

    Supplementary Fig. 2

    Correlation between the evolutionary rate of SEMG2 and the reproductive behavior/physiology in primates.

  3. 3.

    Supplementary Table 1

    Likelihood estimates of different evolutionary models.

  4. 4.

    Supplementary Table 2

    Likelihood ratio between different evolutionary models.

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