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Proc Biol Sci. 2002 January 22; 269(1487): 165–172.
PMCID: PMC1690873

Age-dependent sexual selection in bighorn rams.

Abstract

Although mating systems and sexual selection have been intensively studied in ungulate model systems, very few studies have combined genetic paternity analysis with individual phenotypic data over several breeding seasons. We used microsatellite paternity analysis to determine the parentage of 83 bighorn sheep (Ovis canadensis) born between 1995 and 2000 at Ram Mountain, Alberta, Canada. We could assign the paternity of 64 lambs at a high level of statistical confidence (95%). Within each season, the most successful ram sired an average of 35.5% of the lambs with assigned paternity, and a single ram sired 26.1% of all lambs over the six mating seasons. Although a few large-horned, mature (age 8+ years) rams had very high reproductive success, younger rams sired ca. 50% of the lambs. Mixed-effects models indicated that mating success increases as a nonlinear function of age, with horn length increasingly positive in correlation with mating success in older rams. These results indicate that young or small rams possibly achieve mating success through alternative mating tactics that are less dependent on body and weapon size, such as coursing and blocking. Sexual selection is therefore likely to have age-dependent effects on traits such as agility, body and horn size.

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Selected References

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  • Bishop MD, Kappes SM, Keele JW, Stone RT, Sunden SL, Hawkins GA, Toldo SS, Fries R, Grosz MD, Yoo J, et al. A genetic linkage map for cattle. Genetics. 1994 Feb;136(2):619–639. [PubMed]
  • Buchanan FC, Crawford AM. Ovine dinucleotide repeat polymorphism at the MAF209 locus. Anim Genet. 1992;23(2):183–183. [PubMed]
  • Buchanan FC, Crawford AM. Ovine microsatellites at the OarFCB11, OarFCB128, OarFCB193, OarFCB266 and OarFCB304 loci. Anim Genet. 1993 Apr;24(2):145–145. [PubMed]
  • Coltman DW, Bancroft DR, Robertson A, Smith JA, Clutton-Brock TH, Pemberton JM. Male reproductive success in a promiscuous mammal: behavioural estimates compared with genetic paternity. Mol Ecol. 1999 Jul;8(7):1199–1209. [PubMed]
  • Coltman DW, Smith JA, Bancroft DR, Pilkington J, MacColl AD, Clutton-Brock TH, Pemberton JM. Density-dependent variation in lifetime breeding success and natural and sexual selection in Soay rams. Am Nat. 1999 Dec;154(6):730–746. [PubMed]
  • CROW JF. Some possibilities for measuring selection intensities in man. Hum Biol. 1958 Feb;30(1):1–13. [PubMed]
  • de Gortari MJ, Freking BA, Kappes SM, Leymaster KA, Crawford AM, Stone RT, Beattie CW. Extensive genomic conservation of cattle microsatellite heterozygosity in sheep. Anim Genet. 1997 Aug;28(4):274–290. [PubMed]
  • Ede AJ, Pierson CA, Crawford AM. Ovine microsatellites at the OarCP9, OarCP16, OarCP20, OarCP21, OarCP23 and OarCP26 loci. Anim Genet. 1995 Apr;26(2):129–130. [PubMed]
  • Emlen ST, Oring LW. Ecology, sexual selection, and the evolution of mating systems. Science. 1977 Jul 15;197(4300):215–223. [PubMed]
  • Engelke DR, Krikos A, Bruck ME, Ginsburg D. Purification of Thermus aquaticus DNA polymerase expressed in Escherichia coli. Anal Biochem. 1990 Dec;191(2):396–400. [PubMed]
  • Fisher DO, Lara MC. Effects of body size and home range on access to mates and paternity in male bridled nailtail wallabies. Anim Behav. 1999 Jul;58(1):121–130. [PubMed]
  • Hogg JT. Mating in bighorn sheep: multiple creative male strategies. Science. 1984 Aug 3;225(4661):526–529. [PubMed]
  • Kruuk LE, Clutton-Brock TH, Rose KE, Guinness FE. Early determinants of lifetime reproductive success differ between the sexes in red deer. Proc Biol Sci. 1999 Aug 22;266(1429):1655–1661. [PMC free article] [PubMed]
  • Marshall TC, Slate J, Kruuk LE, Pemberton JM. Statistical confidence for likelihood-based paternity inference in natural populations. Mol Ecol. 1998 May;7(5):639–655. [PubMed]
  • Penty JM, Henry HM, Ede AJ, Crawford AM. Ovine microsatellites at the OarAE16, OarAE54, OarAE57, OarAE119 and OarAE129 loci. Anim Genet. 1993 Jun;24(3):219–219. [PubMed]
  • Preston BT, Stevenson IR, Pemberton JM, Wilson K. Dominant rams lose out by sperm depletion. Nature. 2001 Feb 8;409(6821):681–682. [PubMed]
  • Reale D, Festa-Bianchet M, Jorgenson JT. Heritability of body mass varies with age and season in wild bighorn sheep. Heredity (Edinb) 1999 Nov;83(Pt 5):526–532. [PubMed]
  • Swarbrick PA, Buchanan FC, Crawford AM. Ovine dinucleotide repeat polymorphism at the MAF36 locus. Anim Genet. 1991;22(4):377–378. [PubMed]
  • Wilson GA, Strobeck C, Wu L, Coffin JW. Characterization of microsatellite loci in caribou Rangifer tarandus, and their use in other artiodactyls. Mol Ecol. 1997 Jul;6(7):697–699. [PubMed]

Articles from Proceedings of the Royal Society B: Biological Sciences are provided here courtesy of The Royal Society