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Home / Equine Research Bank / Proc Natl Acad Sci U S A / Social bonds between unrelated females increase reproductive...
Proceedings of the National Academy of Sciences of the United States of America2009; 106(33); 13850-13853; doi: 10.1073/pnas.0900639106

Social bonds between unrelated females increase reproductive success in feral horses.

Abstract: In many mammals, females form close social bonds with members of their group, usually between kin. Studies of social bonds and their fitness benefits have not been investigated outside primates, and are confounded by the relatedness between individuals in primate groups. Bonds may arise from kin selection and inclusive fitness rather than through direct benefits of association. However, female equids live in long-term social groups with unrelated members. We present 4 years of behavioral data, which demonstrate that social integration between unrelated females increases both foal birth rates and survival, independent of maternal habitat quality, social group type, dominance status, and age. Also, we show that such social integration reduces harassment by males. Consequently, social integration has strong direct fitness consequences between nonrelatives, suggesting that social bonds can evolve based on these direct benefits alone. Our results support recent studies highlighting the importance of direct benefits in maintaining cooperative behavior, while controlling for the confounding influence of kinship.
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Publication Date: 2009-08-10 PubMed ID: 19667179PubMed Central: PMC2728983DOI: 10.1073/pnas.0900639106Google Scholar: Lookup
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  • Non-U.S. Gov't

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research study explores the impact of social relationships among unrelated female horses on their reproductive success. The study illustrates that such social interactions lead to higher foal birth rates and survival, and lesser harassment by males, regardless of other factors like habitat quality, group type, age, or dominance status.

Objective of the Research

  • The objective of this research was to understand the role of social bonds in reproductive success among unrelated females in animal groups where such social interactions are prevalent. Specifically, the research aimed to investigate these relationships among female feral horses, a species where long-term social groups include unrelated individuals.

Methodology

  • The study utilized four years of behavioral data collected from female feral horses. This extensive timeline provided the researchers with an opportunity to observe the long-term outcomes of social integration across different group settings and individual circumstances.
  • Key elements considered in the research included foal birth rates and survival, levels of harassment by males, and factors such as maternal habitat quality, social group type, dominance status, and age.

Findings

  • The study found that there was indeed a positive correlation between social integration among unrelated females and reproductive success. Specifically, the research demonstrated that unrelated females who were more socially integrated had higher foal birth rates and survival.
  • Another critical finding was that higher social integration appeared to lead to reduced male harassment, providing a direct tangible benefit for the socially integrated females.

Implications of the Research

  • These findings suggest that social bonds form not just due to kin selection and inclusive fitness, but also due to the direct benefits that result from association with others.
  • The results emphasize the importance of direct benefits in maintaining cooperative behavior, even in the absence of kinship. This implies that social interaction can enhance reproductive success even among unrelated individuals, an insight that may impact our understanding of social dynamics in animal groups.

Cite This Article

APA
Cameron EZ, Setsaas TH, Linklater WL. (2009). Social bonds between unrelated females increase reproductive success in feral horses. Proc Natl Acad Sci U S A, 106(33), 13850-13853. https://doi.org/10.1073/pnas.0900639106

Publication

Proceedings of the National Academy of Sciences of the United States of America
ISSN: 1091-6490
NlmUniqueID: 7505876
Country: United States
Language: English
Volume: 106
Issue: 33
Pages: 13850-13853

Researcher Affiliations

Cameron, Elissa Z
  • Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa. ezcameron@zoology.up.ac.za
Setsaas, Trine H
    Linklater, Wayne L

      MeSH Terms

      • Animals
      • Behavior, Animal
      • Birth Rate
      • Cooperative Behavior
      • Female
      • Horses
      • Male
      • Reproduction / physiology
      • Risk
      • Sexual Behavior, Animal
      • Time Factors

      Conflict of Interest Statement

      The authors declare no conflict of interest.

      References

      This article includes 55 references
      1. Smuts BB, Smuts RW. Male aggression and sexual coercion of females in non-human primates and other mammals: Evidence and theoretical implications.. Adv Stud Behav 1991;22:1–63.
      2. Réale D, Bousses P, Chapuis J-L. Female-biased mortality induced by male sexual harassment in a feral sheep population.. Can J Zool 1996;74:1812–1818.
      3. Kappeler PM. Determinants of primate social organization: comparative evidence and new insights from Malagasy lemurs.. Biol Rev Camb Philos Soc 1997 Feb;72(1):111-51.
        pubmed: 9116164doi: 10.1017/s0006323196004999google scholar: lookup
      4. Clutton-Brock TH, Price OF, MacColl ADC. Mate retention, harassment and the evolution of ungulate leks.. Behav Ecol 1992;3:234–242.
      5. van Schaik CP, Kappeler PM. Infanticide risk and the evolution of male-female association in primates.. Proc Biol Sci 1997 Nov 22;264(1388):1687-94.
        pmc: PMC1688726pubmed: 9404030doi: 10.1098/rspb.1997.0234google scholar: lookup
      6. Linklater WL, Cameron EZ, Minot EO, Stafford KJ. Stallion harassment and the mating system of horses.. Anim Behav 1999 Aug;58(2):295-306.
        pubmed: 10458881doi: 10.1006/anbe.1999.1155google scholar: lookup
      7. Feh C, de Mazières J. Grooming at a preferred site reduces heart rate in horses.. Anim Behav 1993;46:1191–1194.
      8. Hennessy MB, Zate R, Maken DS. Social buffering of the cortisol response of adult female guinea pigs.. Physiol Behav 2008 Mar 18;93(4-5):883-8.
        pubmed: 18221759doi: 10.1016/j.physbeh.2007.12.005google scholar: lookup
      9. Wittig RM, Crockford C, Lehmann J, Whitten PL, Seyfarth RM, Cheney DL. Focused grooming networks and stress alleviation in wild female baboons.. Horm Behav 2008 Jun;54(1):170-7.
        pmc: PMC4280186pubmed: 18396288doi: 10.1016/j.yhbeh.2008.02.009google scholar: lookup
      10. Kaplan JR. The relationship of agonistic and affiliative behavior patterns to cellular immune function among cynomolgus monkeys (Macaca-fascicularis) living in unstable social-groups.. Am J Primatol 1991;25:157–173.
      11. Cheney D, Seyfarth R, Smuts B. Social relationships and social cognition in nonhuman primates.. Science 1986 Dec 12;234(4782):1361-6.
        pubmed: 3538419doi: 10.1126/science.3538419google scholar: lookup
      12. Silk JB. Using the ‘F’-word in primatology.. Behaviour 2002;139:421–446.
      13. Cords M. Friendship among adult female blue monkeys (Cercopithecus mitis). Behaviour 2002;139:291–314.
      14. Silk JB. The adaptive value of sociality in mammalian groups.. Philos Trans R Soc Lond B Biol Sci 2007 Apr 29;362(1480):539-59.
        pmc: PMC2346516pubmed: 17363359doi: 10.1098/rstb.2006.1994google scholar: lookup
      15. Silk JB, Alberts SC, Altmann J. Social bonds of female baboons enhance infant survival.. Science 2003 Nov 14;302(5648):1231-4.
        pubmed: 14615543doi: 10.1126/science.1088580google scholar: lookup
      16. Silk JB, Altmann J, Alberts SC. Social relationships among adult female baboons (Papio cyncephalus) I. Variation in the strength of social bonds.. Behav Ecol Sociobiol 2006;61:183–195.
      17. Silk JB, Alberts SC, Altmann J. Social relationships among adult female baboons (Papio cyncephalus). II. Variation in the quality and stability of social bonds.. Behav Ecol Sociobiol 2006;61:197–204.
      18. Lehmann J, Boesch C. Sexual Differences in Chimpanzee Sociality.. Int J Primatol 2008 Feb;29(1):65-81.
        pmc: PMC2758377pubmed: 19816541doi: 10.1007/s10764-007-9230-9google scholar: lookup
      19. Swedell L. Affiliation among females in wild Hamadryas baboons (Papio hamadryas hamadryas). Int J Primatol 2002;23:1205–1226.
      20. Linklater WL, Cameron EZ. Social dispersal but with philopatry reveals incest avoidance in a polygynous ungulate.. Anim Behav 2009;77:1085–1093.
      21. Linklater WL, Cameron EZ. Tests for cooperative behaviour between stallions.. Anim Behav 2000 Dec;60(6):731-743.
        pubmed: 11124871doi: 10.1006/anbe.2000.1525google scholar: lookup
      22. Feh C. Alliances and reproductive success in Camargue stallions.. Anim Behav 1999 Mar;57(3):705-713.
        pubmed: 10196062doi: 10.1006/anbe.1998.1009google scholar: lookup
      23. Linklater WL. Adaptive explanation in socio-ecology: lessons from the Equidae.. Biol Rev Camb Philos Soc 2000 Feb;75(1):1-20.
        pubmed: 10740891doi: 10.1017/s0006323199005411google scholar: lookup
      24. Monard A-M, Duncan P, Boy V. The proximate mechanisms of natal dispersal in female horses.. Behaviour 1996;133:1095–1124.
      25. Linklater WL, Cameron EZ, Stafford KJ, Veltman CJ. Social and spatial structure and range use by Kaimanawa wild horses (Equus caballus: Equidae). N Z J Ecol 2000;24:139–152.
      26. Proops L, McComb K, Reby D. Cross-modal individual recognition in domestic horses (Equus caballus).. Proc Natl Acad Sci U S A 2009 Jan 20;106(3):947-51.
        pmc: PMC2630083pubmed: 19075246doi: 10.1073/pnas.0809127105google scholar: lookup
      27. Waring GH. Horse Behavior.. 2nd Ed. New York: Noyes Publications; 2002.
      28. van Dierdendock M, Goodwin D. In: The Human-Animal Relationship – Forever and a Day. de Jonge F, van den Bos R, editors. Assen, Netherlands: van Gorcum; 2005. pp. 65–81.
      29. Kimura R. Mutual grooming and preferred associate relationships in a band of free-ranging horses.. Appl Anim Behav Sci 1998;59:253–263.
      30. Sigurjónsdóttir H, van Dierendonck MC, Snorrason S, Thórhallsdóttir AG. Social relationships in a group of horses without a mature stallion.. Behaviour 2003;140:783–804.
      31. Heitor F, do Mar Oom M, Vicente L. Social relationships in a herd of Sorraia horses Part II. Factors affecting affiliative relationships and sexual behaviours.. Behav Processes 2006 Nov 1;73(3):231-9.
        pubmed: 16828984doi: 10.1016/j.beproc.2006.05.005google scholar: lookup
      32. Cameron EZ, Linklater WL, Stafford KJ, Minot EO. Aging and improving reproductive success in horses: Declining residual reproductive value or just older and wiser?. Behav Ecol Sociobiol 2000;47:243–249.
      33. Cameron EZ, Linklater WL, Stafford KJ, Minot EO. Social group and maternal behaviour in feral horses, Equus caballus.. Behav Ecol Sociobiol 2003;53:92–101.
      34. Pluhácek J, Bartos L. Male infanticide in captive plains zebra, Equus burchelli.. Anim Behav 2000 Apr;59(4):689-694.
        pubmed: 10792924doi: 10.1006/anbe.1999.1371google scholar: lookup
      35. Ryder O, Massena R. A case of male infanticide in Equus przewalskii.. Appl Anim Behav Sci 1988;21:187–190.
      36. Duncan P. Foal killing by stallions.. Appl Anim Ethol 1982;8:567–570.
      37. Gray ME. An infanticide attempt by a free-roaming feral stallion (Equus caballus).. Biol Lett 2009 Feb 23;5(1):23-5.
        pmc: PMC2657763pubmed: 19019779doi: 10.1098/rsbl.2008.0571google scholar: lookup
      38. Silk JB, Beehner JC, Bergman TJ, Crockford C, Engh AL, Moscovice LR, Wittig RM, Seyfarth RM, Cheney DL. The benefits of social capital: close social bonds among female baboons enhance offspring survival.. Proc Biol Sci 2009 Sep 7;276(1670):3099-104.
        pmc: PMC2817129pubmed: 19515668doi: 10.1098/rspb.2009.0681google scholar: lookup
      39. Galimberti F, Boitani L, Marzetti I. The frequency and costs of harassment in southern elephant seals.. Ethol Ecol Evol 2000;12:345–365.
      40. Nefdt RJC. Disruptions of matings, harassment and lek-breeding in Kafue lechwe antelope.. Anim Behav 1995;49:419–429.
      41. DeVries AC, Glasper ER, Detillion CE. Social modulation of stress responses.. Physiol Behav 2003 Aug;79(3):399-407.
        pubmed: 12954434doi: 10.1016/s0031-9384(03)00152-5google scholar: lookup
      42. House JS, Landis KR, Umberson D. Social relationships and health.. Science 1988 Jul 29;241(4865):540-5.
        pubmed: 3399889doi: 10.1126/science.3399889google scholar: lookup
      43. Sachser N, Dürschlag M, Hirzel D. Social relationships and the management of stress.. Psychoneuroendocrinology 1998 Nov;23(8):891-904.
        pubmed: 9924743doi: 10.1016/s0306-4530(98)00059-6google scholar: lookup
      44. Shier DM. Effect of family support on the success of translocated black-tailed prairie dogs.. Conserv Biol 2006 Dec;20(6):1780-90.
        pubmed: 17181813doi: 10.1111/j.1523-1739.2006.00512.xgoogle scholar: lookup
      45. Langergraber KE, Mitani JC, Vigilant L. The limited impact of kinship on cooperation in wild chimpanzees.. Proc Natl Acad Sci U S A 2007 May 8;104(19):7786-90.
        pmc: PMC1876525pubmed: 17456600doi: 10.1073/pnas.0611449104google scholar: lookup
      46. Clutton-Brock TH, Russell AF, Sharpe LL, Brotherton PN, McIlrath GM, White S, Cameron EZ. Effects of helpers on juvenile development and survival in meerkats.. Science 2001 Sep 28;293(5539):2446-9.
        pubmed: 11577235doi: 10.1126/science.1061274google scholar: lookup
      47. Clutton-Brock TH, O'Riain MJ, Brotherton PN, Gaynor D, Kansky R, Griffin AS, Manser M. Selfish sentinels in cooperative mammals.. Science 1999 Jun 4;284(5420):1640-4.
        pubmed: 10356387doi: 10.1126/science.284.5420.1640google scholar: lookup
      48. Cole KM, Gawlinski A, Steers N, Kotlerman J. Animal-assisted therapy in patients hospitalized with heart failure.. Am J Crit Care 2007 Nov;16(6):575-85; quiz 586; discussion 587-8.
        pubmed: 17962502
      49. Cameron EZ, Linklater WL. Extreme sex ratio variation in relation to change in condition around conception.. Biol Lett 2007 Aug 22;3(4):395-7.
        pmc: PMC2390657pubmed: 17439844doi: 10.1098/rsbl.2007.0089google scholar: lookup
      50. Tutt JFD. In: Veterinary Notes for Horse Owners. Hayes MH, editor. London: Stanley Paul; 1968. pp. 512–526.
      51. Richardson JD, Cripps PJ, Lane JG. An evaluation of the accuracy of ageing horses by their dentition: can a computer model be accurate?. Vet Rec 1995 Aug 5;137(6):139-40.
        pubmed: 8540206doi: 10.1136/vr.137.6.139google scholar: lookup
      52. Cameron EZ, Linklater WL. Individual mares bias investment in sons and daughters in relation to their condition.. Anim Behav 2000 Sep;60(3):359-367.
        pubmed: 11007645doi: 10.1006/anbe.2000.1480google scholar: lookup
      53. Berger J. Wild Horses of the Great Basin. Chicago: Univ of Chicago; 1986.
      54. Altmann J. Observational study of behavior: sampling methods.. Behaviour 1974;49(3):227-67.
        pubmed: 4597405doi: 10.1163/156853974x00534google scholar: lookup
      55. Sapolsky RM, Alberts SC, Altmann J. Hypercortisolism associated with social subordinance or social isolation among wild baboons.. Arch Gen Psychiatry 1997 Dec;54(12):1137-43.
        pubmed: 9400351doi: 10.1001/archpsyc.1997.01830240097014google scholar: lookup

      Citations

      This article has been cited 149 times.
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