Testing Hamilton's rule with competition between relatives


Hamilton’s1,2 theory of kin selection suggests that individuals should show less aggression, and more altruism, towards closer kin. Recent theoretical work has, however, suggested that competition between relatives can counteract kin selection for altruism3,4,5,6,7,8,9,10,11. Unfortunately, factors that tend to increase the average relatedness of interacting individuals—such as limited dispersal—also tend to increase the amount of competition between relatives. Therefore, in most natural systems, the conflicting influences of increased competition and increased relatedness are confounded, limiting attempts to test theory4,8,9,10. Fig wasp taxa exhibit varying levels of aggression among non-dispersing males that show a range of average relatedness levels. Thus, across species, the effects of relatedness and competition between relatives can be separated. Here we report that—contrary to Hamilton's original prediction1,2,12 but in agreement with recent theory5,6,7,8,9,10,11—the level of fighting between males shows no correlation with the estimated relatedness of interacting males, but is negatively correlated with future mating opportunities.

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Figure 1: Mean injury level contrasts plotted against estimated relatedness contrasts.
Figure 2: Mean injury level (LEI) contrasts plotted against the mean number of females developing in a fruit (log10 transformed) contrasts.
Figure 3: Hamilton's rule with relatedness and competition between relatives.


  1. 1

    Hamilton, W. D. The evolution of altruistic behaviour. Am. Nat. 97, 354–356 (1963).

    Article  Google Scholar 

  2. 2

    Hamilton, W. D. The genetical evolution of social behaviour, I & II. J. Theor. Biol. 7, 1–52 ( 1964).

    CAS  Article  Google Scholar 

  3. 3

    Grafen, A. in Behavioural Ecology: An Evolutionary Approach (eds Krebs, J. R. & Davies, N. B.) 62–84 (Blackwell Scientific, Oxford, 1984).

    Google Scholar 

  4. 4

    Murray, M. G. & Gerrard, R. J. Conflict in the neighbourhood: models where close relatives are in direct competition. J. Theor. Biol. 111, 237–246 ( 1984).

    MathSciNet  Article  Google Scholar 

  5. 5

    Wilson, D. S., Pollock, G. B. & Dugatkin, L. A. Can altruism evolve in purely viscous populations. Evol. Ecol. 6, 331–341 (1992).

    Article  Google Scholar 

  6. 6

    Taylor, P. D. Altruism in viscous populations—an inclusive fitness model. Evol. Ecol. 6, 352–356 ( 1992).

    Article  Google Scholar 

  7. 7

    Taylor, P. D. Inclusive fitness in a homogeneous environment. Proc. R. Soc. Lond. B 249, 299–302 ( 1992).

    ADS  Article  Google Scholar 

  8. 8

    Queller, D. C. Does population viscosity promote kin selection? Trends Ecol. Evol. 7, 322–324 ( 1992).

    CAS  Article  Google Scholar 

  9. 9

    Queller, D. C. Genetic relatedness in viscous populations. Evol. Ecol. 8, 70–73 (1994).

    Article  Google Scholar 

  10. 10

    Frank, S. A. Foundations of Social Evolution (Princeton Univ. Press, Princeton, 1998).

    Google Scholar 

  11. 11

    Kelly, J. K. The effect of scale dependent processes on kin selection: mating and density regulation. Theor. Popul. Biol. 46, 32– 57 (1994).

    CAS  Article  Google Scholar 

  12. 12

    Hamilton, W. D. in Reproductive Competition and Sexual Selection in Insects (eds Blum, M. S. & Blum, N. A.) 167–220 (Academic, New York, 1979).

    Google Scholar 

  13. 13

    Murray, M. G. The closed environment of the fig receptacle and its influence on male conflict in the Old World fig wasp, Philotrypesis pilosa. Anim. Behav. 35, 488–506 ( 1987).

    Article  Google Scholar 

  14. 14

    Murray, M. G. Environmental constraints on fighting in flightless male fig wasps. Anim. Behav. 38, 186–193 (1989).

    Article  Google Scholar 

  15. 15

    Herre, E. A. et al. in Social Competition and Cooperation in Insects and Arachnids Vol. I, The Evolution of Mating Systems (eds Choe, J. & Crespi, B. ) 226–239 (Princeton Univ. Press, Princeton, 1997).

    Google Scholar 

  16. 16

    West, S. A. & Herre, E. A. Partial local mate competition and the sex ratio: a study on non-pollinating fig wasps. J. Evol. Biol. 11, 531–548 ( 1998).

    Article  Google Scholar 

  17. 17

    Enquist, M. & Leimar, O. The evolution of fatal fighting. Anim. Behav. 39, 1–9 (1990).

    Article  Google Scholar 

  18. 18

    Vincent, S. L. Polymorphism and Fighting in Male Fig Wasps. Thesis, Rhodes Univ. (1991).

    Google Scholar 

  19. 19

    Harvey, P. H. & Pagel, M. D. The Comparative Method in Evolutionary Biology (Oxford Univ. Press, Oxford, 1991).

    Google Scholar 

  20. 20

    CluttonBrock, T. H. et al. Individual contributions to babysitting in a cooperative mongoose, Suricata suricatta. Proc. R. Soc. Lond. B 267, 301–305 (2000).

    CAS  Article  Google Scholar 

  21. 21

    Carcamo, H. A. & Spence, J. R. Kin discrimination and cannibalism in water striders (Heteroptera: Gerridae): another look. Oikos 70, 412–416 ( 1994).

    Article  Google Scholar 

  22. 22

    Dunn, P. O., Cockburn, A. & Mulder, R. A. Fairy-wren helpers often care for young to which they are unrelated. Proc. R. Soc. Lond. B 259, 339–343 (1995).

    ADS  Article  Google Scholar 

  23. 23

    Magrath, R. D. & Whittingham, L. A. Subordinate males are more likely to help if unrelated to the breeding female in cooperatively breeding white-browed scrubwrens. Behav. Ecol. Sociobiol. 41, 185–192 (1997).

    Article  Google Scholar 

  24. 24

    CluttonBrock, T. H. et al. Selfish sentinels in cooperative mammals. Science 284, 1640–1644 ( 1999).

    ADS  CAS  Article  Google Scholar 

  25. 25

    Read, A. F., Anwar, M., Shutler, D. & Nee, S. Sex allocation and population structure in malaria and related parasitic protozoa. Proc. R. Soc. Lond. B. 260, 359–363 (1995).

    ADS  CAS  Article  Google Scholar 

  26. 26

    West, S. A., Smith T. G. & Read, A. F. Sex allocation and population structure in apicomplexan (protozoa) parasites. Proc. R. Soc. Lond. B. 267, 257– 263 (2000).

    CAS  Article  Google Scholar 

  27. 27

    Machado, C. A., Herre, E. A., McCafferty, S. & Bermingham, E. Molecular phylogenies of fig pollinating and non-pollinating wasps and the implications for the origin and evolution of the fig–fig wasp mutualism. J. Biogeogr. 23, 531–542 (1996).

    Article  Google Scholar 

  28. 28

    Machado, C. A. Molecular Natural History of Fig Wasps. Thesis, Univ. California (1998).

    Google Scholar 

  29. 29

    Yang, Z. Estimating the pattern of nucleotide substitution. J. Mol. Evol. 39, 105–111 ( 1994).

    ADS  PubMed  Google Scholar 

  30. 30

    Purvis, A. & Rambaut, A. Comparative analysis by independent contrasts (CAIC): an Apple Macintosh application for analysing comparative data. Comput. Applics Biosci. 11, 247– 251 (1995).

    CAS  Google Scholar 

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We thank S. Frank, S. Nee, S. Reece and R. Trivers for comments that improved the clarity of our manuscript. This work was supported by the BBSRC, STRI and NERC.

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Correspondence to Stuart A. West.

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West, S., Murray, M., Machado, C. et al. Testing Hamilton's rule with competition between relatives. Nature 409, 510–513 (2001). https://doi.org/10.1038/35054057

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