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An obligate brood parasite trapped in the intraspecific arms race of its hosts


Reciprocal selection pressures often lead to close and adaptive matching of traits in coevolved species. A failure of one species to match the evolutionary trajectories of another is often attributed to evolutionary lags1,2 or to differing selection pressures across a geographic mosaic3,4. Here we show that mismatches in adaptation of interacting species—an obligate brood parasitic duck and each of its two main hosts—are best explained by the evolutionary dynamics within the host species. Rejection of the brood parasite's eggs was common by both hosts, despite a lack of detectable cost of parasitism to the hosts. Egg rejection markedly reduced parasite fitness, but egg mimicry experiments revealed no phenotypic natural selection for more mimetic parasitic eggs. These paradoxical results were resolved by the discovery of intraspecific brood parasitism and conspecific egg rejection within the hosts themselves. The apparent arms race between species seems instead to be an incidental by-product of within-species conflict, with little recourse for evolutionary response by the parasite.

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Figure 1: Frequency and attributes of parasitism in the two main hosts of the black-headed duck, the red-gartered coot (RG coot) and red-fronted coot (RF coot).
Figure 2: Results of egg mimicry experiments in the two principal hosts.

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  1. Rothstein, S. I. A model system for coevolution: avian brood parasitism. Annu. Rev. Ecol. Syst. 21, 481–508 (1990)

    Article  Google Scholar 

  2. Davies, N. B. Cuckoos, Cowbirds and Other Cheats (Poyser, London, 2000)

    Google Scholar 

  3. Thompson, J. N. The evolution of species interactions. Science 284, 2116–2118 (1999)

    Article  CAS  Google Scholar 

  4. Thompson, J. N., Nuismer, S. L. & Gomulkiewicz, R. Coevolution and maladaptation. Integ. Comp. Biol. 42, 381–387 (2002)

    Article  Google Scholar 

  5. Brooke, M. de L. & Davies, N. B. Egg mimicry by cuckoos Cuculus canorus in relation to discrimination by hosts. Nature 335, 630–632 (1988)

    Article  ADS  Google Scholar 

  6. Marchetti, K., Nakamura, H. & Gibbs, H. L. Host-race formation in the common cuckoo. Science 282, 471–472 (1998)

    Article  ADS  CAS  Google Scholar 

  7. Gibbs, H. L., Sorenson, M. D., Marchetti, K., Brooke, M. de L., Davies, N. B. & Nakamura, H. Genetic evidence for female host-specific races in the common cuckoo. Nature 407, 183–186 (2000)

    Article  ADS  CAS  Google Scholar 

  8. Payne, R. B. The ecology of brood parasitism in birds. Annu. Rev. Ecol. Syst. 8, 1–28 (1977)

    Article  ADS  Google Scholar 

  9. Lyon, B. E. & Eadie, J. M. Mode of development and interspecific avian brood parasitism. Behav. Ecol. 2, 309–318 (1991)

    Article  Google Scholar 

  10. Weller, M. W. The breeding biology of the parasitic black-headed duck. Living Bird 7, 169–208 (1968)

    Google Scholar 

  11. Sorenson, M. D. Effects of intra- and interspecific brood parasitism on a precocial host, the canvasback, Aythya valisinaria. Behav. Ecol. 8, 153–161 (1997)

    Article  Google Scholar 

  12. Mason, P. & Rothstein, S. I. Crypsis versus mimicry and the color of shiny cowbird eggs. Am. Nat. 130, 161–167 (1987)

    Article  Google Scholar 

  13. Roskaft, E., Orians, G. H. & Beletsky, L. D. Why do red-winged blackbirds accept eggs of brown-headed blackbirds? Evol. Ecol. 4, 35–42 (1990)

    Article  Google Scholar 

  14. Thomson, D. L., Monaghan, P. & Furness, R. W. The demands of incubation and avian clutch size. Biol. Rev. 73, 293–304 (1998)

    Article  Google Scholar 

  15. Arnold, T. W. Food Limitation and the Adaptive Significance of Clutch Size in American Coots (Fulica americana) Thesis, Univ. Western Ontario (1990)

    Google Scholar 

  16. Freeman, S. Egg variability and conspecific brood parasitism in the Ploceus weaverbirds. Ostrich 59, 49–53 (1988)

    Article  Google Scholar 

  17. Jackson, W. M. in Parasitic Birds and their Hosts (eds Rothstein, S. I. & Robinson, S. K.) 407–416 (Oxford University, New York, 1998)

    Google Scholar 

  18. Lahti, D. C. & Lahti, A. R. How precise is egg discrimination in weaverbirds? Anim. Behav. 62, 1135–1142 (2002)

    Article  Google Scholar 

  19. Lyon, B. E. Egg recognition and counting reduce costs of avian conspecific brood parasitism. Nature 422, 495–499 (2003)

    Article  ADS  CAS  Google Scholar 

  20. Jamieson, I. G., McRae, S. B., Simmons, R. E. & Trewby, M. High rates of conspecific brood parasitism and egg rejection in coots and moorhens in ephemeral wetlands in Namibia. Auk 117, 250–255 (2000)

    Article  Google Scholar 

  21. Sorenson, M. D. Evidence of conspecific nest parasitism and egg discrimination in the sora. Condor 97, 819–821 (1995)

    Article  Google Scholar 

  22. Lyon, B. E., Eadie, J. McA. & Hamilton, L. D. Parental preference selects for ornamental plumage in American coot chicks. Nature 371, 240–243 (1994)

    Article  ADS  Google Scholar 

  23. Todd, F. S. Natural History of the Waterfowl (Ibis Publishing, San Diego, 1996)

    Google Scholar 

  24. Weller, M. W. Experimental parasitism of American coot nests. Auk 88, 108–115 (1971)

    Article  Google Scholar 

  25. Lotem, A., Nakamura, H. & Zahavi, A. Rejection of cuckoo eggs in relation to host age: a possible evolutionary equilibrium. Behav. Ecol. 3, 128–132 (1992)

    Article  Google Scholar 

  26. Lotem, A. Learning to recognize cuckoo nestlings is maladaptive to cuckoo Culculus canoris hosts. Nature 362, 743–745 (1993)

    Article  ADS  Google Scholar 

  27. Davies, N. B., Brooke, M. de L. & Kacelnik, A. Recognition errors and probability of parasitism determines whether reed warblers should accept or reject mimetic cuckoo eggs. Proc. R. Soc. Lond. B 263, 925–931 (1996)

    Article  ADS  Google Scholar 

  28. Frederick, P. C. & Shields, M. A. Corrections for the underestimation of brood parasitism frequency derived from daily nest inspections. J. Field Ornithol. 57, 224–226 (1986)

    Google Scholar 

  29. Lyon, B. E. Tactics of parasitic American coots: host choice and the pattern of egg dispersion among host nests. Behav. Ecol. Sociobiol. 33, 87–100 (1993)

    Article  Google Scholar 

  30. McRae, S. B. Identifying eggs of conspecific brood parasites in the field: a cautionary note. Ibis (Lond. 1859) 139, 701–704 (1997)

    Google Scholar 

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We thank C. Benkman, J. Briskie, A. Chaine, N. Davies, M. Hauber, A. Lotem, D. Mock, R. Montgomerie, S. Rothstein, J. Thompson and K. Wasson for comments on the manuscript; the National Geographic Society and the British Broadcasting Corporation (D. Attenborough's Life of Birds) for funding; the Flores family, J. Echerran, M. Beade and J. C. Reboreda for logistic support; and V. Meuhter, G. Goggin and A. Carminati for assistance in the field. During part of the study, B.E.L. was supported by the Kananaskis Field Stations of the University of Calgary and University of California, and J.McA.E. by the Dennis G. Raveling Endowment.

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Correspondence to Bruce E. Lyon.

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Lyon, B., Eadie, J. An obligate brood parasite trapped in the intraspecific arms race of its hosts. Nature 432, 390–393 (2004).

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