The Evolution of Cooperative Breeding in Vertebrates


Cooperative breeding – in which some sexually mature individuals forgo independent breeding, join a group as subordinate and help to raise the offspring of others – occurs in at least 3% (mammals) and 9% (birds) of vertebrates. Because helping others is costly, this behaviour contradicts the concept of ‘selfish’ natural selection. The intriguing evolutionary paradox of such seemingly altruistic behaviour has, therefore, been the focus of much study aiming to unravelling the evolutionary drivers underlying cooperative breeding. The benefits of group living, costs of dispersal and constraints of limited available independent breeding positions may persuade individuals to delay independent breeding and remain as subordinates within a group. However, it is the range of subsequent benefits (indirect benefits – such as improving reproduction and survival of related individuals or direct benefits – such as gaining breeding experience, benefits of future cooperation with raised recruits or gaining a share in reproduction) that favour the evolution of helping.

Key Concepts

  • The evolution of cooperative breeding is best understood by considering the benefits for helpers obtained from delayed dispersal and from helping, and the benefits helpers impose on breeders.
  • Subordinate individuals are expected to stay when there are constraints on independent breeding and/or when they obtain benefits in their resident territory.
  • Subordinates individuals can help related individuals and gain indirect (kin selected) fitness benefits, but in many species, helpers can also be unrelated; direct benefits of helping (like parentage, being allowed to stay) may thus be more important than commonly assumed.
  • Breeders can benefit from helpers, either because these improve their reproductive success or because breeders can reduce their own investment in the offspring.
  • The surplus of reproductive capable individuals and the effects of helpers on survival and reproduction can have important implications for population dynamics in cooperatively breeding species.

Keywords: cooperative breeding; helping behaviour; direct fitness benefits; indirect fitness benefits; costs of helping; group stability; population dynamics; relatedness

Figure 1. Four species used in long‐term studies investigating the evolution of cooperative breeding in vertebrates: (a) Lake Tanganyika cichlid (Neolamprologus pulcher). A breeding group defending their territory against a predatory fish. Reproduced with permission from M. Taborsky; (b) superb fairy‐wren (Malurus cyaneus). A dominant male. Reproduced with permission from A. Russell; (c) meerkat (Suricata suricatta). Subordinates help babysit the dominant pairs' offspring. Reproduced with permission from A.J. Young; (d) naked mole rat (Heterocephalus glaber), living in groups that may contain up to hundreds of helpers. Reproduced with permission from Lorna Ellen Faulkes.
Figure 2. Examples of the percentage of group offspring that is sired by male and female subordinates in populations of cooperatively breeding vertebrates. Most of these offspring are sired by a subordinate within the group, but sometimes subordinates, usually males, gain parentage outside the own group. Although in some species, subordinates refrain (almost) completely from direct reproduction, in other species, they produce nearly as many offspring as the dominants in the group [e.g. pukeko (Porphyrio porphyrioi melanotus)]. Furthermore, in some species, subordinates of one sex produce a considerably larger part of group offspring than the other sex (note that in some species,e.g. superb fairy‐wrens and write‐browed scrubwrens, no values were given for females because subordinates in these species are exclusively males). In all cases, parentage was assigned using molecular analyses. The extent to which reproduction is divided between same‐sex individuals within each group is termed ‘reproductive skew’ and the ecological drivers of this variation have been subject to extensive study (not addressed here, but see Trubenová and Hager, for an extensive review). Species and sources: A, dwarf mongoose (Helogale parvula, Keane et al., ); B, wild dog (Lycaon pictus, Girman et al., ); C, meerkat (Suricata suricatta, Griffin et al., ); D, Lake Tanganyika cichlid (Neolamprologus pulcher, Dierkes et al., ); E, Lake Tanganyika cichlid (Julidochromis ornatus, Awata et al., ); F, Seychelles warbler (Acrocephalus sechellensis, Richardson et al., ); G, moorhen (Gallinula chloropus, McRae, ); H, Florida scrub‐jay (Aphelocoma coerulescens, Quinn et al., ); I, white‐browed scrubwren (Sericornis frontalis, Whittingham et al., ); J, Alpine accentor (Prunella collaris, Hartley et al., ); K, pukeko (Lambert et al., ); L, white‐throated magpie‐jay (Calocitta formosa, Berg, ); M, long‐tailed tit (Aegithalos caudatus, Hatchwell et al., ); N, superb fairy‐wren (Malurus cyaneus, Double and Cockburn, ); O, American crow (Corvus brachyrhynchos, Townsend et al., ) and P, ground tit (Parus humilis, Wang and Lu, ). Q, red‐winged fairy‐wren (Malurus elegans, Brouwer et al., ).


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Further Reading

Brown JL (1987) Helping and Communal Breeding in Birds. Princeton, NJ: Princeton University Press.

Clutton‐Brock TH (2002) Breeding together: kin selection and mutualism in cooperative vertebrates. Science 296: 69–72.

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Hatchwell BJ (2009) The evolution of cooperative breeding in birds: kinship, dispersal and life history. Philosophical Transactions of the Royal Society B‐Biological Sciences 364: 3217–3227.

Kingma SA, Hall ML, Arriero E and Peters A (2010) Multiple benefits of cooperative breeding in purple‐crowned fairy‐wrens: a consequence of fidelity? Journal of Animal Ecology 79: 757–768.

Koenig WD and Dickinson JL (eds) (2004) Ecology and Evolution of Cooperative Breeding in Birds. Cambridge, MA: Cambridge University Press.

Koenig WD and Dickinson JL (eds) (2016) Cooperative Breeding in Vertebrates: Studies of Ecology, Evolution,and Behavior. Cambridge, MA: Cambridge University Press.

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Komdeur, Jan, Richardson, David S, Hammers, Martijn, Eikenaar, Cas, Brouwer, Lyanne, and Kingma, Sjouke A(Apr 2017) The Evolution of Cooperative Breeding in Vertebrates. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0021218.pub2]