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Multiple benefits of cooperative breeding in purple-crowned fairy-wrens: a consequence of fidelity?
Article first published online: 28 APR 2010
DOI: 10.1111/j.1365-2656.2010.01697.x
© 2010 The Authors. Journal compilation © 2010 British Ecological Society
Additional Information
How to Cite
Kingma, S. A., Hall, M. L., 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. doi: 10.1111/j.1365-2656.2010.01697.x
Publication History
- Issue published online: 7 JUN 2010
- Article first published online: 28 APR 2010
- Received 19 October 2009; accepted 16 March 2010 Handling Editor: John Quinn
Keywords:
- communal breeding;
- delayed dispersal;
- helpers-at-the-nest;
- kin-selection;
- mixed model;
- parental investment;
- philopatry;
- promiscuity
Summary
1. Kin selection is one of the mechanisms that can explain apparent altruism by subordinate individuals in cooperatively breeding species, if subordinates boost the production of kin. We compared productivity and breeder survival in pairs with and without subordinates in a genetically monogamous cooperatively breeding bird, the purple-crowned fairy-wren Malurus coronatus.
2. Additive effects of subordinate help increased productivity. Total feeding rates to the nest were increased by two or more subordinates, and fledgling production was greater in larger groups. Not all subordinates contributed to nestling feeding, and the effect of group size was greater when non-contributors were excluded from analyses, suggesting that increased fledgling production was a direct result of help.
3. Compensatory effects of subordinate help improved breeder survival. Assisted breeders reduced their workload by 20–30%, irrespective of the number of helpers. Although re-nesting intervals were not affected by group size, reduced breeder feeding rates resulted in improved survival and breeders in larger groups survived better.
4. Subordinates and nestlings are usually progeny of the breeding pair in this species, and benefits of cooperative breeding are very different from three congeners with extremely high levels of extra-group paternity (EGP). In these Malurus, fledgling production and survival of male breeders are not enhanced in larger groups. This is consistent with the expectation that kin-selected benefits vary with relatedness, and thus levels of EGP.
5. We tested whether benefits of cooperative breeding in 37 avian species varied with levels of extra-group mating. Both direct and phylogenetically controlled comparisons showed that improvement of (male) breeder survival and enhanced productivity are more likely when fidelity is higher, as predicted when investment of subordinates correlates with relatedness to offspring. This pattern highlights the importance of considering the genetic mating system for understanding the evolution of cooperative breeding.