Helping effort increases with relatedness in bell miners, but 'unrelated' helpers of both sexes still provide substantial care

Jonathan Wright, Paul G. McDonald, Luc Te Marvelde, Anahita J N Kazem, Charles M. Bishop

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Indirect fitness benefits from kin selection can explain why non-breeding individuals help raise the young of relatives. However, the evolution of helping by non-relatives requires direct fitness benefits, for example via group augmentation. Here, we examine nest visit rates, load sizes and prey types delivered by breeding pairs and their helpers in the cooperatively breeding bell miner (Manorina melanophrys). In this system, males remain in their natal colony while young females typically disperse, and helpers of both sexes often assist at multiple nests concurrently. We found extremely clear evidence for the expected effect of genetic relatedness on individual helping effort per nest within colonies. This positive incremental effect of kinship was facultative-i.e. largely the result of within-individual variation in helping effort. Surprisingly, no sex differences were detectable in any aspect of helping, and even non-relatives provided substantial aid. Helpers and breeders of both sexes regulated their provisioning effort by responding visit-by-visit to changes in nestling begging. Helping behaviour in bell miners therefore appears consistent with adaptive cooperative investment in the brood, and kin-selected care by relatives. Similar investment by 'unrelated' helpers of both sexes argues against direct fitness benefits, but is perhaps explained by kin selection at the colony level.

LanguageEnglish
Pages437-445
Number of pages9
JournalProceedings of the Royal Society B: Biological Sciences
Volume277
Issue number1680
DOIs
Publication statusPublished - 7 Feb 2010

Fingerprint

Miners
relatedness
kin selection
nest
fitness
nests
Breeding
gender
Helping Behavior
helping behavior
breeding
kinship
individual variation
nestling
gender differences
Sex Characteristics
cooperatives
genetic relationships
aid
effect

Keywords

  • Brood demand
  • Helping-at-the-nest
  • Kinship
  • Load size
  • Natal philopatry
  • Nest visit rate

Cite this

Wright, Jonathan ; McDonald, Paul G. ; Te Marvelde, Luc ; Kazem, Anahita J N ; Bishop, Charles M. / Helping effort increases with relatedness in bell miners, but 'unrelated' helpers of both sexes still provide substantial care. In: Proceedings of the Royal Society B: Biological Sciences. 2010 ; Vol. 277, No. 1680. pp. 437-445.
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Helping effort increases with relatedness in bell miners, but 'unrelated' helpers of both sexes still provide substantial care. / Wright, Jonathan; McDonald, Paul G.; Te Marvelde, Luc; Kazem, Anahita J N; Bishop, Charles M.

In: Proceedings of the Royal Society B: Biological Sciences, Vol. 277, No. 1680, 07.02.2010, p. 437-445.

Research output: Contribution to journalArticleResearchpeer-review

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