Variation in parent-offspring kinship in socially monogamous systems with extra-pair reproduction and inbreeding

Jane M. Reid, Greta Bocedi, Pirmin Nietlisbach, A. Bradley Duthie, Matthew E. Wolak, Elizabeth A. Gow, Peter Arcese

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)
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Female extra-pair reproduction in socially monogamous systems is predicted to cause cuckolded socially-paired males to conditionally reduce paternal care, causing selection against extra-pair reproduction and underlying polyandry. However, existing models and empirical studies have not explicitly considered that cuckolded males might be related to their socially-paired female and/or to her extra-pair mate, and therefore be related to extra-pair offspring that they did not sire but could rear. Selection against paternal care, and hence against extra-pair reproduction, might then be weakened. We derive metrics that quantify allele-sharing between within-pair and extra-pair offspring and their mother and her socially-paired male in terms of coefficients of kinship and inbreeding. We use song sparrow (Melospiza melodia) paternity and pedigree data to quantify these metrics, and thereby quantify the joint effects of extra-pair reproduction and inbreeding on a brood's total allelic value to its socially-paired parents. Cuckolded male song sparrows were almost always detectably related to extra-pair offspring they reared. Consequently, although brood allelic value decreased substantially following female extra-pair reproduction, this decrease was reduced by within-pair and extra-pair reproduction among relatives. Such complex variation in kinship within nuclear families should be incorporated into models considering coevolutionary dynamics of extra-pair reproduction, parental care, and inbreeding.
Original languageEnglish
Pages (from-to)1512-1529
Number of pages18
Issue number7
Early online date1 Jun 2016
Publication statusPublished - Jul 2016

Bibliographical note

We thank the Tsawout and Tseycum First Nations bands for allowing access to Mandarte; everyone who contributed to long-term data collection; Lukas Keller and Ryan Germain for helpful discussions; and the European Research Council, UK Royal Society, National Sciences and Engineering Research Council of Canada and Swiss National Science Foundation for their invaluable support.

Data are available from the Dryad Digital Repository:


  • cuckoldry
  • paternal investment
  • paternity
  • pedigree
  • polyandry
  • relatedness
  • sexual conflict


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