Testing the predictions of sex allocation hypotheses in dimporphic, cooperatively breeding riflemen

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dc.contributor.authorKhwaja N
dc.contributor.authorPreston SAJ
dc.contributor.authorBriskie JV
dc.contributor.authorHatchwell BJ
dc.date.accessioned2018-11-18T22:58:57Z
dc.date.available2018-11-18T22:58:57Z
dc.date.issued2018en
dc.date.updated2018-10-31T19:43:25Z
dc.description.abstract© 2018 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. Evolutionary theory predicts that parents should invest equally in the two sexes. If one sex is more costly, a production bias is predicted in favour of the other. Two well-studied causes of differential costs are size dimorphism, in which the larger sex should be more costly, and sex-biased helping in cooperative breeders, in which the more helpful sex should be less costly because future helping “repays” some of its parents’ investment. We studied a bird species in which both processes should favor production of males. Female riflemen Acanthisitta chloris are larger than males, and we documented greater provisioning effort in more female-biased broods indicating they are likely costlier to raise. Riflemen are also cooperative breeders, and males provide more help than females. Contrary to expectations, we observed no male bias in brood sex ratios, which did not differ significantly from parity. We tested whether the lack of a population-wide pattern was a result of facultative sex allocation by individual females, but this hypothesis was not supported either. Our results show an absence of adaptive patterns despite a clear directional hypothesis derived from theory. This appears to be associated with a suboptimal female-biased investment ratio. We conclude that predictions of adaptive sex allocation may falter because of mechanistic constraint, unrecognized costs and benefits, or weak selection.en
dc.identifier.doihttps://doi.org/10.1002/ece3.3934
dc.identifier.issn2045-7758
dc.identifier.issn2045-7758
dc.identifier.urihttp://hdl.handle.net/10092/16227
dc.languageEnglish
dc.language.isoen
dc.rightsThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2018 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.en
dc.subjectAcanthisittidaeen
dc.subjectcooperative breedingen
dc.subjectparental careen
dc.subjectprovisioning rateen
dc.subjectrepayment hypothesisen
dc.subjectriflemanen
dc.subjectsex ratioen
dc.subjectsexual dimorphismen
dc.subject.anzsrcFields of Research::31 - Biological sciences::3104 - Evolutionary biology::310410 - Phylogeny and comparative analysisen
dc.titleTesting the predictions of sex allocation hypotheses in dimporphic, cooperatively breeding riflemenen
dc.typeJournal Articleen
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