Do mothers prefer helpers or smaller litters? Birth sex-ratio and litter size adjustment in cotton-top tamarins

Hdl Handle:
http://hdl.handle.net/10034/337991
Title:
Do mothers prefer helpers or smaller litters? Birth sex-ratio and litter size adjustment in cotton-top tamarins
Authors:
Boulton, Rebecca A.; Fletcher, Alison W. ( 0000-0003-2003-8033 )
Abstract:
Sex allocation theory has been a remarkably productive field in behavioural ecology with empirical evidence regularly supporting quantitative theoretical predictions. Across mammals in general and primates in particular however, support for the various hypotheses has been more equivocal. Population level sex ratio biases have often been interpreted as supportive, but evidence for small scale facultative adjustment has rarely been found. The helper repayment (HR) also named the local resource enhancement (LRE) hypothesis predicts that, in cooperatively breeding species, mothers invest more in the sex which assists with rearing future offspring, and that this bias will be more pronounced in mothers who require extra assistance (i.e. due to inexperience or a lack of available alloparents). We tested these hypotheses in captive cotton-top tamarins (Saguinus oedipus) utilising the international studbook and birth records obtained through a questionnaire from ISIS registered institutions. Infant sex, litter size, mother’s age, parity and group composition (presence of non-reproductive subordinate males and females) were determined from these records. The HR hypothesis was supported over the entire population, which was significantly biased towards males (the ‘helpful’ sex). We found little support for helper repayment at the individual level, as primiparous females and those in groups without alloparents did not exhibit more extreme tendencies to produce male infants. Primiparous females were, however, more likely to produce singleton litters. Singleton births were more likely to be male, which suggests that there may be an interaction between litter size adjustment and sex allocation. This may be interpreted as supportive of the HR hypothesis, but alternative explanations at both the proximate and ultimate levels are possible. These possibilities warrant further consideration when attempting to understand the ambiguous results of primate sex ratio studies so far.
Affiliation:
University of Chester
Citation:
Ecology & Evolution, 2015, 5(3), pp. 598-606
Publisher:
Wiley & Sons
Journal:
Ecology & Evolution
Publication Date:
8-Jan-2015
URI:
http://hdl.handle.net/10034/337991
DOI:
10.1002/ece3.1396
Additional Links:
http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2045-7758
Type:
Article
Language:
en
Description:
Boulton, R. A., & Fletcher, A. W. (2015). Do mothers prefer helpers or smaller litters? Birth sex-ratio and litter size adjustment in cotton-top tamarins. Ecology & Evolution, 5(3), 598-606 Copyright (c)2015, the authors, http://onlinelibrary.wiley.com/doi/10.1002/ece3.1396/full
ISSN:
2045-7758
Appears in Collections:
Biological Sciences

Full metadata record

DC FieldValue Language
dc.contributor.authorBoulton, Rebecca A.en
dc.contributor.authorFletcher, Alison W.en
dc.date.accessioned2015-01-09T14:46:01Zen
dc.date.available2015-01-09T14:46:01Zen
dc.date.issued2015-01-08en
dc.identifier.citationEcology & Evolution, 2015, 5(3), pp. 598-606en
dc.identifier.issn2045-7758en
dc.identifier.doi10.1002/ece3.1396en
dc.identifier.urihttp://hdl.handle.net/10034/337991en
dc.descriptionBoulton, R. A., & Fletcher, A. W. (2015). Do mothers prefer helpers or smaller litters? Birth sex-ratio and litter size adjustment in cotton-top tamarins. Ecology & Evolution, 5(3), 598-606 Copyright (c)2015, the authors, http://onlinelibrary.wiley.com/doi/10.1002/ece3.1396/fullen
dc.description.abstractSex allocation theory has been a remarkably productive field in behavioural ecology with empirical evidence regularly supporting quantitative theoretical predictions. Across mammals in general and primates in particular however, support for the various hypotheses has been more equivocal. Population level sex ratio biases have often been interpreted as supportive, but evidence for small scale facultative adjustment has rarely been found. The helper repayment (HR) also named the local resource enhancement (LRE) hypothesis predicts that, in cooperatively breeding species, mothers invest more in the sex which assists with rearing future offspring, and that this bias will be more pronounced in mothers who require extra assistance (i.e. due to inexperience or a lack of available alloparents). We tested these hypotheses in captive cotton-top tamarins (Saguinus oedipus) utilising the international studbook and birth records obtained through a questionnaire from ISIS registered institutions. Infant sex, litter size, mother’s age, parity and group composition (presence of non-reproductive subordinate males and females) were determined from these records. The HR hypothesis was supported over the entire population, which was significantly biased towards males (the ‘helpful’ sex). We found little support for helper repayment at the individual level, as primiparous females and those in groups without alloparents did not exhibit more extreme tendencies to produce male infants. Primiparous females were, however, more likely to produce singleton litters. Singleton births were more likely to be male, which suggests that there may be an interaction between litter size adjustment and sex allocation. This may be interpreted as supportive of the HR hypothesis, but alternative explanations at both the proximate and ultimate levels are possible. These possibilities warrant further consideration when attempting to understand the ambiguous results of primate sex ratio studies so far.en
dc.language.isoenen
dc.publisherWiley & Sonsen
dc.relation.urlhttp://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2045-7758en
dc.subjectsex allocationen
dc.subjectsaguinus oedipusen
dc.subjecthelper repayment hypothesisen
dc.subjectsex ratioen
dc.titleDo mothers prefer helpers or smaller litters? Birth sex-ratio and litter size adjustment in cotton-top tamarinsen
dc.typeArticleen
dc.contributor.departmentUniversity of Chesteren
dc.identifier.journalEcology & Evolutionen
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