Is there an optimal number of helpers in Alpine marmot family groups?

Dominique Allainé and Fabienne Theuriau

Behavioral Ecology, 2004, vol. 15, issue 6, 916-924

Abstract: The consequence of helping behavior on breeders fitness is still controversial. We used multivariate analyses to investigate for the effects of male and female subordinates on breeders' components of fitness in the Alpine marmot, Marmota marmota. We found that male and female subordinates, respectively, increased and decreased juvenile survival during winter. Thus, we give evidence that male subordinates should be considered as helpers, and that helpers provided breeders with immediate reproductive success gains, whereas subordinates females were costly. Helpers had no positive effects on female body condition, on persistence (future survival) of dominants, and on future reproduction (occurrence and size of a litter). Helpers thus did not provide breeders with delayed fitness benefits, and therfore, the load-lightening hypothesis was not supported. On the contrary, helpers had delayed fitness cost for dominant males and, consequently, for dominant females. Immediate benefits counterbalanced by delayed costs suggested an optimal number of helpers in the family group both from male and female perspectives. An optimality model well predicted the observed mean number of helpers in Alpine marmot family groups. Optimal numbers of helpers were slightly different for males and females, suggesting a potential conflict of interest between dominants. We finally discuss the possible mechanisms of helping that may explain the observed pattern in the Alpine marmot. Copyright 2004.

Keywords: cooperative breeding; load-lightening hypothesis; Marmota marmota; mixed models; optimality (search for similar items in EconPapers)
Date: 2004
References: Add references at CitEc
Citations:

Downloads: (external link)
http://hdl.handle.net/10.1093/beheco/arh096 (application/pdf)
Access to full text is restricted to subscribers.

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:oup:beheco:v:15:y:2004:i:6:p:916-924

Ordering information: This journal article can be ordered from
https://academic.oup.com/journals

Access Statistics for this article

Behavioral Ecology is currently edited by Louise Barrett

More articles in Behavioral Ecology from International Society for Behavioral Ecology Oxford University Press, Great Clarendon Street, Oxford OX2 6DP, UK.
Bibliographic data for series maintained by Oxford University Press ().