Is there an optimal number of helpers in Alpine marmot family groups?
Is there an optimal number of helpers in Alpine marmot family groups?
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DOI：
10.1093/beheco/arh096
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发表时间：
2004-11-01
影响因子：
2.4
通讯作者：
Theuriau, F
中科院分区：
文献类型：
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作者：
Allainé, D;Theuriau, F
帮助行为对饲养员健康的影响仍然存在争议。采用多元分析方法，研究了雄性和雌性下级对高山旱獭繁殖者适合度成分的影响。我们发现，雄性和雌性分别增加和减少幼虫在冬季的存活率。因此，我们提供的证据表明，男性下属应该被视为帮手，帮手为繁殖者提供了立竿见影的繁殖成功，而从属女性则代价高昂。帮手对雌性的身体状况、优势种的持久力(未来存活)和未来的繁殖(产仔次数和大小)没有积极的影响。因此，帮助者没有为繁育者提供延迟的健康益处，因此，负载减轻假说不被支持。相反，帮手推迟了占主导地位的男性的健康成本，从而推迟了占主导地位的女性的健康成本。由延迟成本抵消的直接利益表明，无论从男性还是女性的角度来看，家庭群体中的最佳帮助者数量都是合适的。最优模型很好地预测了高山旱獭家庭群体中观察到的平均帮手数量。男性和女性的最佳帮手数量略有不同，这表明统治者之间存在潜在的利益冲突。最后，我们讨论了可能的帮助机制，这可能解释了在高山旱獭中观察到的模式。
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.