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Anne L. Engh Rebekah R. Hoffmeier Robert M. Seyfarth Dorothy L. Cheney 《Behavioral ecology and sociobiology》2009,64(1):97-104
Males in sexually dimorphic species like baboons appear to have surprisingly little influence on the reproduction and dominance
ranks of their female kin, even though they could potentially increase their fitness by helping their relatives improve their
ranks. Male baboons are able to dominate females several years before they emigrate, but their presence has no effect on relatives’
dominance ranks, at least when female kin are present. As a result, females usually acquire ranks within their matriline,
above their older sisters. We describe the process of rank acquisition among orphaned and non-orphaned juvenile and adolescent
females in a group of free-ranging baboons. Orphaned females were significantly more likely than non-orphaned females to acquire
unexpected ranks. Orphaned females with older sisters often acquired ranks within the matriline, but below their older sisters’.
Orphaned females with older brothers were likely to rise in rank above their matriline. Females’ interventions on behalf of
younger sisters always supported the existing female dominance hierarchy, while males’ interventions tended to act against
it. Similarly, in playback experiments, females appeared to be willing to support their younger sister only in disputes with
lower-ranking females. In contrast, males appeared to be willing to support their sister even in disputes with higher-ranking
females. Fraternal support enables females to improve their dominance ranks, but only if their mothers have died. It remains
a puzzle why males have so little influence on their female relatives’ ranks when female kin are present, and so much when
they are absent. 相似文献
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