Article was accepted under the Executive Editorship of Dr. Anthony DiFiore.
Males collectively defend their one-male units against bachelor males in a multi-level primate society
Version of Record online: 28 DEC 2013
© 2013 Wiley Periodicals, Inc.
American Journal of Primatology
Volume 76, Issue 7, pages 609–617, July 2014
How to Cite
Xiang, Z.-F., Yang, B.-H., Yu, Y., Yao, H., Grueter, C. C., Garber, P. A. and Li, M. (2014), Males collectively defend their one-male units against bachelor males in a multi-level primate society. Am. J. Primatol., 76: 609–617. doi: 10.1002/ajp.22254
Zuo-Fu Xiang and Bang-He Yang contributed equally to this paper.
- Issue online: 23 JUN 2014
- Version of Record online: 28 DEC 2013
- Manuscript Accepted: 4 DEC 2013
- Manuscript Revised: 30 NOV 2013
- Manuscript Received: 3 AUG 2013
- National Key Technology R&D Program of China. Grant Number: 2013BAD03B03
- National Natural Science Foundation of China. Grant Numbers: 31130061, 31150110464, 31071937, 30970427
- Innovation Platform Open Projects of Education Bureau of Hunan Province. Grant Number: 11K078
- State Forestry Administration of China
- Rhinopithecus roxellana;
- bachelor threat;
- male co-operation;
- paternity exclusion
Group-level male–male co-operation, which has been documented in several primate and non-primate societies, may be mutualistically advantageous to the participants when confronted with threats such as takeovers and cuckoldry by external males. Co-operation among members of distinct social units—while universal among humans—is extremely rare in non-human primates. We present the first observations of collective action or co-operation among males of different one-male units (OMU) in a multi-level society of Rhinopithecus roxellana. A total of 59 instances of male co-operation were recorded. Male co-operation included coordinated chasing, joint vigilance, and patrolling behavior directed at lone adult males trying to enter an OMU. Male co-operation was significantly more frequent during the mating season when the risk of incursions and extra-group paternity was higher. Paternity of infants born in the subsequent birth season and kin relationships among resident males were identified using microsatellite genotype. All infants were sired by OMU males, which we interpret as possible evidence for their success at thwarting mating attempts by satellite males. OMU males were principally unrelated suggesting that male co-operation is best understood in terms of the mutual direct benefits individuals obtain through collective action. Our findings lend support to the bachelor threat hypothesis in which the cooperative behavior of several individuals is more effective than the lone action of a single individual in providing mate defense. Our research has implications for understanding male bonding, higher-level collective action, and the evolution of social co-operation in human societies. Am. J. Primatol. 76:609–617, 2014. © 2013 Wiley Periodicals, Inc.