Cant M A, English S, Reeve H K, Field J
Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
Proc Biol Sci. 2006 Dec 7;273(1604):2977-84. doi: 10.1098/rspb.2006.3669.
Animals that live in cooperative societies form hierarchies in which dominant individuals reap disproportionate benefits from group cooperation. The stability of these societies requires subordinates to accept their inferior status rather than engage in escalated conflict with dominants over rank. Applying the logic of animal contests to these cases predicts that escalated conflict is more likely where subordinates are reproductively suppressed, where group productivity is high, relatedness is low, and where subordinates are relatively strong. We tested these four predictions in the field on co-foundress associations of the paper wasp Polistes dominulus by inducing contests over dominance rank experimentally. Subordinates with lower levels of ovarian development, and those in larger, more productive groups, were more likely to escalate in conflict with their dominant, as predicted. Neither genetic relatedness nor relative body size had significant effects on the probability of escalation. The original dominant emerged as the winner in all except one escalated contest. The results provide the first evidence that reproductive suppression of subordinates increases the threat of escalated conflict, and hence that reproductive sharing can promote stability of the dominant-subordinate relationship.
生活在合作社会中的动物会形成等级制度，在这种制度下，占主导地位的个体从群体合作中获得不成比例的利益。这些社会的稳定要求下属接受自己的低等地位，而不是与占主导地位的个体就等级展开升级冲突。将动物竞争的逻辑应用于这些情况可以预测，在下属的繁殖受到抑制、群体生产力高、亲缘关系低以及下属相对强壮的情况下，升级冲突更有可能发生。我们通过实验诱导对优势等级的竞争，在野外对造纸黄蜂多色胡蜂的共同创始者群体检验了这四个预测。正如预测的那样，卵巢发育水平较低的下属，以及那些处于更大、生产力更高群体中的下属，与占主导地位的个体发生升级冲突的可能性更大。亲缘关系和相对体型对升级概率均无显著影响。除了一场升级冲突外，原来的主导者在所有冲突中都成为了赢家。这些结果提供了首个证据，即对下属的繁殖抑制会增加升级冲突的威胁，因此繁殖共享可以促进主导-从属关系的稳定。
