Franks Nigel R, Dechaume-Moncharmont François-Xavier, Hanmore Emma, Reynolds Jocelyn K
School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK.
Philos Trans R Soc Lond B Biol Sci. 2009 Mar 27;364(1518):845-52. doi: 10.1098/rstb.2008.0224.
Compromises between speed and accuracy are seemingly inevitable in decision-making when accuracy depends on time-consuming information gathering. In collective decision-making, such compromises are especially likely because information is shared to determine corporate policy. This political process will also take time. Speed-accuracy trade-offs occur among house-hunting rock ants, Temnothorax albipennis. A key aspect of their decision-making is quorum sensing in a potential new nest. Finding a sufficient number of nest-mates, i.e. a quorum threshold (QT), in a potential nest site indicates that many ants find it suitable. Quorum sensing collates information. However, the QT is also used as a switch, from recruitment of nest-mates to their new home by slow tandem running, to recruitment by carrying, which is three times faster. Although tandem running is slow, it effectively enables one successful ant to lead and teach another the route between the nests. Tandem running creates positive feedback; more and more ants are shown the way, as tandem followers become, in turn, tandem leaders. The resulting corps of trained ants can then quickly carry their nest-mates; but carried ants do not learn the route. Therefore, the QT seems to set both the amount of information gathered and the speed of the emigration. Low QTs might cause more errors and a slower emigration--the worst possible outcome. This possible paradox of quick decisions leading to slow implementation might be resolved if the ants could deploy another positive-feedback recruitment process when they have used a low QT. Reverse tandem runs occur after carrying has begun and lead ants back from the new nest to the old one. Here we show experimentally that reverse tandem runs can bring lost scouts into an active role in emigrations and can help to maintain high-speed emigrations. Thus, in rock ants, although quick decision-making and rapid implementation of choices are initially in opposition, a third recruitment method can restore rapid implementation after a snap decision. This work reveals a principle of widespread importance: the dynamics of collective decision-making (i.e. the politics) and the dynamics of policy implementation are sometimes intertwined, and only by analysing the mechanisms of both can we understand certain forms of adaptive organization.
当决策的准确性取决于耗时的信息收集时，在速度和准确性之间做出妥协似乎是不可避免的。在集体决策中，这种妥协尤其可能出现，因为信息共享是为了确定公司政策。这个政治过程也需要时间。在寻找巢穴的石蚁（Temnothorax albipennis）中会出现速度与准确性的权衡。它们决策的一个关键方面是在潜在新巢穴中的群体感应。在潜在巢穴地点找到足够数量的巢伴，即群体阈值（QT），表明许多蚂蚁认为它合适。群体感应会整理信息。然而，QT 也被用作一个开关，从通过缓慢的串联奔跑将巢伴招募到新家中，切换到通过搬运进行招募，搬运速度要快三倍。虽然串联奔跑很慢，但它能有效地让一只成功的蚂蚁带领并向另一只传授巢穴之间的路线。串联奔跑会产生正反馈；越来越多的蚂蚁被指明路线，因为串联跟随者反过来会成为串联领导者。由此产生的经过训练的蚂蚁队伍然后可以迅速搬运它们的巢伴；但是被搬运的蚂蚁学不会路线。因此，QT 似乎既设定了收集到的信息量，也设定了迁移的速度。低 QT 可能会导致更多错误和更慢的迁移——这是最糟糕的结果。如果蚂蚁在使用低 QT 时能够部署另一个正反馈招募过程，那么快速决策导致缓慢实施这个可能的悖论或许可以得到解决。反向串联奔跑在搬运开始后发生，会带领蚂蚁从新巢穴回到旧巢穴。我们在此通过实验表明，反向串联奔跑可以让迷路的侦察蚁在迁移中发挥积极作用，并有助于维持高速迁移。因此，在石蚁中，虽然快速决策和对选择的快速实施最初是相互对立的，但第三种招募方法可以在快速决策后恢复快速实施。这项研究揭示了一个具有广泛重要性的原则：集体决策的动态过程（即政治）和政策实施的动态过程有时是相互交织的，只有通过分析两者的机制，我们才能理解某些形式的适应性组织。
