Spatial movement optimization in Amazonian Eciton burchellii army ants
Spatial movement optimization in Amazonian Eciton burchellii army ants
复制标题
亚马逊 Eciton burchellii 行军蚁的空间运动优化
作者：
S. K. Willson;R. Sharp;I. Ramler;A. Sen
觅食蚁群面临着许多动物共同面临的问题——如何最好地应对资源枯竭和环境异质性。行军蚁可能已经进化出了游牧的生活方式，以尽量减少对以前觅食区域的重新开发。然而，这种解决方案给蚁群带来了挑战：这个蚁群和其他蚁群的觅食造成了食物资源的变化，理论上，蚁群应该避免自己以前的觅食路径，也避免其他蚁群的觅食路径。在这里，我们研究了蚁群是如何利用这种资源镶嵌的，使用了弗兰克斯和弗莱彻（1983）首先提出和测试的一些最优性论点，但在亚马逊西南部的一个新地点使用了更大的数据集。我们的数据支持弗兰克斯和弗莱彻（1983）的模型，该模型在稳定阶段系统地避开被袭击的地区，以及连续稳定营地之间距离优化的假设。我们还测试并发现了重要的证据，即觅食袭击的方向与前一天的方向角度相反，而不是随机分布的角度，这将使一个群体远离最近开发的区域。这意味着，在游牧阶段，蚁群会走一条更直的路线，而不是走一条弯曲的路线，这可以最大限度地增加固定营地之间的距离。除了群体内运动优化之外，我们还研究了330多个群体迁移中群体间回避的证据，并表明群体特异性信息素并不一定排斥其他群体。最后，我们将我们的结果与在巴拿马巴罗科罗拉多岛（BCI）进行的类似研究进行了比较。尽管亚马逊西南地区的军蚁密度更高，但蚁群迁移的时间比BCI的同类要短，这表明亚马逊西南地区的猎物密度更高。
Foraging army ants face a problem general to many animals—how best to confront resource depletion and environmental heterogeneity. Army ants have presumably evolved a nomadic lifestyle as a way to minimize re-exploitation of previously foraged areas. However, this solution creates a challenge for an army ant colony: foraging by this colony and others creates a shifting landscape of food resources, where colonies should theoretically avoid their own previous foraging paths as well as those of other colonies. Here, we examine how colonies exploit this resource mosaic, using some of the optimality arguments first proposed and tested by Franks and Fletcher (1983), but with much larger data sets in a new location in SW Amazonia. Our data supported Franks and Fletcher’s (1983) model for systematic avoidance of raided areas during the statary phase, as well as a hypothesis of distance optimization between successive statary bivouacs. We also test and find significant evidence that foraging raids turn in opposite directions from the previous day’s directional angles more frequently than what would be expected if turning angles were distributed at random, which acts to move a colony away from recently exploited areas. This implies that colonies follow a straighter line path during the nomadic phase as opposed to a curved one, which acts to maximize distance between statary bivouacs. In addition to intra-colony movement optimization, we examine evidence for inter-colony avoidance from more than 330 colony emigrations and suggest that colony-specific pheromones are not necessarily repulsive to other colonies. Lastly, we compare our results with those of similar studies carried out at Barro Colorado Island (BCI), Panama. Despite a higher density of army ants in the SW Amazon region, colonies spend less time emigrating than their counterparts at BCI, which suggests a higher prey density in SW Amazonia.