Colony-level Response to Perturbation

戈登博士将研究收割机蚂蚁的社会组织，这种蚂蚁之所以被称为收割机蚂蚁，是因为它们收集和食用种子。这些蚂蚁在巢外做各种工作。觅食者沿着开阔的小路收集种子；巢穴维修工清理巢穴表面并维护巢穴内的隧道；巡逻员检查巢穴区域并对干扰或新的食物来源做出反应；居民工对蜂群垃圾堆或居民点进行分类和安排。每一项任务都是每天完成的，按照戈登博士所说的可预见的顺序完成。每日一轮的变化是为了响应蜂群环境的变化。戈登博士通过实验发现，执行不同任务的蚂蚁群体是相互依赖的。例如，如果她通过给蚁群额外的工作来增加巢穴的维护量，那么蜂群也会减少觅食。不同工人群体之间的这种互动取决于群体的年龄。在实验中受到干扰时，5岁的蜂群比2岁的蜂群更注重觅食。如果实验重复多次，年长的蜂群也会以同样的方式做出反应，而年轻的蜂群则会以许多不同的方式做出反应。由于单个蚂蚁的寿命只有一年左右，这不可能是因为5岁的蚂蚁群比2岁的蚂蚁群更老、更聪明。无论如何，殖民地的组织必须随着年龄的增长而改变。戈登博士将进行旨在帮助回答以下问题的实验：(1)当执行一项任务的人数增加导致执行另一项任务的人数减少时，这是因为蚂蚁正在切换任务，还是增加是因为从蚁穴内的储备蚂蚁中招募蚂蚁？戈登博士将对蚂蚁进行独特的标记，以识别个体。(2)年长的蜂群对实验的反应与年轻的蜂群不同是因为它们年长，还是因为它们含有更多的蚂蚁？戈登博士将把蚂蚁从较老的蚁群中移走，看看它们是否会表现出更年轻、更小的蚁群的行为。(3)改变一个群体行为的实验是否会导致相邻群体行为的改变？如果是这样，这可能有助于解释蜂群在争夺食物的环境中是如何相互作用的。戈登博士的研究将帮助我们理解一个复杂的社会如何在群体层面上发挥作用。觅食者的行为取决于影响觅食的条件：食物在哪里，食物的可获得性，蜂群有多少食物。但戈登博士的实验表明，觅食者的行为还取决于影响蚂蚁执行其他任务的事件，例如，要在蚁穴上做多少清理工作。不同工人群体之间的关系动态为蚂蚁社会如何在不断变化的环境中发挥作用提供了一个复杂的模型。这样的模式也可能适用于其他社会。

Dr. Gordon will investigate the social organization of harvester ants, so called because they collect and eat seeds. These ants do various tasks outside the nest. Foragers travel along cleared trails to collect seeds; nest-maintenance workers clear the surface of the nest mound and maintain tunnels inside the nest; patrollers inspect the nest area and respond to disturbances or new sources of food, and midden workers sort and arrange the colony refuse pile, or midden. Each task is done each day, in a predictable sequence that Dr. Gordon calls the "daily round" of the colony. The daily round changes in response to changes in the colony's environment. Dr. Gordon has found experimentally that groups of ants doing different tasks are interdependent. For example, if she increases the amount of nest maintenance by giving the colony extra work to do, the colony will also do less foraging. These interactions between different worker groups depend on the age of the colony. When disturbed experimentally, 5-year-old colonies emphasize foraging more than do 2- year-old colonies. The older colonies also respond in the same way if an experiment is repeated many times, while younger colonies respond in many different ways. As individual ants live only about a year, this cannot be because 5-year-old colonies contain older, "wiser" ants than do 2-year-old colonies. Somehow, the organization of the colony must change as it gets older. Dr. Gordon will carry out experiments designed to help answer the following questions: (1) When an increase in the numbers doing one task causes a decrease in the numbers doing another task, is this because ants are switching tasks, or do increases result from recruitment of ants from reserves inside the nest? Dr. Gordon will mark ants distinctively to identify individuals. (2) Do older colonies respond to experiments differently from younger colonies because they are older, or because they contain more ants? Dr. Gordon will remove ants from older colonies to see if they then act like younger, smaller colonies. (3) Do experiments that change the behavior of one colony cause changes in the behavior of neighboring colonies? If so, this may help to explain how colonies interact in an environment in which they are competing for food. Dr. Gordon's research will help us to understand how a complex society functions at the group level. A forager's behavior depends on the conditions affecting foraging: where food is, how accessible it is, how much food the colony has. But Dr. Gordon's experiments show that a forager's behavior also depends on events affecting the ants doing other tasks--for example, on how much clean-up work there is to be done on the nest mound. The dynamics of relationships between different worker groups suggest a complex model for how an ant society functions in an ever-changing environment. Such models may apply to other societies as well.