Abstract

Ant colonies must assess the internal states of their members and coordinate their responses to changes in state. One important example of this is the sensing of colony hunger and the regulation of foraging behavior. In many ant species, workers’ own nutritional states at least partially determine how much they forage, and poorly nourished workers usually forage more, while well-nourished workers remain inside the nest. Workers in some species, such as the clonal raider ant Ooceraea biroi, mostly forage in response to larval signals. Here, we ask whether O. biroi larvae directly affect worker nutrition, and whether nutritional states in turn regulate workers’ foraging and feeding behavior. We find that larval signals do not detectably influence workers’ nutritional states or feeding behavior. Unlike in most other ant species, however, when colonies forage in response to larval signals, better-nourished O. biroi workers forage more. This suggests evolutionary modifications to the nature and strength of the relationship between nutritional state and foraging behavior in some ants. Nonetheless, worker nutritional states regulate feeding behavior as expected, with workers eating in proportion to their level of food deprivation. We discuss the implications of these results for the life history of O. biroi and the evolution of foraging regulation in social insects more generally. We suggest that the decoupling of regulatory mechanisms for feeding and foraging has parallels in the evolutionary elaboration of animal multicellularity.

Significance statement

Foraging in social insects is a cooperative behavior: workers forage for the colony, rather than just for themselves. In most species, workers primarily use their own hunger as proxies for the colony’s needs. However, some species use other sources of information. Clonal raider ants, for example, forage in response to signals from their larvae. Here, we ask whether they also forage when deprived of nutrition. Surprisingly, we find instead that they forage more when better fed, and that in unmanipulated colonies, larval signals override worker nutrition, suggesting that the regulation of foraging has been rewired in this species. We also find that workers feed in proportion to their nutrient deprivation, suggesting that the regulation of feeding has been conserved. We propose that the uncoupling of feeding and foraging machinery has parallels in the evolutionary elaboration of animal multicellularity.

中文翻译：

---

克隆袭击者中的觅食和喂养受到社会和个人饥饿的独立调节

摘要

蚁群必须评估其成员的内部状态，并协调其对状态变化的反应。一个重要的例子是对殖民地饥饿的感觉和对觅食行为的调节。在许多蚂蚁物种中，工人自己的营养状况至少部分决定了它们的觅食量，营养不良的工人通常会觅食更多，而营养丰富的工人则留在巢内。一些物种的工人，例如克隆入侵者蚂蚁Ooceraea biroi，主要是对幼虫信号做出反应而觅食。在这里，我们问是否O. biroi幼虫直接影响工人的营养，以及营养状况是否反过来调节工人的觅食和进食行为。我们发现，幼虫信号不会可检测地影响工人的营养状况或进食行为。但是，与大多数其他蚂蚁物种不同，当殖民地根据幼虫信号进行觅食时，营养更佳的比目鱼工人会觅食更多。这表明对某些蚂蚁的营养状态和觅食行为之间的关系的性质和强度进行了进化修饰。尽管如此，工人的营养状态仍按预期控制着喂养行为，工人的饮食与他们的食物匮乏程度成正比。我们讨论了这些结果对比罗伊藻的生活史的影响。以及社会昆虫中觅食调控的演变。我们建议，喂养和觅食的调节机制脱钩在动物多细胞性的进化过程中具有相似性。

重要性声明

在社交昆虫中觅食是一种合作行为：工人为殖民地觅食，而不仅仅是为自己觅食。在大多数物种中，工人主要使用自己的饥饿作为殖民地需求的代理。但是，某些物种使用其他信息来源。例如，克隆入侵者蚂蚁会根据幼虫的信号进行觅食。在这里，我们问他们剥夺营养时是否还会觅食。出人意料的是，我们发现他们进食更好时会觅食更多，而在未操纵的殖民地中，幼虫信号会覆盖工人的营养，这表明该物种已重新调整了觅食规则。我们还发现，工人的进食比例与他们的营养匮乏成比例，这表明进食规则得到了保留。