DISSERTATION RESEARCH: The evolution of plant-ants: mutualism and the gut microbiome

蚂蚁是许多陆地生态系统中数量最多的动物。 例如，它们占热带雨林树冠中昆虫的90%以上。这种数量上的优势意味着并非所有的蚂蚁都像人们曾经认为的那样是捕食者。 有些物种必须以营养贫乏的植物资源为食。金合欢蚂蚁就是一个很好的例子。它们生活在金合欢树上，专门以这些树提供的资源为食。为了换取在树上筑巢的空间和食物（主要是花蜜），蚂蚁积极地保护宿主树木免受吃树叶的昆虫，以及竞争植物和致病真菌的侵害。然而，由阿卡西亚斯提供的花蜜的营养成分对蚂蚁来说是不够的，这就提出了一个问题，即金合欢蚁群如何获得足够的营养来维持自己。一个可能的线索来自最近对包括人类在内的其他动物的研究，表明生活在肠道中的细菌有助于从食物中提取重要的营养素。这项研究将确定金合欢蚁是否也依赖于细菌伴侣来丰富饮食，以及这种伙伴关系是如何进化的。这项研究将帮助我们了解动物--也许有一天包括人类--是如何依靠营养不良的食物生存的。 由于蚂蚁是许多生态系统中具有影响力和主导地位的成员，因此了解它们如何获得营养对于全面了解环境中的能量流动至关重要。更一般地说，这项工作将告诉我们细菌在我们的生活和自然世界中越来越重要的作用;细菌在所有动物进化中的重要性才刚刚开始被认识。 该项目的研究人员将指导学生进行研究，并将通过向公众介绍和通过万维网上关于蚂蚁的博客分享他们的研究成果。

Ants are the most numerous animals in many terrestrial ecosystems. For example, they comprise more than 90% of insects in the canopy of tropical rain forests. This numerical dominance means that not all ants can be predators, as was once thought. Some species must instead feed on nutrient poor, plant-based resources. Acacia-ants are a good example. They live in acacia trees and feed exclusively on resources provided by these trees. In exchange for nesting space in the trees and food (mostly nectar), the ants aggressively protect host trees against insects that eat leaves, and against competing plants and disease-causing fungus. However, the nutritional content of the nectar provided by acacias is insufficient for the ants, raising the question of how colonies of acacia-ants obtain enough nourishment to sustain themselves. A possible clue comes from recent work with other animals, including humans, showing that bacteria living in the gut help to extract important nutrients from food. This research will determine whether acacia-ants also depend on bacterial partners for dietary enrichment, and how such partnerships have evolved.This study will help us understand how animals -- perhaps including humans, some day -- can live on nutritionally poor food. Because ants are influential and dominant members of many ecosystems, understanding how they obtain nutrition is essential for generating a comprehensive picture of energy flow through the environment. More generally, this work will teach us about the ever-increasing role of bacteria in our lives and in the natural world; the importance of bacteria in the evolution of all animals is just beginning to be appreciated. The researchers on this project will mentor students in research and will share their results through presentations to the public and through a blog about ants on the worldwide web.