Mechanisms of speciation in Crematogaster spp. subgenus Decacrema associated with Macaranga

共生的反植物组织是热带生态系统中常见而重要的组成部分。在这些物种栖息地中，生物相互作用可能是推动物种多样化的关键因素。古热带地区最突出的抗植物系统包括先锋树属Macaranga及其与crematogaster蚂蚁的多种联系。这个复合体中各种类型的相互作用及其涉及所有伙伴的相当程度的辐射为研究一般互惠系统中的物种形成和辐射过程提供了一个特殊的模型系统。我们的目的是分析在我们的系统（生态、遗传或行为机制）中可能导致分化或破坏性选择的近似因素。我们将测试物种之间的竞争、群体结构的变化或特定相互作用的进化是否会导致蚂蚁共生体种群的遗传亚结构，从而为我们系统中的物种形成提供原材料。由于这两类蚂蚁的系统发育分析正在进行中或已经完成，我们也可以提出与物种形成相关的特征进化的问题，并确定在植物相关蚂蚁中开始辐射的关键创新。我们想要测试这些特征是否具有适应性，即提供了适应性优势并通过自然选择进化而来，还是仅仅表现出系统发育的持久性。这些问题将结合实地观察和实验以及种群遗传分析加以解决。

Mutualistic ant-plant associations are common and important elements of the tropical ecosystems. In these speciose habitats biotic interactions could be a crucial factor driving diversification. The most prominent ant-plant system in the palaeotropics consists of the pioneer tree genus Macaranga and its manifold associations with Crematogaster-ants. The various types of interaction in this complex and its considerable degree of radiation concerning all partners offer an exceptional model system for studying the processes of speciation and radiation in mutualistic systems in general. Our aim is to analyse the proximate factors that can lead to divergent or disruptive selection in our system (ecological, genetical or behavioural mechanisms). We will test whether competition, changes in colony structure or the evolution of specific interactions between species lead to a genetic substructuring of ant symbiont populations and can therefore provide the raw material for speciation in our system. Since phylogenetic analyses of both groups are on their way or already finished we can also ask questions about the evolution of traits correlated with speciation and determine the key innovations that started the radiation in the plant-associated ants. We want to test whether these traits are adaptive, i.e. provide a fitness advantage and evolved through natural selection, or show just phylogenetic persistence. These questions will be addressed with a combination of field observations and experiments, and population genetic analyses.