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

蚂蚁-植物共生是热带生态系统中常见的重要组成部分。在这些物种多样的生境中，生物相互作用可能是推动多样化的一个关键因素。在古热带地区最突出的蚂蚁-植物系统由先锋树属血桐及其与Crematogaster-ants的多种联系组成。在这个复杂的各种类型的相互作用及其相当程度的辐射有关的所有合作伙伴提供了一个特殊的模型系统，研究过程中的物种形成和辐射的互惠系统一般。我们的目标是分析可能导致我们系统中的分歧或破坏性选择的近似因素（生态，遗传或行为机制）。我们将测试是否竞争，在殖民地结构的变化或物种之间的特定相互作用的演变导致蚂蚁共生种群的遗传亚结构，因此可以提供在我们的系统中的物种形成的原材料。由于这两个群体的系统发育分析正在进行或已经完成，我们还可以询问与物种形成相关的性状进化问题，并确定启动植物相关蚂蚁辐射的关键创新。我们想测试这些特征是否是适应性的，即提供适应性优势并通过自然选择进化，或者只是显示系统发育的持久性。这些问题将结合实地观察和实验以及种群遗传分析来解决。

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.