Spatial-temporal evolution of Macaranga ant-plant lineages (Euphorbiaceae) in Southeast Asia

最近关于蚂蚁-植物互惠关系进化的研究激增，突显了人们对这一迷人现象的持续兴趣。最专门和最有效的保护蚂蚁-植物协会的形式是桃金娘。在这种共生中，植物为它们的伙伴蚂蚁提供筑巢空间和食物，而蚂蚁则保护它们的宿主植物免受草食动物、病原体和植被的侵蚀。在高等植物的进化过程中，菌生植物已经独立进化了150多次。为了了解促进苔藓植物性状起源和丧失的生态和进化环境，需要完整的样本和高分辨率的苔藓植物谱系及其近缘植物的系统发育。通过对传统标记基因座的Sanger测序分析，在许多没药植物谱系中观察到较差的系统发育分辨率，这可能是由于各自分支的最近起源(&lt；1500万年)。在这个项目中，我们将首次使用下一代测序技术(GBS)来解决东南亚蚂蚁植物Macaranga属真菌谱系之间和内部的系统发育关系。虽然许多Macaranga物种兼职地吸引蚂蚁，但来自马来西亚西部(包括婆罗洲、苏门答腊岛、马来半岛和周围岛屿；统称为Sundaland)的大约30种物种与9种火化蚂蚁专属共生。基于对234个标本的GBS分析，包括几乎所有的桃金娘属物种及其非桃金娘近缘物种，我们将重建该群体中桃金娘属的时空演化。在项目的第一部分，我们将进一步阐明何时、何地以及在什么情况下获得(和丢失)与肉质植物相关的形态特征，我们将检验肉质植物促进马卡朗加物种多样化和物种形成的假设。在该项目的第二部分，Sundaland生物地理学的一般方面将通过以GBS为基础的比较系统地理学方法来处理，其中包括来自五个具有不同生态要求和与蚂蚁关系的广泛分布物种的每个标本30至50个。我们的具体目标是了解过去孙达兰的气候和地理环境如何影响西部马来马卡朗加的种群结构和基因流动模式。

A recent proliferation of studies on the evolution of ant-plant mutualisms underlines the unbroken interest in this fascinating phenomenon. The most specialized and efficient form of protective ant-plant associations is myrmecophytism. In this symbiosis, the plants provide their partner ants with nesting space and food, while the ants protect their host plants against herbivores, pathogens and encroaching vegetation. Myrmecophytism has evolved more than 150 times independently during the evolution of higher plants. To understand the ecological and evolutionary circumstances that promote the origins and losses of myrmecophytic traits, well sampled and highly resolved phylogenies of the myrmecophytic plant lineages and their relatives are needed. Poor phylogenetic resolution has been observed in many myrmecophytic lineages that were analyzed by Sanger sequencing of traditional marker loci, probably owing to the recent origin (< 15 million years) of the respective clades. In this project we will use, for the first time, next generation sequencing technology (genotyping-by-sequencing, GBS) to resolve phylogenetic relationships among and within myrmecophytic lineages of the Southeast Asian ant-plant genus Macaranga. While many Macaranga species facultatively attract ants, about 30 species from western Malesia (comprising Borneo, Sumatra, the Malay Peninsula, and surrounding islands; collectively Sundaland) live in obligate symbiosis with nine species of Crematogaster ants. Based on a GBS-derived analysis of 234 specimens including almost all myrmecophytic Macaranga species and their non-myrmecophytic relatives, we will reconstruct the temporal-spatial evolution of myrmecophytism in the group. In the first part of the project, we will further elucidate when, where and under which circumstances morphological traits associated with myrmecophytism have been gained (and lost), and we will test the hypothesis that myrmecophytism enhanced diversification and speciation in Macaranga. In the second part of the project, general aspects of Sundaland biogeography will be addressed by a GBS-based, comparative phylogeographic approach including between 30 and 50 specimens each from five widely distributed species with different ecological requirements and relationships with ants. We specifically aim to understand how past climatic and geographic settings in Sundaland influenced the population structure and gene flow patterns of western Malesian Macaranga.