Causations of a riverine radiation: Assessment and evaluation of the morphological and genetical differentiation in a species flock of viviparous gastropods (Cerithioidea: Pachychilidae)

湖泊中的物种集群经常被作为模式系统来研究，试图阐明适应性辐射的潜在进化机制。相比之下，河流辐射是罕见的，几乎没有研究。然而，由于特定的特征，河流环境为研究物种形成的潜在因素以及生物多样性的起源提供了新的视角。拟议项目的重点是居住在Kaek河（Chao Praya流域，泰国中部）的Brotia属胎生淡水腹足动物的一个特有的，形态多样的物种群。初步结果表明，湄公河流域系统作为一个假定的原产地，单系的物种群，其快速多样化。同域发生的两个到三个物种在采样地点，他们的生态分离不同的基板的喜好，和相关的营养专业化（齿舌形态），使这个河流辐射一个新的和潜在的高度信息化的模型系统。该项目将实地材料和生态数据的精密取样与形态学和分子遗传学分析相结合。我们将采用AFLP基因分型作为强有力的工具，以产生良好的解决系统发育重建和评估水平的遗传变异和凝聚力（估计种群内和种群间的基因流），阐明的作用，内在和外在因素的过程中的异域和/或生态物种形成。这将是补充的环境表型相关性和生活史参数（育雏大小和性能作为健身估计），这是必要的测试假设的原因，这个物种群的演变的数据。

Species flocks in lakes have frequently been examined as model systems in an attempt to elucidate the underlying evolutionary mechanisms of adaptive radiations. In contrast, riverine radiations are rare and hardly studied. However, due to specific characteristics a riverine setting provides a new perspective for studying potential factors of speciation and, thus, the genesis of biological diversity. The proposed project focuses on an endemic, morphologically diverse species flock of viviparous freshwater gastropods of the genus Brotia inhabiting the Kaek River (Chao Praya drainage, Central Thailand). Preliminary results indicate the Mekong drainage system as a putative area of origin, the monophyly of the species flock, and its rapid diversification. Sympatric occurrence of two to three species at sampling localities, their ecological separation by varying substrate preferences, and a correlated trophic specialization (radula morphology) renders this fluviatile radiation a new and potentially highly informative model system. This project combines sophisticated sampling of material and ecological data in the field with morphological and molecular genetic analyses. We ill employing AFLP genotyping as powerful tool to produce well-resolved phylogenetic reconstructions and to assess levels of genetic variation and cohesion (estimation of gene flow within and between populations) to illuminate the role of intrinsic and extrinsic factors in the course of allopatric and/or ecological speciation. This will be supplemented by data on environment-phenotype correlation and life-history parameters (brood size and performance as estimator for fitness) that is necessary to test assumptions on the causations of the evolution of this species flock.