Testing allopatric and ecological speciation in a morphologically and genetically diverse species flock of viviparous freshwater gastropods (Mollusca: Cerithioidea: Pachychilidae) in the ancient lakes of Sulawesi, Indonesia

辐射背景下的物种形成被认为是创造生物多样性的关键过程。湖泊中的适应性辐射为研究物种形成的生态学提供了几乎完美的条件，淡水腹足类是理想的模式生物。印度尼西亚苏拉威西岛上的古老马利利湖是当地特有物种的港湾，大约有16种胎生淡水蜗牛。这些钉螺不仅表现出高度的种间和种内形态分化，而且还表现出分子分化。基于线粒体DNA的分子系统学揭示了几个独立殖民于湖泊的古老谱系，并在每个支系内爆发了非常新的辐射，但在种群和物种水平上的关系尚未解决。与广泛分布的河流类群相反，湖泊物种的分子和形态进化速度高度不同，这表明与湖泊环境过渡和湖泊内栖息地利用相关的某些特征面临着很大的选择压力。因此，这项拟议的研究旨在通过(1)揭示主要支系关键种群内部和之间的基因流模式和谱系关系，以及(2)获得这些种群的生态分化的基线数据，以(3)量化表型-环境相关性和(4)评估特征效用，来检验与湖泊腹足类多样性在空间上演化相关的物种形成因素和过程的各种替代假说。应与其他研究人员合作，对腹足类新出现的物种形成模式与从特有鱼类和螃蟹中获得的物种模式进行一致性测试。

Speciation in the context of a radiation is regarded as a key process in the creation of organismic diversity. Adaptive radiations in lakes provide almost perfect conditions to study the ecology of speciation, with freshwater gastropods being ideal model organisms. The ancient Malili lakes on Sulawesi, Indonesia, harbour an endemic species flock of about 16 species of viviparous freshwater snails. These snails show not only a high degree of inter- and intraspecific morphological differentiation, but also of molecular divergence. A mtDNA based molecular phylogeny reveals several old lineages which independently colonized the lakes, and within each clade bursts of very recent radiation with unresolved relationships on the population and species level. The rates of molecular and morphological evolution have been found to be highly divergent in lake species as opposed to widespread riverine taxa, pointing to strong selective pressures on certain traits associated with transition to a lacustrine environment and habitat use within the lakes. The proposed study therefore aims to test various alternative hypotheses of speciation factors and processes relevant for the evolution of the lake gastropod diversity in space by (1) uncovering patterns of gene flow and genealogical relationships within and among key populations of major clades and (2) getting base-line data on ecological differentiation for these populations in order to (3) quantify phenotype-environment correlations and (4) evaluate trait utility. The emerging speciation pattern for the gastropods shall be tested for congruence with those gained - in a cooperative approach with other researchers - from endemic fishes and crabs.