Carnivory in Lamiales: understanding character evolution, substitution rate plasticity, and genome miniaturization

在被子目拉米亚目中，肉食性植物的多样性最大，一些代表表现出最极端的肉食性综合症。这里发现了最小的被子植物核基因组，一些基因组区域显示出最高的DNA替换率。这些属性使该小组成为研究影响替代率和基因组大小变化的因素的完美模型系统。该项目希望为理解拉米亚目肉食性动物的进化成功以及伴随而来的形态适应、生理变化和非正统基因组进化提供基础。这就需要：(1)准确地确定莲科的亲缘关系，以及在密集的分类单元取样的基础上，获得更具代表性的Genlisea、Utrylaria和Pgucula主要亚系之间及其内部的关系图。这将使(2)历史生物地理分析和对多样化年龄、绝对多样化和替代率的准确估计成为可能，有助于将分子进化的转变与形态或生理上的关键创新联系起来。(3)将为密集抽样确定基因组大小和倍性水平，从而实现基于系统发育的相关性分析，这可能为推动极端基因组小型化的机制提供见解。(4)对四个完整的叶绿体基因组进行低成本的焦磷酸测序，并与来自非肉食性和寄生性近亲的已知基因组进行比较，将阐明肉食性动物对替换率、基因含量和正负选择DNA位点的影响，并有助于查明与寄生植物的相似之处。

In the angiosperm order Lamiales, the greatest diversity of carnivorous plants evolved, with some representatives exhibiting the most extreme embodiment of the carnivorous syndrome. The smal-lest angiosperm nuclear genomes have been found here, and some genomic regions exhibit one of the highest DNA substitutional rates reported. These attributes make the group a perfect model system for studying factors governing substitutional rate and genome size shifts. The project hopes to provide the basis for understanding the evolutionary success of carnivory in Lamiales, along with the accompanying morphological adaptations, physiological shifts, and unorthodox genome evolution. This requires (1) identifying precisely the affinities of Lentibulariaceae and the potentially closely related Byblis in Lamiales, as well as obtaining a more representative picture of relationships among and within major sublineages of Genlisea, Utricularia and Pinguicula, based on a dense taxon sampling. Results from this will allow (2) historical biogeographic analys-es and a precise estimation of diversification ages, absolute diversification- and substitution rates, serving to relate shifts in molecular evolution to morphological or physiological key innovations. (3) Genome sizes and ploidy levels will be determined for a dense sampling, enabling phylogeny-based correlation analyses that may provide insights in mechanisms driving the extreme genome miniaturization. (4) Cost-efficient pyrosequencing of four complete chloroplast genomes and comparisons with known genomes from non-carnivorous and parasitic relatives will illuminate the impact of carnivory on substitutional rates, gene content, and positively and negatively selected DNA sites, and allow to pinpoint similarities to parasitic plants.