EEL-Understanding the evolution of derived epiphytic liverworts (Lejeuneeae clade, Porellales)

亚世界性的Lejeuneaceae是苔类植物中最大的科，但其分类和多样性在不同的主要分支中认识不均匀。Lejeuneaceae在潮湿的热带地区尤其丰富，在那里它们构成了附生植物，特别是附生植物多样性的重要组成部分，大多数附生植物在Lejeuneeae部落中筑巢。早期对勒氏科植物多样化模式的重建表明，在整个新生代，多样性不断积累。然而，这些散度时间估计是基于稀疏采样的，并且可能因深度节点的过采样而产生偏差。该项目旨在通过增加采样，包括至少60%的已知物种多样性，生成基于Lejeuneeae的质体和核DNA序列的系统发育。将特别注意根据新产生的序列和公布的数据进行平衡的分类学和地理抽样，以便进一步改进目前的分类。获得的数据集将用于生成基于DNA序列变化的日期树，并结合来自Lejeuneaceae广泛化石记录的综合约束。为了探索发散时间估计的稳健性，将采用文献中的平均取代率来校准分子钟，并探索化石约束对重建的影响。该树将用于探索主要分支的生物地理学，重点研究形成现存分布的过程，包括新生代气候变化对Lejeuneeae分布和多样化的影响。将特别注意到附生植物和更普遍的附生植物的进化时间，这些附生植物最好生长在树皮上而不是维管植物的活叶子上。附生植物利用的是一个短暂的栖息地（被子植物主导的潮湿森林中幼稚园植物的活叶），在进化背景下，这是相当年轻的，而树皮上附生植物多样性的积累受到已经占据这些栖息地的分类群的竞争的限制。附生植物栖息地的进化年龄和短暂性可能表明，与常生附生植物（=一般附生植物）相比，常生附生植物在活叶上生长的多样性更高。

The subcosmopolitan Lejeuneaceae are the largest family of liverworts, but their taxonomy and diversity is unevenly understood among the different main clades. Lejeuneaceae are especially abundant in the humid tropics, where they make up an important component of the epiphytic, especially epiphyllous, diversity, with most epiphylls nesting in the tribe Lejeuneeae. Earlier reconstructions of diversification patterns in Lejeuneaceae pointed to a constant accumulation of diversity throughout the Cenozoic. However, these divergence time estimates were based on sparse sampling and were likely biased by oversampling of deep nodes.This project aims at generating a plastid and nuclear DNA sequence based phylogeny of Lejeuneeae with an increased sampling including at least 60% of the known species diversity. Particular attention will be given to a balanced taxonomic and geographic sampling, based on newly generated sequences and published data, allowing for further improvements of the current classification. The obtained dataset will be used to generate a dated tree based on DNA sequence variation with integrated constraints derived from the extensive fossil record of Lejeuneaceae. To explore the robustness of the divergence time estimates, average substitution rates from the literature will be employed to calibrate the molecular clock and to explore the impact of fossil constraints on the reconstructions. The dated tree will be used to explore the biogeography of major clades with focus on the processes shaping the extant distribution including the impact of Cenozoic climate changes on the distribution and diversification of Lejeuneeae. Special attention will be given to the timing of the evolution of epiphylls and more generalistic epiphytes, growing preferably on bark rather than on living leaves of vascular plants. Epiphylls exploit an ephemeral habitat (living leaves of euphyllophytes in angiosperm dominated moist forests) that is rather young in an evolutionary context, whereas the accumulation of epiphytic diversity on bark is limited by the competition with taxa occupying these habitats already. The evolutionary age and the short-lived nature of epiphyllic habitats may suggest a higher diversification rate in Lejeuneaceae growing preferably on living leaves compared to their relatives growing preferably on bark (= generalistic epiphytes).