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

亚广布的Lejeuneaceae是苔类植物中最大的一科，但其分类和多样性在不同的主要支系中了解不平衡。Lejeuneaceae在潮湿的热带地区特别丰富，它们是附生植物，特别是附生植物多样性的重要组成部分，大多数附生植物筑巢在Lejeuneae部落。早期对Lejeuneaceae多样性格局的重建表明，整个新生代都在不断积累多样性。然而，这些分歧时间估计是基于稀疏采样，并可能因对深层节点的过度采样而产生偏差。该项目旨在建立基于叶绿体和核DNA序列的Lejeuneeae系统发育图，增加采样包括至少60%的已知物种多样性。将特别注意根据新生成的序列和公布的数据进行平衡的分类和地理抽样，以便进一步改进目前的分类。所获得的数据集将被用来根据DNA序列变异和来自Lejeuneaceae的广泛化石记录的综合约束来生成日期树。为了探索发散时间估计的稳健性，将使用文献中的平均替换率来校准分子时钟，并探索化石限制对重建的影响。这棵古老的树将被用来探索主要分支的生物地理，重点是影响现存分布的过程，包括新生代气候变化对Lejeuneeae分布和多样性的影响。将特别注意附生植物和更一般的附生植物的进化时间，它们最好生长在树皮上，而不是维管植物的活叶上。附生植物利用了一种短暂的生境(被子植物占主导地位的潮湿森林中的真叶植物的活叶)，这种生境在进化背景下相当年轻，而树皮上附生植物多样性的积累受到竞争的限制，因为分类群已经占据了这些栖息地。附生生境的进化年龄和短暂的性质可能表明，与它们的近亲相比，生长在活叶上的Lejeuneaceae具有更高的多样性比率。

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).