Exploring phylogenetic aspects of radiations of derived ferns: using the epiphytic polygrammoid as a model lineage

该项目的目标是提供多样化事件的系统发育结构的见解。几个独立的辐射将被研究，但这些都连接在一个系统发育框架。这种方法将产生关于替代率、物种形成率和关键创新等因素之间拟议相关性的新数据。选择Polygrammoid蕨类植物作为模型系统，其基础是（1）提供系统发育框架的组的良好建立的全球系统发育，（2）保守的生态偏好（附生），以及（3）初步结果表明，在8个选定的多样化事件中，替代率和/或物种形成率和/或关键创新之间的相关性。每种辐射的遗传学将重建的cpDNA区域和核基因的核苷酸序列，包括和不包括形态特征。分类单元取样将涵盖这些分支的大部分多样性。将计算每个多样化事件的替代率和物种形成率，并进行测试，以探索这两个速率之间的相关性和关键创新的影响，如腐殖收集器，蚂蚁蕨类植物的相互作用，提高耐干燥性，和绿色孢子。理论方面将探讨使用与所产生的经验数据进行比较的多样化事件的模型。

The objective of the project is to provide insights in the phylogenetic structure of diversification events. Several independent radiations will be studied but these are connected in a phylogenetic framework. This approach will generate new data about proposed correlations between factors such as substitution rates, speciation rate, and key innovation. Polygrammoid ferns are chosen as a model system based (1) on the well-established global phylogeny of the group providing a phylogenetic framework, (2) the conserved ecological preference (epiphytism), and (3) preliminary results that indicate correlations between substitution rate and/or speciation rate and/or key innovations in eight selected diversification events. The phylogeny of each radiation will be reconstructed using nucleotide sequences of cpDNA regions and nuclear genes with and without including morphological characters. Taxon sampling will cover substantial part of the diversity of these clades. Substitution rates and speciation rates will be calculated for each diversification event and tests will be performed to explore correlations between these two rates and the influence of key innovations such as humus collectors, ant-fern interaction, improved desiccation tolerance, and green spores. Theoretical aspects will be explored using models of diversification events that are compared with the generated empirical data.