DISSERTATION RESEARCH: Evaluating likelihood-based fossil-calibraition methods and timing of repeated incercontinental dispersal in a fossil-rich clade of Boraginaceae

化石通常被用来作为校准系统发育假说和绝对时间的最可靠的方法。在测试想法之前，通常需要校准，例如史前事件的时间或特征的变化率。该项目研究了一个化石丰富的植物群，隐苔科（Boraginaceae），以测试最近提出的两种未经测试的将化石纳入系统发育分析的方法。在评估了这些方法之后，系统发育关系的时间校准假设将被用于检验新世界两性分离，这是一种分布模式，可以在隐花科和许多其他植物群中看到，可能是鸟类在北美和南美之间长距离传播的结果。这个项目将为科学带来三个主要贡献。首先，评估将化石数据纳入系统发育研究的新方法将有利于所有使用化石数据的未来研究。重要的是，这些方法可以推广到任何使用形态学数据的研究。第二，新世界的两性分离现象很普遍，但尚未得到充分研究。这项研究将检验目前关于这种生物地理格局的假设。最后，本项目将产生一个关于隐苔科植物之间关系的假设，为这一大型且具有重要生态意义的植物群的分类和保护提供信息。

Fossils are routinely used as the most defensible method for calibrating phylogenetic hypotheses to absolute time. Calibration is often required before ideas can be tested, such as timing of a prehistoric event or rate of change of a trait. This project examines a fossil rich plant group, the Cryptanthinae (Boraginaceae), to test two recently proposed but untested methods for incorporating fossils in phylogenetic analyses. After evaluating these methods, the resulting time-calibrated hypothesis of phylogenetic relationships will be used to examine the New World amphitropical disjunction, a distribution pattern seen in the Cryptanthinae and many other groups of plants that is likely the result of long-distance dispersal by birds between North and South America. This project will result in three main contributions to science. First, evaluation of novel methods for incorporating fossil data into phylogenetic studies will benefit all future studies using fossil data. Importantly, these methods can be generalized to any study using morphological data. Second, New World amphitropical disjunction is common yet understudied. This study will test current hypotheses regarding this biogeographic pattern. Finally, this project will generate a hypothesis of relationships in the Cryptanthinae that will inform taxonomy and conservation in this large and ecologically important plant group.