Dissertation Research: Evolutionary History of Reproductive Systems in Closely Related Taxa of the Lichen-forming Genus Porpidia (Ascomycota)

0105024 Mueller本研究项目的总体目标是阐明Porpidia属（地衣形成子囊菌门）内的关系，并分析其物种内和物种间生殖模式之间的分布和相互依赖性。选择该属，是因为它积累了密切相关的类群，显示出截然不同的生殖模式。选择了黄蓝青霉（有性）/黑色素青霉（无性）“种对”进行详细的种群水平分析。两种繁殖模式之间的变化的假设模式将使用系统发育的方法进行测试。将使用综合地理学和系谱学分析来研究“物种对”内的基本种群结构和历史。今天，有性和无性生殖模式的意义及其持续共存仍然没有解决，尽管这个问题已经得到了深入的理论关注。这种情况部分是由于可用的经验数据的稀缺性和不同的性质，这不允许提出的假设进行严格的测试。模型系统，如Porpidia，包括密切相关的物种与不同的生殖模式，从有性到无性提供了重要的手段，以了解历史和后果的不同水平的重组。到目前为止，调查几乎完全集中在系统发育或种群遗传方面的问题。本研究将是第一个在地衣子囊菌整合系统发育和种群遗传学的方法。它不仅可以推断出进化历史的模式，还可以深入了解潜在的人口过程和塑造这些模式的历史事件。

0105024MuellerThe overall objectives of this research project are to clarify relationships within the genus Porpidia (lichen-forming Ascomycota), and to analyze the distribution and interdependence of transitions between reproductive modes within and among its species. The genus was chosen, due to its accumulation of closely related taxa that show contrasting reproductive modes. The P. flavocoerulescens (sexual)/P. melinodes (asexual) "species pair" was selected for detailed population-level analyses. Hypothetical patterns of changes between the two modes of reproduction will be tested using a phylogenetic approach. The underlying population structure and history within the "species pair" will be studied using an integrated phylogeographic and genealogical analysis.Today the significance of sexual and asexual reproductive modes and their continued coexistence are still unsolved, despite the in-depth theoretical attention the issue has received. This situation is in part due to the scarcity and disparate nature of available empirical data, which do not allow stringent tests of proposed hypotheses. Model systems such as Porpidia that include closely related species with different modes of reproduction ranging from sexual to asexual provide important means to gain insight into the history and consequences of different levels of recombination. So far, investigations have concentrated almost exclusively on either the phylogenetic or population-genetic aspects of the problem. The present study will be the first in lichenized ascomycetes to integrate both phylogenetic and population-genetic approaches. It will not only infer patterns of evolutionary history, but also provide insight into the underlying population processes and historical events shaping these patterns.