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

点击翻译按钮获取中文摘要

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.