CAREER:Using Multigene Phylogenies to Solve Early Euascomycete Relationships and Reconstruct the Origin and Losses of the Lichen Symbiosis

点击翻译按钮获取中文摘要

0133891LutzoniSymbiotic associations among distantly related organisms with complementary functions provided key innovations for two major biological radiations - the mitochondrial eukaryotes and plants (chloroplasts). Despite the indisputable significance of symbiosis as a major evolutionary force, very little is known about mutualism and its evolutionary consequences. One of the main reasons for this is the lack of studies that include both mutualists and non-mutualists, and that are designed specifically to address evolutionary issues associated with coevolutionary processes. The need of analytical tools for such comparative phylogenetic studies and a general lack of knowledge about the limitations of newly developed statistical methods compound this deficiency. This project by Dr. Francois Lutzoni at Duke University aims to address these issues by greatly extending previous taxon and gene sampling of earlier phylogenetic studies of lichenized and non-lichenized ascomycete fungi, developing new analytical tools and assessing their statistical properties through computer simulation studies, and training the next generation of biologists to take full advantage of new bioinformatic and genomic tools while grounded in a solid training in organismal biology and systematics. In recent work by the investigator and his colleagues, it was reported that the diversity of lichenized and non-lichenized fungi can be best explained by few evolutionary gains followed by many losses of the lichen symbiosis, and that major lineages of strictly non-lichenized species (including the form genera Penicillium and Aspergillus) unexpectedly turn out to be derived from lichen-forming ancestors. The ultimate goal of this study is to better understand the mechanisms leading up to the origin and losses of major symbiotic associations (ranging from mutualism to parasitism) using the lichen-forming and allied derived ascomycetes as a model system. This research will be integrated with teaching activities by establishing two new courses ("Symbiosis" and "Phylogenetics") and by reshaping one current course ("Systematic Biology") at Duke University.This project will advance our understanding of early Euascomycete relationships and will contribute toward reestablishing a supraordinal classification of this phylum - an effort that was neglected by mycologists for the last 20 years due to the difficulty in resolving broad relationships based on morphological characters alone. This phylogenetic framework is essential to reconstruct the evolution of the lichen-symbiosis and to assess its impact on the diversification and evolution of the Euascomycetes, including the switch to new substrates (including vascular plants, animals and humans), changes in biosynthetic pathways leading to the production of novel secondary compounds, and transitions to new types of interactions to obtain carbohydrates (including parasitism). The Ascomycetes contain the most species that affect the everyday lives of humans by infesting crops, degrading textiles, causing human and animal diseases; but the group also includes model organisms such as Aspergillus, Neurospora, Saccharomyces, and Schizosaccharomyces, and other species indispensable in the production of foods and medicines. Computer simulations, part of this project, will provide new insights in choosing and developing statistical tests for phylogenetic studies. Interdisciplinary training across traditional organismal evolutionary biology and systematics, with new fields of phylogenetics, bioinformatics, and genomics is essential to the development of the next generation of systematists and evolutionary biologists and will facilitate innovative research on symbiotic systems.