Phylogeny and Taxonomy of Ostropalean Fungi, with Emphasis on the Lichen-forming Thelotremataceae

直到一个半世纪以前，人们还认为，从苔原到炎热干燥的沙漠，在土壤、岩石和树木上生长的彩色地衣是与植物和真菌分离的生物。地衣与某些真菌和藻类的相似性部分是由地衣在分类上处于两者之间的中间位置这一观点所解释的。1867年，人们发现地衣实际上是真菌和藻类之间的一种共生关系，更具体地说，地衣形成真菌是一种特殊真菌的营养模式，地衣形成真菌逐渐被纳入真菌分类系统。第一次大规模分子、基于dna的地衣形成真菌系统发育（1995年）似乎证实了地衣化在真菌内部独立进化了许多次，但最近的一项研究（2001年）提出了另一种说法，即在子囊菌群中只有一次主要的地衣化事件，次生非地衣化真菌沿着几个谱系进化，包括曲霉和青霉等重要类群。对子囊菌分子系统发育的进一步研究表明，情况更为复杂，有一个或两个主要的地衣化事件，几个去地衣化事件，甚至可能有再地衣化事件。生物和形态上最多样化的真菌类群之一是东孢菌，包括地衣化和地衣化（寄生地衣的真菌）类群，以及非地衣化腐养菌和植物寄生虫。东蕨来源于一个地衣化的祖先，这意味着它们的非地衣化谱系被去衣化了，这些群体中的一些地衣形成真菌可能被二次再去衣化。为了验证这一假设，并与真菌生命之树项目密切合作，研究人员将重建东蕨的系统发育，强调从核和线粒体基因获得DNA序列数据，以及形态学和地衣化学研究，其中大部分是为了在亚洲和南美的实地考察中收集标本。在正在研究的类群中，丝虫科是迄今为止最大的科，大约有600种，其中300种是收集的目标。其成员构成了热带生态系统的重要组成部分。修订的属级分类将改进分类，促进生物地理学和生态学的研究。培训和外联是该项目的重要方面，其中将包括支助研究生论文工作、同外国同事及其学生联合实地考察、发展标本数据库供野外博物馆收藏，以及举办一个关于东蕨科和龙眼科的系统分类和鉴定钥匙的国际讲习班。

Until one and a half centuries ago, the colorful lichens that colonize soil, rocks and trees from the tundra to the hot and dry deserts were believed to be organisms separate from plants and fungi. Their similarity with certain fungi and algae was partly explained by the idea that lichens occupy a taxonomic position intermediate between those two groups. With the discovery (in 1867) that lichens are in fact a symbiosis between fungi and algae, and more particularly involve a mode of nutrition by specialized fungi, the lichen-forming fungi came gradually to be integrated into the fungal system of classification. The first large-scale molecular, DNA-based phylogeny of lichen-forming fungi (1995) seemed to confirm that lichenization evolved many times independently within the fungi, but a recent study (2001) has proposed an alternative, that there was only one major lichenization event within Ascomycota, from which secondarily non-lichenized fungi evolved along several lineages, including such important groups as Aspergillus and Penicillium. Additional studies on the molecular phylogeny of Ascomycota suggest that the situation is more complex, with one or two major lichenization events, several delichenization events, and possibly even relichenization events. One of the biologically and morphologically most diverse fungal groups are the Ostropales, which include lichenized and lichenicolous (fungi parasitizing lichens) groups, as well as non-lichenized saprotrophs and plant parasites. Ostropales are derived from a lichenized ancestor, which means that their non-lichenized lineages are delichenized and some lichen-forming fungi within these groups could be secondarily relichenized. To test this hypothesis, and in close collaboration with the Fungal Tree of Life project, the investigators will reconstruct the phylogeny of Ostropales, emphasizing acquisition of DNA sequence data from nuclear and mitochondrial genes along with morphological and lichen-chemistry studies, much of these for specimens to be collected on field trips in Asia and South America. Among the groups under study, the Thelotremataceae is by far the largest family, with about 600 species, and 300 are targeted for collection. Its members form an important component of tropical ecosystems. A revised genus-level classification for the group will improve classification and facilitate studies in biogeography and ecology. Training and outreach are important aspects of the project, which will include support for graduate student thesis work, joint field trips with foreign colleagues and their students, development of specimen databases for holdings at the Field Museum, and an international workshop on systematics and identification keys for Ostropales and Thelotremataceae.