Chemosystematics and Phylogenetics of South American Xanthoparmeliae

地衣是由藻类和真菌组成的共生生物。它们占陆地生态系统的约8%，是许多地区矿物循环的重要贡献者。它们也是二氧化硫等污染危害的重要生物指标。亚利桑那州立大学的托马斯·纳什博士正在研究南美洲黄原地衣属的地衣种类，以便确定可靠的形态和生化特征，以此来识别单个物种，并进一步试图确定这些分类群的进化亲缘关系。在各种地衣中发现了数百种新的化合物（所谓的“地衣物质”），有时被用作物种标记。纳什博士将测试这些化学类型是特定物种的稳定特征，还是随着地衣生长的环境条件而变化。他对南美地衣的分类学研究将补充南非、澳大拉西亚和北美正在进行或已完成的地衣属研究项目，最终将涵盖近400种地衣。

Lichens are symbiotic organisms composed of both an alga and a fungus. They dominate approximately 8% of terrestrial ecosystems and are important contributors to mineral cycling in many areas. Also they are important biological indicators of pollution hazards such as sulfur dioxide. Dr. Thomas Nash of Arizona State University is studying the species of lichens of the genus Xanthoparmelia in South America, in order to determine reliable morphological and biochemical characters by which to recognize individual species and further to attempt to determine the evolutionary affinities of these taxa. Hundreds of novel chemical compounds (so called "lichen substances") have been identified in various lichens, and used at times as species markers. Dr. Nash will test whether these chemical types are stable features of particular species or whether the chemistry varies with environmental conditions under which the lichens grow. His taxonomic work on South American lichens will complement projects underway or completed on this genus for South Africa, Australasia, and North America, covering ultimately nearly 400 species.