Evolution and Distribution of Trichomycete Gut Fungi in Arthropods

毛霉菌是专性生活在各种昆虫、甲壳类动物和千足虫的肠道中的寄生真菌。寄主和生境的多样性，所有科的全世界性分布，以及这些真菌的某些属的洲际分布，表明这些真菌与节肢动物的关系非常古老。堪萨斯大学的Robert Lichtwardt博士试图了解毛霉菌是如何以及何时进化的，并与它们的节肢动物宿主一起在地理上分布。来自澳大利亚和新西兰的数据表明，一些真菌类群可能至少在7000万至8000万年前在冈瓦纳大陆上有共同的祖先。证据支持冈瓦纳起源的南方毛菌将寻求在南美洲南部。其他肠道真菌在海洋，陆地和淡水节肢动物的研究可能会提供证据，某些物种已经辐射与他们的主机，以及在异地分布的扩散和vicariance的作用。毛霉菌属的系统发育分析将有助于了解它们的进化和地理分布，来自世界不同地理区域的培养菌株的同工酶表型将提供一些关于物种变异的信息。Harpellales，其物种只生长在水生昆虫的幼虫阶段，将研究它们的繁殖体是否能与成虫一起扩散。

Trichomycetes are commensalistic fungi that live obligately in the guts of various insects, crustaceans, and millipedes. The variety of host and habitats, the worldwide occurrence of all families, and the intercontinental distribution of some genera of these fungi indicate that the relationship with arthropods is very ancient. Dr. Robert Lichtwardt of the University of Kansas seeks to understand how and when trichomycetes evolved and became geographically distributed with their arthropod hosts. Data from Australia and New Zealand suggest that some fungal taxa may have had common ancestors on Gondwana at least 70-80 million years ago. Evidence to support the Gondwanan origin of austral trichomycetes will be sought in southern South America. Studies of other gut fungi in marine, terrestrial, and freshwater arthropods may provide evidence of how long certain species have been radiating with their hosts, and the roles of dispersal and vicariance in allopatric distributions. Phylogenetic analysis of trichomycete genera will assist in understanding their evolution and biogeography, and isozyme phenotypes of cultured isolates from different geographical regions of the world will provide some information on species variability. Harpellales, whose species grow only in larval stages of aquatic insects, will be studied to see whether or not their propagules can disperse phoretically with adults.