Chapter 5 Evolution of Trichomycetes

Trichomycetes as a fungal class live worldwide in the guts of a variety of arthropods (Nematocera, Plecoptera, Ephemeroptera, Trichoptera, Collembola, Isopoda) with ancient evolutionary histories. Th ese fungi have adapted themselves successfully to the guts of individual types of hosts, both morphologically and physiologically. It is hypothesized that the history of the fungal symbionts is also ancient, and that they may have begun their development as trichomycetes in the earlier stages of host evolution. As the arthropod hosts eventually became distributed to modern continents and islands, they carried with them their fungal partners. Some disjunct distributions apparently led to speciation of the host, and at times speciation of the fungi. Evidence suggests that the current wide distribution patterns of particular hosts and their fungi may sometimes be attributed to continental drift . It is very likely, based on collecting experiences in various parts of the world (Lichtwardt et al., 2001), that the vast majority of Trichomycetes are yet to be discovered. Some of these will undoubtedly be important missing taxa that will help molecular phylogenetic eff orts to better infer the evolutionary history of these interesting symbiotic fungi.