Systematics of the Genus Cordyceps (Ascomycota, Hypocreales) and the Evolution of Host-shifts

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9806936 SPATAFORA The Clavicipitaceae (Ascomycota: Hypocreales) is a diverse, monophyletic family of fungi that is unusual in being composed entirely of obligate symbionts of other organisms: grasses, arthropods, or other fungi. A number of these species are of economic importance; they include, for example, the grass endophyte responsible for "staggers" in sheep. Cordyceps is the most diverse genus of the Clavicipitaceae, both in terms of number of species and in its morphology and remarkably wide range of hosts. The host range exhibited by Cordyceps and the Clavicipitaceae is inconsistent with a hypothesis of strict cospeciation ("host tracking"); if it were, then once a species became associated with a particular host, then all of its descendants would be associated with that host and its descendants. It is proposed that the current host range of Cordyceps and the Clavicipitaceae arose via a complex series of inter- and intrakingdom host-shifts. A robust reconstruction of the history (phylogeny) of these fungi is needed to test this hypothesis. None is currently available. In this research, Joseph Spatafora and Richard Humber will conduct a systematic investigation of the genus Cordyceps and allied clavicipitacean fungi. They will reconstruct the phylogeny of the fungi using characters from DNA sequence data and morphological studies. They will then use the phylogeny to develop a phylogenetically-based infrageneric classification of Cordyceps, integrate asexual fungi (anamorphs) into the classification of Cordyceps, and describe the history of host-shifts within the genus. The work should form a firm basis for ongoing and future work on the biology of this intellectually stimulating and economically important group of fungi.