Harvard University Herbaria

Phylogenetic Relationships

The monographic studies proposed here will provide a sound basis for establishing phylogenetic relationships within Pezizales, Sarcoscyphineae, and included genera. Present knowledge of phylogenetic relationships in these organisms is rudimentary. As noted above, Cabello (1988) conducted a numerical phenetic analysis of the genera, but with only limited reference to specimens. Throughout our studies, data will be assembled with an eye toward eventual phylogenetic analysis. This orientation will ensure, for example, the careful application of descriptive terms, so that structures referred to by a particular term are actually hypothesized to be homologous on the basis of preliminary similarity tests, including correspondence in position, development, and structural detail (Donoghue, 1992). The ultimate test of these preliminary homology assessments rests, of course, on phylogenetic analysis (Patterson, 1982), but our aim is to input into these analyses a set of characters that have been rigorously screened on the basis of the standard similarity criteria (Donoghue and Sanderson, 1994).

We will assemble data matrices for particular taxa as our monographic studies progress, and ultimately will construct a matrix for the entire clade. Phylogenetic analyses will test the delimitation of traditionally recognized taxa at all levels, and will provide an appropriate framework within which to study character evolution and historical biogeography (see below). Thus, we will assess the phylogenetic status of traditional subgroups within Pezizales and Sarcoscyphineae, as well as establish the direction and sequence of evolutionary events involving critical ascus wall, septal, and operculum characters. In view of the ability to connect life cycle stages through culture studies, we see special opportunities in this case to compare congruence and degree of resolution between phylogenies based on anamorph and teleomorph stages of the life cycle. It may emerge, for example, that a variety of distinct and distantly related teleomorphs have retained very similar anamorph stages, or vise versa, suggesting mosaic divergence of different stages of the life cycle.

Establishment of phylogenetic relationships will also allow us to explore a set of conceptual and practical issues surrounding phylogenetic classification (de Queiroz and Gauthier, 1992). We suspect that major taxonomic changes will be required, especially in view of the numerous monotypic genera now recognized, which may turn out to be nested within the larger groups (see Table 1).