PEET: A Unified Approach to Systematics of Basal Streptophytes (Charophycean Green Algae)

Project Summary

The proposal includes work intended to lead to a unified treatment of the basal streptophytes (green algal class Charophyceae). The basal streptophytes include five orders of green algae that are very closely related to land plants (embryophytes). The state of systematic work in each of these orders is different, in large part because of their very different morphologies, and because they were not historically classified together. Thus, the kind of work proposed for each order is different. The Coleochaetales are microscopic, branched filaments or discoidal thalli, have just over 20 named species, and have never been monographed. Field collections, morphological, and molecular systematic studies leading to a monograph of the Coleochaetales are proposed. The Charales are large, structurally complex algae often organized into stem-like nodes and internodes; there are roughly 240 species, and a monograph is available, but needs to be reconciled with modern phylogenetic data. Work to reconcile the monographic classification with molecular data is proposed; a major component of this work will be to prepare an interactive key to the sections. Few molecular data are available for the tribe Nitelleae, and this work is also proposed. The Zygnematales are abundant and environmentally important filamentous algae; they are a large group, with roughly 54 genera and 5000 species. Several monographs have been prepared, but the monophyly of some genera is uncertain, and molecular phylogenetic studies have identified some taxa (particularly Entransia and Mougeotia) that are of particular phylogenetic importance. Testing monophyly of each of the 54 genera, and more detailed study of Entransia and Mougeotia is proposed. The Klebsormidiales are unbranched filaments found in ponds or on soils. About 20 species are known, but because these algae have very few morphological characters, they are difficult to identify in nature. The Chlorokybales are a monotypic order of packet-forming coccoid algae that has very rarely been found in nature. Because both the Klebsormidiales and Chlorokybales have very few morphological characters, exploration of algal habitat with in situ molecular methods might reveal significant, previously unidentified diversity.

In addition to being of evolutionary and environmental importance, the basal streptophytes are a good laboratory for systematic training. With the exception of the co-PIs, most of the taxonomic experts in the group are retired, are no longer active in taxonomy, or are approaching retirement. In addition, the number of organisms is small enough that substantial progress toward a monograph can be accomplished during the 5 year duration of the project. During the course of the project, one visiting scholar, approximately five graduate students and ten undergraduates will receive training in systematics and will gain familiarity with the basal streptophytes. Several of these will probably go on to become world experts in the group. In addition to classroom training in alpha taxonomy and higher level systematics (using both morphological and molecular methods), the students will also gain curatorial and field experience. To ensure that the knowledge gained here becomes widely and readily available, an extensive database and image collection will be placed on the world-wide web, and made available as a CD-ROM, and to facilitate identification of the organisms by non-experts, a novel, phylogeny-based keying system ("visual keying") will be developed.