Dissertation Research: Systematics of Ulvaceae (Ulvales, Chlorophyta) using Nuclear and Chloroplast DNA Sequences

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0073169Waaland and Hayden Despite numerous DNA-based systematic and phylogenetic studies of land plants in the past decade, some major green plant lineages await exploration. The green algal division Chlorophyta contains many such groups, including the Ulvaceae (Ulvales, Ulvophyceae). Ulvaceae are morphologically simple cosmopolitan, macroscopic algae of marine and freshwater environments. Two members of the family, Ulva and Enteromorpha, are among the most familiar green seaweed genera. Common as ship fouling algae, they also are often implicated in "green tides" which result from excessive accumulations of their biomass following a bloom event. In addition to direct smothering of marine fauna, hydrogen sulfide released from the decaying biomass of green tides can present major health concerns for humans and marine communities. Morphological simplicity and phenotypic plasticity have thwarted pastattempts by systematists to diagnose natural groupings within the species-rich genera Ulva and Enteromorpha as well as among these and other genera inthe family. Graduate student Hillary Hayden, directed by Dr. J. Robert Waaland, will be studying the taxonomic affinities and systematic relationships of these genera, with an emphasis on new DNA-sequence data from both nuclear and chloroplast genes, for comparative analyses of mutational differences among the species. An improved understanding of Ulvaceae systematics is necessary for interpreting green tide phenomena and recognizing non-indigenous species. Further, biologists will benefit from a better understanding of phylogenetic relationships among these taxa and the complexity of phenotypic changes exhibited among a very closely related group of algae.