A molecular systematic study of Ulva (Ulvaceae, Ulvales) from the northeast Pacific
2004
Hayden, Hillary S. | Waaland, J Robert
Species delineation in the genus Ulva is difficult due to a lack of distinguishing morphological characters and the high degree of phenotypic plasticity observed in these algae; thus, species descriptions are necessarily based on a limited set of characters. The present study uses molecular data to test species hypotheses for and explore species diversity in Ulva in the northeast Pacific. Samples of 21 taxa were collected from Valdez, Alaska to San Diego, California, additional Pacific locales outside this region, and Europe. Sequences from ITS nrDNA and the rbcL gene were analysed separately and simultaneously using maximum parsimony to reconstruct phylogeny. Molecular data resolve many of the species recognized by early and more recent treatments, reveal unanticipated potentially conspecific taxa and suggest that certain Ulva species are more widely distributed than may have been recognized previously. At least 12 species of Ulva were found in the northeast Pacific based on the present data: Ulva californica, U. intestinalis, U. lactuca, U. linza, U. lobata, U. pertusa, U. prolifera, U. pseudocurvata, U. rigida, U. stenophylla, U. taeniata and U. tanneri. Other Ulva species previously reported in this region were not encountered during the present study. In addition to providing insights into the systematics of Ulva, this paper indicates areas for additional research for this ubiquitous genus.
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