Bryological and Lichenological Section/ABLS
Ryall, K , Whitton, J , Schofield, W.B. , Ellis, S , Shaw, A.J. .
Molecular phylogenetic investigation of interspecific variation in the moss Isothecium (Brachytheciaceae).
Isothecium myosuroides is an abundant and taxonomically problematic moss that occurs in Europe and on the west and east coasts of North America. It has sometimes been split into two taxa, I. myosuroides on the east coast of North America and in Europe, and I. stoloniferum on the west coast of North America. Isothecium stoloniferum has four distinct morphological types known as the ordinary, julaceous, coarse, and pinnate morphs. The degree to which the morphotypes are genetically distinct versus ecologically determined has been debated as has the distinction between I. stoloniferum and I. myosuroides, resulting in conflicting taxonomic treatments. This study uses phylogenetic analyses of the trnL-trnF and trnG regions of the chloroplast genome to examine relationships among the two species and four morphotypes. A combination of molecular phylogenetic evidence and morphology favors recognition of I. myosuroides, I. stoloniferum and I. cardotii as distinct species. Accessions of I. myosuroides form a trans-Atlantic monophyletic group. The remaining samples form two distinct groups that each include samples of two morphotypes within I. stoloniferum. Populations of julaceous and ordinary morphotypes form a monophyletic group recognized as I. stoloniferum. Populations of coarse and pinnate morphotypes form an unresolved polytomy at the base of the clade that includes accessions of I. myosuroides. Because this grouping is morphologically well-defined and phylogenetically distinct from the other taxa, we propose tentative recognition of coarse and pinnate morphotypes as I. cardotii.
1 - University of British Columbia, Botany Department, 3529-6270 University Boulevard, Vancouver, British Columbia, V6T 1Z4, Canada
2 - Duke University, Department of Biology, 139 Biological Sciences Building, PO Box 90338, Durham, North Carolina, 27708-0338, USA
Presentation Type: Paper
Location: Ballroom 3 (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 4:00 PM