MOLECULAR PHYLOGENY OF THE TRIBE CHAREAE (CHARACEAE) BASED ON RBCL SEQUENCES

McCourt, R. 1 , Karol, K. G. 2 , Proctor, V. 3 , Feist, M. 41 Department of Botany, Academy of Natural Sciences, Philadelphia, PA, 19103USA; 2 Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742USA; 3 Department of Biology, Texas Tech University, Lubbock, TX, USA; 4 Université of Montpellier, Montpellier, France Sequences for the large subunit of the gene encoding RUBISCO (rbcL) were obtained for approximately 60 individuals in all six extant genera of the Characeae in two tribes: Tribe Chareae–Chara, Lamprothamnium, Lychnothamnus, Nitellopsis; Tribe Nitelleae–Nitella, Tolypella. Parsimony analysis (1,000 bootstrap replicates) tested monophyly of species isolates and genera of Chara, and tribes in the family. Species, genera, and tribes were strongly supported as monophyletic, except for paraphyly of a monoecious/dioecious species pair (C. globularis and C. connivens). Branch lengths within the Nitelleae were longer than in the Chareae, and bootstrap support for Nitella monophyly was less than for the other genera. The rbcL data support a monophyletic Chareae and Nitelleae. Within the genus, Chara sections sensu Wood are not monophyletic and in some cases are clearly paraphyletic (e.g., Grovesia). In contrast, subsections are generally well supported monophyletic groups (e.g., subsections Willdenowia and Wallmania). The data support the contention of Proctor that Wood's classification, derived from Braun's of the 19th century, is artificial and that the character defining the two sections (stipulode arrangement) is homoplasious. Mode of cortication (1‐, 2‐, or 3‐corticate), while exhibiting some homoplasy, appears to be a synapomorphic character state for some sub‐sections. Utility of characters across taxa in the family varies and is not an all‐or‐none categorization.