Hildebrand, Terri J. , Haufler, Christopher H. .
Revising Lycopodium phylogeny: chloroplasts, mitochrondria, and morphology yield new perspectives and prospects.
Phylogenetic relationships among 30 species representing nine sections within Lycopodium were inferred from analyses of nucleotide sequence variation. Chloroplast rpl16 intron and mitochondria 19S regions were sampled for all species, and a subset of species included sequences from the nuclear leafy intron. Our results were compared to previous studies of trnL spacer and chloroplast ITS sequences. Parsimony analyses of plastid sequences in the current study support the earlier proposed Lycopodium-Annotina clade and Lycopodiastrum as basal. In both earlier and current topologies, Complanata is the most derived section. We also suggest a Diphasium-Pseudodiphasium-Magellanica clade but, in contrast to earlier work, Pseudodiphasium-Magellanica is sister to Diphasium, not Obscura. Morphologically, there is good support for this association. Unlike Obscura, Diphasium and Pseudodiphasium share branchlet orientation, sporophyll arrangement, obconic gametophytes, and a non-dendroid habit. Lycopodium jussiaei, another member of Diphasium, grouped instead with Complanata. This association is consistent with chromosomal data. The increased chromosome number of L. jussiaei (n=90 vs. n=34) may have resulted from ancestral chromosome doubling and subsequent hybridization with a member of Complanata. Although plastid data resolved most sectional relationships with high bootstrap support, associations within sections remained unclear. Leafy intron sequences were obtained to address this lack of resolution. Two copies of this region were isolated, and variants of leafy1 appeared initially to segregate among sections. With further taxon sampling, segregation of leafy1 sequences altered; variants previously associated with one section were obtained from members of other sections. Instead of providing a more-refined resolution of relationships, leafy1 sequences emphasized the need for broad taxon sampling and potential problems associated with low copy nuclear regions. Integrating molecular data and morphology, a global revision of the genus is suggested.
1 - University of Kansas, Dept. Ecol. & Evol. Biol. and Natural History Museum, 1200 Sunnyside Ave., Lawrence, Kansas, 66045-7534, USA
Presentation Type: Paper
Location: Superior B (Cliff Lodge)
Date: Monday, August 2nd, 2004
Time: 10:45 AM