Hildebrand, Terri J. , Haufler, Christopher H. .
Species boundaries in Lycopodium (Lycopodiaceae): A Revealing Method.
Recent systematic studies of the ancient plant lineage Lycopodium (Lycopodiaceae) have provided new insights on sectional relationships in the genus while also posing significant questions about molecular evolution, long branch attraction, and interpretation of data. In contrast, resolution of species boundaries within each section has been more elusive. Early enzyme electrophoretic studies of Section Obscura showed variation for only two marker loci and yielded inconclusive results overall. Inter-simple Sequence Repeats (ISSR's), a DNA sequence-based method producing hypervariable markers in other species, were no more informative than protein studies and yielded less consistent results. Low within-section sequence divergence (< 1%) observed in four chloroplast and one mitochondrial region also failed to define species limits within Lycopodium. In contrast to these other methods, initial investigations of species circumscription in Section Obscura using sequence fragments that are polymorphic in length (AFLP) show considerable promise. Samples from more than 100 representatives of four currently described species from North America and Asia revealed fragments from selective PCR amplification. Results from the UPGMA analyses of fragments produced from a single primer combination revealed two well-defined clades for L. obscura and L. dendroideum samples. Although most representatives of L. juniperoideum clustered into a single clade, five samples were interspersed with L. hickeyi samples that formed two distinct clades, one of which was basal in the section. Combining polymorphic fragment length data from two primer pairs also identified a number of relationships that correlated with biogeography. These initial results demonstrate the potential for polymorphic sequence fragments as a successful molecular method for evaluating species boundaries within Lycopodium and hint at their potential for addressing questions about hybridization within the genus.
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1 - University of Kansas, Department of Ecology & Evolutionary Biology, Haworth Hall, 1200 Sunnyside Ave, Lawrence, Kansas, 66045-7534, USA
Presentation Type: Oral Paper
Date: Monday, August 15th, 2005
Time: 10:15 AM