|Schnell Ii, Raymond|
Submitted to: Systematic Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/29/2005
Publication Date: 2/27/2006
Citation: Meerow, A.W., Francisco-Ortega, J., Kuhn, D.N., Schnell II, R.J. 2006. Phylogenetic relationships and biogeography within the Eurasian clade of Amaryllidaceae based on plastid ndhF and nrDNA its sequences: lineage sorting in a reticulate area. Systematic Botany. 31(1):42-60 Interpretive Summary: The relationships of the genera within the Eurasian group of the Amaryllis family have not been well understood, despite the fact that the group includes such important flowering bulbs as daffodils, snowdrops and snowbells. We use both chloroplast and nuclear gene sequences to analyze the evolutionary relationships of all of the genera in the group. The genera Lycoris and Ungernia (East and Central Asian) are the first branch in our family trees. Both of our DNA sequence data sets resolve two large subgroups within the greater Mediterranean region: Galantheae, consisting of Acis, Galanthus and Leucojum; and Narcisseae (Narcissus and Sternbergia), the latter to which the genus Pancratium appears more closely related. There are also some areas where the trees are incongruent. When three small genera, Hannonia, Lapiedra and Vagaria, centered in North Africa, are removed from the sequence matrices, all incongruence disappears. We hypothesize that lineage sorting took place early in the history of these genera. We also use reconstruct biogeographic scenarios on our trees and discuss them in the context of the complex biogeographic history of the Mediterranean basin.
Technical Abstract: The relationships of the genera within the Eurasian clade of Amaryllidaceae have not been resolved previously with clarity. We analyzed plastid ndhF and rDNA ITS sequences for 33 and 29 taxa, respectively, representing all genera by at least one species, with both maximum parsimony and Bayesian analysis, alone and in combination. Both sequence matrices resolve the Central and East Asian tribe Lycorideae as sister to the Mediterranean-centered genera of the clade. Both data sets resolve two large subclades within the greater Mediterranean region: Galantheae, consisting of Acis, Galanthus and Leucojum; and Narcisseae (Narcissus and Sternbergia)/Pancratium but also have areas of incongruence when three monotypic or small genera, Hannonia, Lapiedra and Vagaria, centered in North Africa, are removed from the alignments, the two sequence matrices produce fully congruent topologies with increased support at many of the nodes. We hypothesize that lineage sorting took place after the divergence of Galantheae and Narcisseae/Pancratium from a common genepool of which Hannonia, Lapiedra and Vagaria have retained a mosaic of the ancestral haplotypes. We also use dispersal-vicariance analysis to reconstruct biogeographic scenarios on trees found with the combined matrix, and use the degree of ambiguity in the optimizations to evaluate the relative phylogenetic accuracy of the trees. The results of the dispersal-vicariance analysis are discussed in the context of the complex biogeographic history of the Mediterranean basin.