Systematics Section / ASPT
Vidal-Russell, Romina , Nickrent, Daniel .
Misodendraceae: the first aerial parasites of Santalales.
MOLECULAR phylogenetic investigations have provided information on the relationships among the families of Santalales. The order contains five monophyletic families (Loranthaceae, Misodendraceae, Schoepfiaceae, Opiliaceae and Viscaceae) and two polyphyletic families (“Olacaceae” and “Santalaceae”). Olacaceae s. lat. is polyphyletic partly because Schoepfia is more closely related to Misodendrum and Loranthaceae than to Olacaceae s. str. Although Olacaceae s. str. is sister to the remaining members of the order, relationships among the remaining families are not well resolved. Past molecular studies suggest five independent origins of aerial parasitism, however, which group first evolved this habit was not clear. To resolve relationships among the non-Olacaceous families, we generated sequences from five genes: nuclear SSU and LSU rDNA, and chloroplast rbcL, matK, and trnL-F. Sequences from 25 taxa representing all families in the order were used (including four Olacaceae as the outgroups). Separate and combined data partitions were analyzed with maximum parsimony and Bayesian inference. All partitions were generally congruent, thus the total evidence tree will be described. Two major clades were resolved: 1) Opiliaceae, Santalaceae and Viscaceae which was sister to 2) Loranthaceae, Misodendraceae and Schoepfiaceae. The latter family, sister to Misodendraceae, contained Quinchamalium and Arjona, previously considered members of Santalaceae. The common ancestor of Misodendrum and Schoepfiaceae was a root parasite, thus aerial parasitism arose subsequent to the divergence of Misodendrum which only parasitizes Nothofagus. From a time calibrated Santalales tree, we estimate that this divergence occurred ca. 75 mybp which preceeds the evolution of aerial parasitism in Loranthaceae (ca. 40 mybp) and is not incompatible with the fossil history of Nothofagus. Misodendrum has no tendency towards root parasitism and is highly adapted to the aerial parasitic habit. Its wind-dispersed seeds likely represent the earliest adaptation to stem parasitism, i.e. earlier than Loranthaceae with bird dispersed seeds.
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Misodendraceae page of Parasitic Plant Connection
1 - Southern Illinois University, Department of Plant Biology, 1125 Lincoln Drive, Carbondale, Illinois, 62901-6509, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 144/Performing Arts Center
Date: Tuesday, August 1st, 2006
Time: 2:45 PM