The Evolution of Ericales: Recent Insights using both Morphology and Molecules
Fritsch, Peter W. , Almeda, Frank , Manchester, Steven R. .
Phylogeny and classification of Symplocaceae: Stasis, ranks, and the fossil record.
WE compared results from phylogenetic analysis of 28 morphological characters with previously published DNA sequence data from five gene regions to revise the classification of Symplocos (Ericales: Symplocaceae; 324 species), according to the supposition that taxa should be both ranked and monophyletic. Observed conflict between the morphological and molecular estimates was interpreted as both a rooting problem associated with high patristic distances between the ingroup and outgroups, and dramatically convergent floral morphology among two of the clades. Optimization of the morphological characters onto the combined molecular tree revealed that the large section Lodhra is not supported by any known morphological synapomorphy. The assignment of 234 species of Symplocos as yet unsampled for molecular data to nine subdivisions in the revised classification is based solely on morphological attributes. This exemplifies the predictive value of morphological phylogenetic data, despite recent assertions to the contrary. Because the type species of Symplocos is highly nested within the named nodes of the phylogeny, the epithet Symplocos is used for all four supraspecific subdivisions recognized within the genus, as required by the autonym rule of the ICBN. The mere abandonment of this rule would eliminate any potential confusion concerning the reference of names to clades; that is, there is no need for an alternative code on the basis of this shortcoming. Symplocos has a rich endocarp fossil record in the Northern Hemisphere spanning much of the Tertiary. In preparation for a comprehensive analysis of the historical biogeography of Symplocos based on phylogenetic and these fossil data, we have studied the endocarp morphology of most of its extant species by surveying several herbaria with large Symplocos holdings. Tracing the evolution of endocarp locule number onto the molecular phylogeny indicates that placement of at least some fossil endocarps at crown nodes as minimum divergence time constraints is feasible.
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1 - California Academy of Sciences, Department of Botany, 875 Howard Street, San Francisco, California, 94103-3009, USA
2 - University of Florida, Department of Botany, Florida Museum of Natural History, P.O. Box 117800, Gainesville, Florida, 32611-7800, USA
Presentation Type: Symposium or Colloquium Presentation
Date: Monday, July 31st, 2006
Time: 10:45 AM