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Systematics Section / ASPT

Schönenberger, Jürg [3], Anderberg, Arne A. [2], Sytsma, Kenneth J. [1].

Molecular phylogenetics and patterns of floral evolution in the Ericales.

The diverse and species-rich order Ericales has found considerable interest among systematists in recent years. Molecular phylogenetic studies have not only convincingly demonstrated the monophyly of the order comprising 23 families formerly placed in three different subclasses (Asteridae, Dilleniidae, and Rosidae) but have also resolved Ericales as sister to euasterids. Most ericalean families are well-circumscribed and have been or are currently subject to intrafamilial phylogenetic studies. In spite of all the attention that Ericales have received recently, there remains a major challenge, i.e., the still largely unresolved deeper nodes in the ericalean phylogeny. The present study mainly aims (1) to improve our current knowledge of the inter-familial relationships by expanding on gene and taxon sampling and (2) to evaluate the evolution of important floral characters in the light of the resulting phylogeny. We add a nuclear region (26s rDNA) to already published data sets, summing up to a total of 11 molecular markers. Our analyses, applying both maximum parsimony and Bayesian inference, for the first time resolve some of the deeper nodes in the phylogeny. Strongly supported groups, previously unrecognized or only weakly supported, include: (1) the ‘higher Ericales’ comprising all families except Balsaminaceae, Tetrameristaceae, Marcgraviaceae, Fouquieriaceae, Polemoniaceae, and Lecythidaceae; (2) a clade with Sapotaceae, Ebenaceae and the primuloid families; (3) a clade with Symplocaceae, Styracaceae, Diapensiaceae; and (4) a clade comprising the latter three families plus Theaceae, Roridulaceae, Actinidiaceae, Sarraceniaceae, Clethraceae, Cyrillaceae, and Ericaceae. At the level of floral evolution, we demonstrate that sympetaly is a highly homoplasious character in the order; that a diplostemonous floral ground plan likely arose from haplostemonous flowers in Ericales; and that the combination of ovules with a single integument and cellular endosperm formation is characteristic for two of the major clades in the order.

1 - University of Wisconsin-Madison, Botany, 430 Lincoln Drive, Madison, Wisconsin, 53706-1381, USA
2 - Swedish Museum of Natural History, Department of Phanerogamic Botany, P.O. Box 50007, Stockholm, SE-104 05, Sweden
3 - Stockholm University, Department of Botany, Lilla Frescativägen 5, Stockholm, SE-106, Sweden

26S rDNA
floral evolution

Presentation Type: Paper
Session: 37-2
Location: Cottonwood B (Snowbird Center)
Date: Tuesday, August 3rd, 2004
Time: 2:15 PM
Abstract ID:271

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