American Journal of Botany 91 10 1627 1644 2004 A SURVEY OF TRICOLPATE EUDICOT PHYLOGENETIC RELATIONSHIPS1 WALTER S JUDD2 4 AND RICHARD G OLMSTEAD3 Department of Botany University of Florida Gainesville Florida 32611 USA and 3Department of Biology University of Washington Seattle Washington 98195 USA 2 The phylogenetic structure of the tricolpate clade or eudicots is presented through a survey of their major subclades each of which is briefly characterized The tricolpate clade was first recognized in 1989 and has received extensive phylogenetic study Its major subclades recognized at ordinal and familial ranks are now apparent Ordinal and many other suprafamilial clades are briefly diagnosed i e the putative phenotypic synapomorphies for each major clade of tricolpates are listed and the support for the monophyly of each clade is assessed mainly through citation of the pertinent molecular phylogenetic literature The classification of the Angiosperm Phylogeny Group APG II expresses the current state of our knowledge of phylogenetic relationships among tricolpates and many of the major tricolpate clades can be diagnosed morphologically Key words angiosperms eudicots tricolpates Angiosperms traditionally have been divided into two primary groups based on the presence of a single cotyledon monocotyledons monocots or two cotyledons dicotyledons dicots A series of additional diagnostic traits made this division useful and has accounted for the long recognition of these groups in flowering plant classifications However phylogenetic analyses based on nuclear plastid and mitochondrial DNA sequences and morphology do not support this dichotomy Donoghue and Doyle 1989 Olmstead et al 1992a Chase et al 1993 Doyle et al 1994 Doyle 1996 1998 Mathews and Donoghue 1999 Graham and Olmstead 2000 Savolainen et al 2000a Soltis et al 2000 Hilu et al 2003 Zanis et al 2003 In virtually all published cladistic analyses the dicots form a paraphyletic complex and their diagnostic features are mainly plesiomorphic within angiosperms see also Soltis and Soltis 2004 although the monocots do constitute a clade Chase 2004 Nonetheless a large number of species previously considered dicots do constitute a well supported clade the tricolpates Donoghue and Doyle 1989 or eudicots Doyle and Hotton 1991 A synapomorphy of the tricolpate clade is pollen with three apertures tricolpate tricolporate pollen and derivatives thereof The tricolpate clade is the largest group of angiosperms containing perhaps 165 000 species in just over 300 families ca 64 of angiosperm diversity and encompassing phenomenal variation in morphological anatomical and biochemical features The clade also is characterized by cyclic flowers and the presence of differentiated outer and inner perianth members i e a calyx and corolla may be an additional albeit homoplasious synapomorphy Zanis et al 2003 The staminal filaments are usually slender bearing well differentiated anthers and most members have S type plastids in their sieve elements This clade was first recognized in the morphology based phylogenetic analysis of Donoghue and Doyle 1989 Their monophyly was soon thereafter supported by numerous molecular analyses Olmstead et al Manuscript received 27 January 2004 revision accepted 4 June 2004 The authors thank Mark Chase Doug Soltis and Jeff Palmer along with two anonymous reviewers for their helpful comments on an earlier version of this paper We also thank Darin Penneys and Norris Williams who assisted in the preparation of the figure 4 E mail wjudd botany ufl edu 1 1992a Chase et al 1993 Doyle et al 1994 Soltis et al 1997 2000 2003 Ka llersjo et al 1998 Nandi et al 1998 Hoot et al 1999 Savolainen et al 2000a b Hilu et al 2003 Zanis et al 2003 Kim et al 2004 This clade was first called the tricolpates Donoghue and Doyle 1989 but the name eudicots Doyle and Hotton 1991 has gained wider usage We prefer tricolpates because this name is both descriptive and avoids a connection with the nonmonophyletic assemblage Dicotyledoneae Embryos having two or more cotyledons are not synapomorphic for this clade because they are also characteristic of Coniferales Cycadales Gnetales and the basal grade of flowering plants from which monocots which as their name implies share the synapomorphy of a single cotyledon and tricolpates are derived During the past 15 years our understanding of phylogenetic relationships within tricolpates has improved dramatically This has been accomplished largely on the basis of phylogenetic analysis of molecular data with many studies representing collaborations of several authors and combining several data sets Chase et al 1993 Chase and Cox 1998 Soltis et al 1998 Hilu et al 2003 Thus we now have an accurate outline though incomplete in many details of phylogenetic relationships within tricolpates Fig 1 The classifications of the Angiosperm Phylogeny Group APG 1998 APG II 2003 have been based on these ongoing molecular analyses leading to the recognition of a series of putatively monophyletic orders and families Various secondary criteria such as strength of support for monophyly ease of recognition on the basis of phenotypic features minimization of taxonomic redundancy etc also are used in ranking decisions APG 1998 Backlund and Bremer 1998 Judd et al 2002 APG II 2003 The result is a classification that is phylogenetically accurate to the extent we can presently determine and that system is used with some slight modifications as the basis for the discussion of tricolpate diversity in this paper Despite tremendous advances in understanding phylogenetic pattern there is a need for more studies addressing the relationships between morphological characters and phylogenetic hypotheses based on DNA sequences Endress et al 2000 Studies such as those of Nandi et al 1998 Doyle and Endress 2000 and Zanis et al 2003 represent an effort either through combined analysis or by the mapping of morpholog 1627 1628 AMERICAN JOURNAL Fig 1 Phylogenetic relationships of major groups of Tricolpates Eudicots modified from APG II 2003 The names lamiids for euasterids I and campanulids for euasterids II were suggested by Bremer et al 2002 The names fabids for eurosids I and malvids for eurosids II are proposed here ical features on DNA based topologies towards integrating morphological and molecular characters Without careful integration of morphological and molecular data precise determination of the level of universality of particular morphological
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