Combined phylogenetic analyses reveal interfamilial relationships and patterns of floral evolution in the eudicot order Fabales

Abstract

Relationships between the four families placed in the angiosperm order Fabales (Leguminosae, Polygalaceae, Quillajaceae, Surianaceae) were hitherto poorly resolved. We combine published molecular data for the chloroplast regions matK and rbcL with 66 morphological characters surveyed for 73 ingroup and two outgroup species, and use Parsimony and Bayesian approaches to explore matrices with different missing data. All combined analyses using Parsimony recovered the topology Polygalaceae (Leguminosae (Quillajaceae + Surianaceae)). Bayesian analyses with matched morphological and molecular sampling recover the same topology, but analyses based on other data recover a different Bayesian topology: ((Polygalaceae + Leguminosae) (Quillajaceae + Surianaceae)). We explore the evolution of floral characters in the context of the more consistent topology: Polygalaceae (Leguminosae (Quillajaceae + Surianaceae)). This reveals synapomorphies for (Leguminosae (Quillajaceae + Surianaceae)) as the presence of free filaments and marginal ⁄ ventral placentation, for (Quillajaceae + Surianaceae) as pentamery and apocarpy, and for Leguminosae the presence of an abaxial median sepal and unicarpellate gynoecium. An octamerous androecium is synapomorphic for Polygalaceae. The development of papilionate flowers, and the evolutionary context in which these phenotypes appeared in Leguminosae and Polygalaceae, shows that the morphologies are convergent rather than synapomorphic within Fabales.

Legume phylogeny and classification in the 21st century: Progress, prospects and lessons for other species–rich clades

“…1), with Cercideae, Detarieae and Duparquetia Baill. alternatively resolved as the sister group to the remaining legumes depending on taxon sampling, locus sequenced and method of phylogenetic analysis (Bruneau & al., 2008;Bello & al., 2009Bello & al., , 2012. However, most recent phylogenetic evaluations of the family consider Cercideae to take that position (e.g., Doyle & al., 2000;Kajita & al., 2001;Bruneau & al., 2001Bruneau & al., , 2008Herendeen & al., 2003a;Wojciechowski, 2003;Wojciechowski & al., 2004;Bello & al., 2009).…”

“…For example, bilateral floral symmetry probably evolved multiple times in the legumes, in different ways in different groups within the family. A resolved phylogeny that incorporates floral development characters can provide insight into the nature of these putative convergences Bello & al., 2012). Finally the addition of morphological data to a DNA sequence dataset can provide greater resolution and clade support in the resulting phylogeny (e.g., Herendeen & al., 2003b;Fougère-Danezan & al., 2010;Redden & al., 2010;Cardoso & al., 2012a), though this is not always the case (e.g., Haston & al., 2003;Russell, 2004).…”

“…The monophyly of the family has never been questioned despite the continuing lack of very strong bootstrap support (91% or less) even in the most recent analyses, a feature that is attributable to short phylogenetic branches among families within the order Fabales (Bello & al., 2009(Bello & al., , 2010(Bello & al., , 2012. The Leguminosae is usually divided into three subfamilies, but there are those who continue to recognize three separate families (e.g., Steyermark & al., 1998Steyermark & al., , 1999Steyermark & al., , 2001Cullen & al., 2011) despite this view being widely regarded as untenable (e.g., Lewis & Schrire, 2003;Lewis & al., 2005).…”

Terata of two legume species with radialized corolla: some correlations in floral symmetry

“…For example, Etaballia (dalbergioid clade) is characterized by a polysymmetric non-papilionate corolla and monadelphous androecium. All these cases suggest that radial flower symmetry evolved repeatedly in the evolution of Leguminosae, as recent molecular phylogenetic studies indicate (Bello et al 2012;Cardoso et al 2012a, b).…”

Polygala retiefiana (Polygalaceae), a new species described from South Africa

“…(Bello et al 2010). Interfamilial relationships and patterns of floral evolution were also found between these four families (Bello et al 2012). …”