Implications of a molecular phylogenetic study of the Malagasy genus Cedrelopsis and its relatives (Ptaeroxylaceae)

Department of Botany, Bergius Foundation, Stockholm University, Stockholm, Sweden.
Molecular Phylogenetics and Evolution (Impact Factor: 3.92). 10/2010; 57(1):258-65. DOI: 10.1016/j.ympev.2010.06.023
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Ptaeroxylaceae is an Afro-Malagasy family containing three genera, Bottegoa, Cedrelopsis, and Ptaeroxylon. Although the family is morphologically well delimited, it is currently considered part of the subfamily Spathelioideae in a broadly circumscribed orange family (Rutaceae). The Malagasy Cedrelopsis has traditionally been associated with different families of the order Sapindales and its phylogenetic placement in Rutaceae sensu lato has yet to be tested with molecular data. The present molecular phylogenetic study reaffirms the monophyly of Ptaeroxylaceae and its placement in Spathelioideae. Therefore, molecules and morphology support close affinities between Bottegoa, Cedrelopsis, and Ptaeroxylon and also their current generic circumscriptions. We report a case of an evolutionary change from one-seeded to two-seeded carpels within the Harrisonia-Cneorum-Ptaeroxylaceae clade of Spathelioideae. Finally, the sister-group relationship between the African Bottegoa and the Afro-Malagasy Ptaeroxylon-Cedrelopsis clade suggests an African origin of Cedrelopsis.

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Available from: Erik F Smets, Oct 06, 2015
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    • "Ptaeroxylon appeared as nested within Cedrelopsis in our previous analyses (Appelhans et al., 2011), but without support. Thus, the results of Razafimandimbison et al. (2010), although inferred from a lower taxon sampling, deliver the only statistically supported information about the relationship of the two genera. The resulting maximum clade credibility tree was used as input for Lagrange. "
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    ABSTRACT: Aim The family Rutaceae (rue family) is the largest within the eudicot order Sapindales and is distributed mainly in the tropical and subtropical regions of both the New World and the Old World, with a few genera in temperate zones. The main objective of this study is to present molecular dating and biogeographical analyses of the subfamily Spathelioideae, the earliest branching clade (which includes eight extant genera), to interpret the temporal and spatial origins of this group, ascertaining possible vicariant patterns and dispersal routes and inferring diversification rates through time. Location Pantropics. Methods A dataset comprising a complete taxon sampling at generic level (83.3% at species level) of Spathelioideae was used for a Bayesian molecular dating analysis (beast). Four fossil calibration points and an age constraint for Sapindales were applied. An ancestral area reconstruction analysis utilizing the dispersal–extinction–cladogenesis model and diversification rate analyses was conducted. Results Dating analyses indicate that Rutaceae and Spathelioideae are probably of Late Cretaceous origin, after which Spathelioideae split into a Neotropical and a Palaeotropical lineage. The Palaeotropical taxa have their origin inferred in Africa, with postulated dispersal events to the Mediterranean, the Canary Islands, Madagascar and Southeast Asia. The lineages within Spathelioideae evolved at a relatively constant diversification rate. However, abrupt changes in diversification rates are inferred from the beginning of the Miocene and during the Pliocene/Pleistocene. Main conclusions The geographical origin of Spathelioideae probably lies in Africa. The existence of a Neotropical lineage may be the result of a dispersal event at a time in the Late Cretaceous when South America and Africa were still quite close to each other (assuming that our age estimates are close to the actual ages), or by Gondwanan vicariance (assuming that our age estimates provide minimal ages only). Separation of land masses caused by sea level changes during the Pliocene and Pleistocene may have been triggers for speciation in the Caribbean genus Spathelia.
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    • "Spathelioideae (= Cneoroideae sensu Kubitzki et al. 2011) are a clade of about 30 species in eight genera that form the sister group to Rutaceae sensu stricto, and the clade is currently regarded as a subfamily of Rutaceae sensu lato (Chase et al. 1999; Groppo et al. 2008; Razafimandimbison et al. 2010; Appelhans et al. 2011). Prior to molecular phylogenetic analyses, these eight genera had not been regarded as close relatives due to their strikingly different morphology (see Appelhans et al. 2011), and they have been included in various Sapindalean /Rutalean families: Cneoraceae (Cneorum L.; Straka et al. 1976), Meliaceae (Cedrelopsis Baill., "
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    ABSTRACT: Subfamily Spathelioideae of Rutaceae constitutes a well-supported early branching clade of eight small woody genera that were formerly assigned to five different Sapindalean /Rutalean families. This study brings togeth-er detailed wood anatomical information on all eight genera (for four the wood anatomy is described for the first time in detail). Wood anatomy strongly supports the inclusion of all Spathelioid genera in Rutaceae and underpins the molecular phylogeny with a set of interesting apomorphies at different nodes of the cladogram. The wood anatomy of Cneorum tricoccon with its semi-ring porosity, dendritic vessel pattern, vascular tracheids and helical vessel wall thickenings stands out in Spathelioideae. This wood anatomical syndrome is hypothesized to be due to adaptive evolution for hydraulic safety and efficiency of this species in a typical Mediterranean climate, where similar syndromes have evolved in many unrelated clades of woody dicots. In at least six unrelated genera of Ruta-ceae outside Spathelioideae from Mediterranean or cool temperate and montane climates, the syndrome has also evolved in presumably paral-lel, adaptive evolution.
    IAWA journal / International Association of Wood Anatomists 01/2012; 33(4). DOI:10.1163/22941932-90000099 · 1.07 Impact Factor
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    • "However, no suitable material was available. The relationship between Ptaeroxylon and Cedrelopsis is not clear from our phylogenetic analyses, but they were sister groups in a study based on rps16 and trnL – trnF data (Razafimandimbison et al., 2010). The two groups of Cedrelopsis, Cedrelopsis A and Cedrelopsis B, are separated on the basis of their petal aestivation (valvate vs. imbricate), the length of the pedicel (sub-sessile flowers vs. long pedicel) and number of carpels (five vs. three to five) (Leroy et al., 1990). "
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    ABSTRACT: The Spathelia-Ptaeroxylon clade is a group of morphologically diverse plants that have been classified together as a result of molecular phylogenetic studies. The clade is currently included in Rutaceae and recognized at a subfamilial level (Spathelioideae) despite the fact that most of its genera have traditionally been associated with other families and that there are no obvious morphological synapomorphies for the clade. The aim of the present study is to construct phylogenetic trees for the Spathelia-Ptaeroxylon clade and to investigate anatomical characters in order to decide whether it should be kept in Rutaceae or recognized at the familial level. Anatomical characters were plotted on a cladogram to help explain character evolution within the group. Moreover, phylogenetic relationships and generic limits within the clade are also addressed. A species-level phylogenetic analysis of the Spathelia-Ptaeroxylon clade based on five plastid DNA regions (rbcL, atpB, trnL-trnF, rps16 and psbA-trnH) was conducted using Bayesian, maximum parsimony and maximum likelihood methods. Leaf and seed anatomical characters of all genera were (re)investigated by light and scanning electron microscopy. With the exception of Spathelia, all genera of the Spathelila-Ptaeroxylon clade are monophyletic. The typical leaf and seed anatomical characters of Rutaceae were found. Further, the presence of oil cells in the leaves provides a possible synapomorphy for the clade. The Spathelia-Ptaeroxylon clade is well placed in Rutaceae and it is reasonable to unite the genera into one subfamily (Spathelioideae). We propose a new tribal classification of Spathelioideae. A narrow circumscription of Spathelia is established to make the genus monophyletic, and Sohnreyia is resurrected to accommodate the South American species of Spathelia. The most recent common ancestor of Spathelioideae probably had leaves with secretory cavities and oil cells, haplostemonous flowers with appendaged staminal filaments, and a tracheidal tegmen.
    Annals of Botany 06/2011; 107(8):1259-77. DOI:10.1093/aob/mcr076 · 3.65 Impact Factor
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