Phylogeny, biogeography and character evolution in the tribe Desmodieae (Fabaceae: Papilionoideae), with special emphasis on the New Caledonian endemic genera.

The nearly cosmopolitan tribe Desmodieae (Fabaceae) includes many important genera for medicine and forage. However, the phylogenetic relationships among the infratribal groups circumscribed using morphological traits are still poorly known. In this study, we used chloroplast (rbcL, psbA-trnH) and nuclear (ITS-1) DNA sequences to investigate the molecular phylogeny and historical biogeography of Desmodieae, and infer ancestral states for several vegetative and reproductive traits. Three groups, corresponding to the Desmodium, Lespedeza, and Phyllodium groups sensu Ohashi were retrieved in the phylogenetic analyses. Conflicts in the topologies inferred from the chloroplast and nuclear datasets were detected. For instance, the Lespedeza clade was sister to the groups Phyllodium+Desmodium based on chloroplast DNA, but nested within the Desmodium group based on ITS-1. Moreover, the New Caledonian endemic genera Arthroclianthus and Nephrodesmus were not monophyletic but together formed a clade, which also included Hanslia and Ohwia based on chloroplast DNA. The hypothetical common ancestor of Desmodieae was dated to the Middle Oligocene (ca. 28.3Ma) and was likely an Asian shrub or tree producing indehiscent loments. Several colonization events towards Oceania, America, and Africa occurred (all less than ca. 17.5Ma), most probably through long distance dispersal. The fruits of Desmodieae repeatedly evolved from indehiscence to dehiscence. We also showed that indehiscent loments allow for more variability in the number of seeds per fruit than indehiscent legumes. Modularity seems here to allow variability in the number of ovules produced in a single ovary.

DNA barcoding: a new tool for palm taxonomists?

BACKGROUND AND AIMS: In the last decade, a new tool - DNA barcoding - was proposed to identify species. The technique of DNA barcoding is still being developed. The Consortium for the Barcode of Life's Plant Working Group (CBOL-PWG) selected two core markers (matK and rbcL) that now must be tested in as many taxa as possible. Although the taxonomy of palms (Arecaceae/Palmae) has been greatly improved in the past decades, taxonomic problems remain. Species complexes, for example, could significantly benefit from DNA barcoding. Palms have never before been subjected to a DNA barcoding test. METHODS: For this study, 40 out of the 48 species of the southeast Asian tribe Caryoteae (subfamily Coryphoideae) were included. In total, four DNA markers - three plastid encoded (matK, rbcL and psbA-trnH) and one nuclear encoded (nrITS2) - were analysed to determine if adequate variation exists to discriminate among species. KEY RESULTS: The combination of three markers - matK, rbcL and nrITS2 - results in 92 % species discrimination. This rate is high for a barcoding experiment. The two core markers suggested by the CBOL-PWG, rbcL and matK, have a low species discrimination rate and need to be supplemented by another marker. In Caryoteae, nrITS2 should be chosen over psbA-trnH to supplement the two 'core' markers. CONCLUSIONS: For the first time a test of DNA barcoding was conducted in Arecaceae. Considering that palms have highly variable mutation rates compared with other angiosperms, the results presented here are encouraging for developing DNA barcoding as a useful tool to identify species within this ecologically important tropical plant family.

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

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.

New species from the Galoka and Kalabenono massifs: two unknown and severely threatened mountainous areas in NW Madagascar.

The Galoka mountain chain, comprising principally the Galoka and Kalabenono massifs, situated at the northern edge of the Sambirano Region in NW Madagascar is an area that was virtually unknown botanically. It was visited three times between 2005 and 2007 as part of a floristic inventory. Both massifs contain the last remaining primary forests in the Galoka chain, which extends parallel to the coastline from South of Ambilobe to North of Ambanja. Several new species have been discovered amongst the collections, eight of which are described here.

Neoendemism in Madagascan scaly tree ferns results from recent, coincident diversification bursts.

More than 80% of Madagascar's 12,000 plant species are endemic with the degree of endemism reaching as much as 95% in the scaly tree ferns, an important species rich component of Madagascar's evergreen rainforests. Predominantly African or Asian ancestry and divergence times usually postdating the separation of Madagascar from the Gondwanan landmasses have been demonstrated for several Madagascan animal and angiosperm groups. However, evolutionary studies of rainforest-specific lineages are scarce and the ecological context of radiation events has rarely been investigated. Here, we examine the evolution of Madagascan tree ferns as a rainforest-specific model family, integrate results from bioclimatic niche analysis with a dated phylogenetic framework, and propose an evolutionary scenario casting new light on our knowledge of the evolution of large island endemic clades. We show that Madagascar's extant tree fern diversity springs from three distinct ancestors independently colonizing Madagascar in the Miocene and that these three monophyletic clades diversified in three coincident radiation bursts during the Pliocene, reaching exceptionally high diversification rates and most likely responding to a common climatic trigger. Recent diversification bursts may thus have played a major role in the evolution of the extant Madagascan rainforest biome, which hence contains a significant number of young, neoendemic taxa.

Incorporating evolutionary history into conservation planning in biodiversity hotspots.

There is increased evidence that incorporating evolutionary history directly in conservation actions is beneficial, particularly given the likelihood that extinction is not random and that phylogenetic diversity (PD) is lost at higher rates than species diversity. This evidence is even more compelling in biodiversity hotspots, such as Madagascar, where less than 10% of the original vegetation remains. Here, we use the Leguminosae, an ecologically and economically important plant family, and a combination of phylogenetics and species distribution modelling, to assess biodiversity patterns and identify regions, coevolutionary processes and ecological factors that are important in shaping this diversity, especially during the Quaternary. We show evidence that species distribution and community PD are predicted by watershed boundaries, which enable the identification of a network of refugia and dispersal corridors that were perhaps important for maintaining community integrity during past climate change. Phylogenetically clustered communities are found in the southwest of the island at low elevation and share a suite of morphological characters (especially fruit morphology) indicative of coevolution with their main dispersers, the extinct and extant lemurs. Phylogenetically over-dispersed communities are found along the eastern coast at sea level and may have resulted from many independent dispersal events from the drier and more seasonal regions of Madagascar.

Molecular phylogeny of the fern genus Elaphoglossum (Elaphoglossaceae) based on chloroplast non-coding DNA sequences: contributions of species from the Indian Ocean area.

We performed a phylogenetic analysis of the fern genus Elaphoglossum using two non-coding chloroplast spacers: trnL-trnF and rps4-trnS. The sampling includes 123 species, of which 80 have not been previously sequenced, and for the first time includes species from Africa and the Indian Ocean area. The results of this expanded study largely agree with an earlier molecular study based on a smaller group of neotropical species and with the morphology-based classification of Mickel and Atehortua. We found, however, that some infrageneric groups such as section Elaphoglossum are not monophyletic. Besides section Elaphoglossum pro parte, we recognize six sections: two new monospecific, unnamed sections, and the previously established sections Lepidoglossa, Squamipedia, Amygdalifolia, and "Subulate-scaled clade." We divide the subulate-scaled clade into subsection Setosa (hydathodes present) and Polytrichia (hydathodes absent), and section Elaphoglossum is divided into subsections Platyglossa and Pachyglossa, two groups that do not appear to be supported by any single morphological character. In general, however, the main clades are supported by morphology. Finally, we discuss the species of the Indian Ocean region and their affinities with the neotropical ones. Out of the 11 species pairs postulated by Moran and Smith on the basis of morphology, two are well supported (E. eximium-E. aubertii; E. piloselloides-E. spatulatum) and three are not supported (E. ciliatum-E. humbertii; E. muscosum-E. poolii; E. paleaceum-E. deckenii), and two remain unresolved (E. erinaceum-E. hybridum; E. glabellum-E. acrostichoides) because our molecular markers were not variable enough. Four species pairs could not be tested because specimens were lacking. Unsupported species pairs are best interpreted as morphological convergences. Two additional species pairs are proposed: E. cuspidatum-E. succisaefolium; E. doanense-E. hornei. Placement of the species from the Indian Ocean suggests that at least 13 long-distance dispersal events occurred between the Neotropics and the Indian Ocean-Africa.