Bayesian inference of phylogeny, morphology and range evolution reveals a complex evolutionary history in St. John's wort (Hypericum)

The genus Hypericum L. (> St. John's wort>, Hypericaceae) comprises nearly 500 species of shrubs, trees and herbs distributed mainly in temperate regions of the Northern Hemisphere, but also in high-altitude tropical and subtropical areas. Until now, molecular phylogenetic hypotheses on infra-generic relationships have been based solely on the nuclear marker ITS. Here, we used a full Bayesian approach to simultaneously reconstruct phylogenetic relationships, divergence times, and patterns of morphological and range evolution in Hypericum, using nuclear (ITS) and plastid DNA sequences (psbA-trnH, trnS-trnG, trnL-trnF) of 186 species representing 33 of the 36 described morphological sections. Consistent with other studies, we found that corrections of the branch length prior helped recover more realistic branch lengths in by-gene partitioned Bayesian analyses, but the effect was also seen within single genes if the overall mutation rate differed considerably among sites or regions. Our study confirms that Hypericum is not monophyletic with the genus Triadenum embedded within, and rejects the traditional infrageneric classification, with many sections being para- or polyphyletic. The small Western Palearctic sections Elodes and Adenotrias are the sister-group of a geographic dichotomy between a mainly New World clade and a large Old World clade. Bayesian reconstruction of morphological character states and range evolution show a complex pattern of morphological plasticity and inter-continental movement within the genus. The ancestors of Hypericum were probably tropical shrubs that migrated from Africa to the Palearctic in the Early Tertiary, concurrent with the expansion of tropical climates in northern latitudes. Global climate cooling from the Mid Tertiary onwards might have promoted adaptation to temperate conditions in some lineages, such as the development of the herbaceous habit or unspecialized corollas. © 2013 Elsevier Inc.This work was funded by the Spanish Ministry of Education and Science (project CGL2009-13322-C03-01/BOS) to I.S. and a PhD research grant AP-2007-01698 to A.S.M.Peer Reviewe

Revision of Geranium sections Azorelloida, Neoandina, and Paramensia (Geraniaceae)

The sections Azorelloida, Neoandina, and Paramensia of Geranium, all of them from the Andes, are taxonomically revised. Fruits with the ‘seed ejection-type’ dispersal have been found in all species, which allows classifying them within subg. Geranium. The sections Azorelloida and Paramensia consist of one and two species respectively, while section Neoandina comprises 24 taxa. Prior to this revision, the stemless species of Geranium from the Andes have been considered to belong to sect. Andina. Geranium sessiliflorum (type of Geranium sect. Andina), however, should be included in sect. Chilensia. Therefore, recently a new sect. Neoandina has been described to include most of the sect. Andina species (Aedo, 2000). Diagnostic morphological features are analysed and compared within and between the sections. The parsimony analysis suggested an early separation of sect. Paramensia from the rest of the ingroup constituted by the sections Azorelloida and Neoandina. These sections would later on have become separated into two groups: one with paramo species, and the other with more xerophilous, cold-resistant puna species. The biogeographic analyses using Fitch parsimony, dispersal-vicariance optimisation, and Bremer analysis support a paramo origin for the entire group in the North Andes, followed by a colonisation of southernmost regions (puna) and vicariance. A key, species descriptions, a complete list of synonymy, a list of specimens examined, and distribution maps are provided. Most species are illustrated for the first time. Fifteen lectotypes and one neotype are designated

Geographic barriers and Pleistocene climate change shaped patterns of genetic variation in the Eastern Afromontane biodiversity hotspot

The Eastern African Afromontane forest is getting increased attention in conservation studies because of its high endemicity levels and shrinking geographic distribution. Phylogeographic studies have found evidence of high levels of genetic variation structured across the Great Rift System. Here, we use the epiphytic plant species Canarina eminii to explore causal explanations for this pattern. Phylogeographic analyses were undertaken using plastid regions and AFLP fragments. Population genetic analyses, Statistical Parsimony, and Bayesian methods were used to infer genetic diversity, genealogical relationships, structure, gene flow barriers, and the spatiotemporal evolution of populations. A strong phylogeographic structure was found, with two reciprocally monophyletic lineages on each side of the Great Rift System, high genetic exclusivity, and restricted gene flow among mountain ranges. We explain this pattern by topographic and ecological changes driven by geological rifting in Eastern Africa. Subsequent genetic structure is attributed to Pleistocene climatic changes, in which sky-islands acted as long-Term refuges and cradles of genetic diversity. Our study highlights the importance of climate change and geographic barriers associated with the African Rift System in shaping population genetic patterns, as well as the need to preserve the high levels of exclusive and critically endangered biodiversity harboured by current patches of the Afromontane forest.Peer Reviewe

Reconstructing the history of Campanulaceae with a Bayesian approach to molecular dating and dispersal-vicariance analyses

We reconstruct here the spatial and temporal evolution of the Campanula alliance in order to better understand its evolutionary history. To increase phylogenetic resolution among major groups (Wahlenbergieae-Campanuleae), new sequences from the rbcL region were added to the trnL-F dataset obtained in a previous study. These phylogenies were used to infer ancestral areas and divergence times in Campanula and related genera using a Bayesian approach to molecular dating and dispersal-vicariance analyses that takes into account phylogenetic uncertainty. The new phylogenetic analysis confirms Platycodoneae as the sister group of Wahlenbergieae-Campanuleae, the two last ones inter-graded into a well-supported clade. Biogeographic and dating analyses suggest that Western Asia and the Eastern Mediterranean have played a major role as centers of migration and diversification within the Campanula alliance, probably in relation to the intense orogenic activity that took place in this region during the Late Neogene, and that could have promoted isolation and allopatric speciation within lineages. Diversification rates within several Campanula lineages would have increased at the end of the Miocene, coinciding with the Messinian Stage. Strong selective pressures from climate changes and the expansion of mountainous regions during this period are suggested to explain the adaptation to drought, cold or disturbed environments observed in many Campanula species. Several independent long-distance dispersal events to North America are inferred within the Rapunculus clade, which seem to be related to high ploidy levels. © 2009 Elsevier Inc. All rights reserved.This work has received financial support from the Ministerio de Educación y Ciencia (project reference: REN2003-04397). C.R. benefited from a grant (FI) from the Agència de Gestió d’Ajuts Universitaris i de Recerca, Generalitat de Catalunya. I.S. was funded by the ‘‘Ramon y Cajal” program of the Spanish Ministry of Education and Science. We thank the following herbaria for loans and studied and/or provided material: BC, BCB, ISTE, MA. UPSPeer Reviewe

A systematic survey of floral nectaries

The construction of classifications, as well as the understanding of biological diversity, depends upon a careful comparison of attributes of the organisms studied (Stuessy, 1990). It is widely known that data from diverse sources showing differences from taxon to taxon are of systematic significance. Dur-ing the 20th century, systematists have emphasized that their discipline involves a synthesis of all knowledge (Stevens, 1994) or, in other words, the variation of as many relevant characters as possible should be incorporated into the natural system to be constructed. The extent to which particular characters are constant or labile will determine their usefulness to syste-matics. In general, more conservative characters will be valuable in defining families and orders, whereas more labile characters may be useful at the ge-neric and specific levels (Webb, 1984). There is no doubt that floral characters are among the most used in the classification of flowering plants. At the same time, they constitute essential features in diagnostic keys to taxa in both taxonomic treatments and Floras (Cronquist, 1981, 1988).Fil: Bernardello, Gabriel Luis Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentin