A jungle tale: Molecular phylogeny and divergence time estimates of the Desmopsis-Stenanona clade (Annonaceae) in Mesoamerica.

The predominantly Asian tribe Miliuseae (Annonaceae) includes over 37 Neotropical species that are mainly distributed across Mesoamerica, from southern Mexico to northern Colombia. The tremendous ecological and morphological diversity of this clade, including ramiflory, cauliflory, flagelliflory, and clonality, suggests adaptive radiation. Despite the spectacular phenotypic divergence of this clade, little is known about its phylogenetic and evolutionary history. In this study we used a nuclear DNA marker and seven chloroplast markers, and maximum parsimony, maximum likelihood and Bayesian inference methods to reconstruct a comprehensive time-calibrated phylogeny of tribe Miliuseae, especially focusing on the Desmopsis-Stenanona clade. We also perform ancestral area reconstructions to infer the biogeographic history of this group. Finally, we use ecological niche modeling, lineage distribution models, and niche overlap tests to assess whether geographic isolation and ecological specialization influenced the diversification of lineages within this clade. We reconstructed a monophyletic Miliuseae that is divided into two strongly supported clades: (i) a Sapranthus-Tridimeris clade and (ii) a Desmopsis-Stenanona clade. The colonization of the Neotropics and subsequent diversification of Neotropical Miliuseae seems to have been associated with the expansion of the boreotropical forests during the late Eocene and their subsequent fragmentation and southern displacement. Further speciation within Neotropical Miliuseae out of the Maya block seems to have occurred during the last 15 million years. Lastly, the geographic structuring of major lineages of the Desmopsis-Stenanona clade seems to have followed a climatic gradient, supporting the hypothesis that morphological differentiation between closely related species resulted from both long-term isolation between geographic ranges and adaptation to environmental conditions.

Chemical Composition and Bactericidal Activity of the Essential Oils of Four Species of Annonaceae Growing in Brazilian Amazon.

A study was conducted to determine the chemical composition and the antibacterial activity of essential oils from Bocageopsis multiflora (Mart.) R.E. Fr., Ephedranthus amazonicus R.E. Fr., Guatteria blepharophylla Mart. and Xylopia aromatica (Lam.) Mart . The essential oils were obtained from the leaves by hydrodistillation and analyzed by GC-FID and GC-MS. The chromatograms showed the predominance of sesquiterpenoids. Spathulenol was the major constituent of oils of B. inultiflora (20.3%), X aromatica (21.5%) and E. amazonicus (16.9%); followed by caryophyllene oxide of G. blepharophylla (55.7%). Other constituents with significant percentages were the sesquiterpenes P-bisabolene (11.9%) in the samples oil of B. multiflora, humulene epoxide 11 (16.3%) -of E. amazonicus, the monoterpenes trans-pinocarveol (10.2%) and dihydrocarveol (11.6%) of X aromatica. The essential oils of X. aromatica and G. blepharophylla showed strong activity against Gram-positive bacteria Streptococcus sanguinis by microdilution method. The antimicrobial activity against Staphylococcus aureus also was detected by G. blepharophylla essential oil.

7,7-Dimethylaporphine alkaloids from the stem of Guatteriopsis friesiana.

Phytochemical investigation of a methanolic extract of the stem of Guatteriopsis friesiana afforded two new 7,7-dimethylaporphine alkaloids, 6,6a-dihydrodemethoxyguadiscine (1) and guatteriopsiscine (3), together with demethoxyguadiscine (2), liriodenine (4), corypalmine (5), and coreximine (6). Their structures were elucidated on the basis of spectroscopic methods (UV, IR, EIMS, HRESIMS, 1D/2D NMR). The absolute configurations of 1 and 3 were determined from the circular dichroism curves. The presence of 7,7-dimethylaporphine alkaloids in this species is important for the chemotaxonomy of Guatteriopsis. Antimicrobial activity of compounds 1-5 was investigated, and 4 showed activity against Rhodococcus equi, with a MIC value of 10 microg x mL(-1).

A rapid diversification of rainforest trees (Guatteria; Annonaceae) following dispersal from Central into South America.

Several recent studies have suggested that a substantial portion of today's plant diversity in the Neotropics has resulted from the dispersal of taxa into that region rather than vicariance, but more data are needed to substantiate this claim. Guatteria (Annonaceae) is, with 265 species, the third largest genus of Neotropical trees after Inga (Fabaceae) and Ocotea (Lauraceae), and its widespread distribution and frequent occurrence makes the genus an excellent model taxon to study diversification patterns. This study reconstructed the phylogeny of Guatteria and inferred three major biogeographical events in the history of the genus: (1) a trans-oceanic Miocene migration from Central into South America before the closing of the Isthmus of Panama; (2) a major diversification of the lineage within South America; and (3) several migrations of South American lineages back into Central America via the closed Panamanian land bridge. Therefore, Guatteria is not an Amazonian centred-genus sensu Gentry but a major Miocene diversification that followed its dispersal into South America. This study provides further evidence that migration into the Neotropics was an important factor in the historical assembly of its biodiversity. Furthermore, it is shown that phylogenetic patterns are comparable to those found in Ocotea and Inga and that a closer comparison of these genera is desirable.