Guatteria

Abstract: Aim 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 by vicariance. In general, three routes have been documented for the dispersal of taxa onto the South American continent: (1) via the North Atlantic Land Bridge, (2) via the Bering Land Bridge, or (3) from Africa directly onto the continent. Here a species-rich genus of Neotropical lowland rain forest trees (Guatteria, Annonaceae) is used as a model to investigate these three hypotheses. Location The Neotropics. Methods The phylogenetic relationships within the long-branch clade of Annonaceae were reconstructed (using maximum parsimony, maximum likelihood and Bayesian inference) in order to gain insight in the phylogenetic position of Guatteria. Furthermore, Bayesian molecular dating and Bayesian dispersal‐vicariance (Bayes-DIVA) analyses were undertaken. Results Most of the relationships within the long-branch clade of Annonaceae were reconstructed and had high support. However, the relationship between the Duguetia clade, the Xylopia‐Artabotrys clade and Guatteria remained unclear. The stem node age estimate of Guatteria ranged between 49.2 and 51.3 Ma, whereas the crown node age estimate ranged between 11.4 and 17.8 Ma. For the ancestral area of Guatteria and its sister group, the area North America‐Africa was reconstructed in 99% of 10,000 DIVA analyses, while South America‐North America was found just 1% of the time. Main conclusions The estimated stem to crown node ages of Guatteria in combination with the Bayes-DIVA analyses imply a scenario congruent with an African origin followed by dispersal across the North Atlantic Land Bridge in the early to middle Eocene and further dispersal into North and Central America (and ultimately South America) in the Miocene. The phylogenetically and morphologically isolated position of the genus is probably due to extinction of the North American and European stem lineages in the Tertiary.

Abstract: Fractionation of Guatteria amplifolia yielded the alkaloids xylopine (1), nornuciferine (4), lysicamine (6), and laudanosine (5). Fractionation of Guatteria dumetorum yielded the alkaloids cryptodorine (2) and nornantenine (3). Compounds 1-4 demonstrated significant activity against Leishmania mexicana and L. panamensis. Xylopine (1) was among the most active compounds (LD 50 = 3 microM) and showed a 37-fold higher toxicity towards L. mexicana than macrophages, the regular host cells of Leishmania spp.

Abstract: Guatteria (Annonaceae) is with ca. 265 species one of the largest genera of Neotropical trees together with Inga and Ocotea. Use of Guatteria in evolutionary studies has been hampered by taxonomic problems caused by lack of morphological variability in the genus. This study focuses on molecular phylogenetic relationships within Guatteria and its satellites Guatteriopsis, Guatteriella and Heteropetalum, and implications of these relationships for classification and character evolution. Results show that Guatteriopsis, Guatteriella and Heteropetalum should be merged with Guatteria. Heteropetalum may be recognized at subgeneric level because of its aberrant morphology and Guatteriopsis and Guatteriella might be given sectional status. Most of the currently recognised sections in Guatteria are probably non-monophyletic. A completely new infrageneric classification of Guatteria would be premature, however, due to the lack of molecular and morphological synapomorphies to define the sections. Synapomorphies defining Guatteria s.str. probably evolved after divergence of several early branching lineages.