Plant dispersal across the tropical Atlantic by wind and sea currents

This review brings together evidence on the monophyly and ages of angiosperm lineages ranging across the tropical Atlantic with data on the direction, strength, and speed of sea currents and wind jets across that ocean. Mainly for pragmatic reasons (data availability), the focus is on genera, which introduces a rank-based constraint into the analysis. However, trans-Atlantic disjunctions at the genus level seemed more likely to be attributable to long-distance dispersal than those involving families or species; family-level disjunctions often may date back to the breakup of Africa and South America, and species-level disjunctions often may be anthropogenic. At least 110 genera (listed in this article) contain species on both sides of the tropical Atlantic. Molecular phylogenies and age estimates from molecular clocks are available for 11 disjunct genera, tribes, and species. Inferred directions and modes of dispersal can be related parsimoniously to water currents between Africa and South America and to exceptional westerly winds blowing from northeastern Brazil to northwest Africa. Based on diaspore morphology and inferred dispersal biology in the 110 genera, trans-Atlantic dispersal by water (in both directions) appears more common than dispersal by wind or on birds. Wind dispersal appears to have occurred in the direction from South America to West Africa but rarely in the opposite direction

Detection of Laplace-resonant three-planet systems from transit timing variations

Transit timing variations (TTVs) are useful to constrain the existence of perturbing planets, especially in resonant systems where the variations are strongly enhanced. Here we focus on Laplace-resonant three-planet systems, and assume the inner planet transits the star. A dynamical study is performed for different masses of the three bodies, with a special attention to terrestrial planets. We consider a maximal time-span of ~ 100 years and discuss the shape of the inner planet TTVs curve. Using frequency analysis, we highlight the three periods related to the evolution of the system: two periods associated with the Laplace-resonant angle and the third one with the precession of the pericenters. These three periods are clearly detected in the TTVs of an inner giant planet perturbed by two terrestrial companions. Only two periods are detected for a Jupiter-Jupiter-Earth configuration (the ones associated with the giant interactions) or for three terrestrial planets (the Laplace periods). However, the latter system can be constrained from the inner planet TTVs. We finally remark that the TTVs of resonant three or two Jupiter systems mix up, when the period of the Laplace resonant angle matches the pericenter precession of the two-body configuration. This study highlights the importance of TTVs long-term observational programs for the detection of multiple-planet resonant systems.Comment: 8 pages, 8 figures, accepted in MNRA

New Species of Siparuna (Siparunaceae) III

Three new species of Siparuna (Siparunaceae) are described, illustrated, and placed in a phylogenetic context: S. gentryana from western Ecuador and adjacent Colombia, S. lozaniana from the western Andes in Colombia, and S. vasqueziana from Amazonian Peru. In addition, Siparuna calantha from the Sierra Nevada de Santa Marta, originally described by Janet Perkins as a variety of a Mexican entity, is raised to species rank because its broader leaves and more numerous carpels readily distinguish it from its apparent closest relative, a species from the western Colombian Andes. Each of the species is known from several collections, which allowed the secure matching of sexual morphs in the three that are dioecious

New Species of Siparuna (Siparunaceae) IV

A new species of Siparuna (Siparunaceae), S. ficoides, is described, illustrated, and placed in a phylogenetic context based on morphological and DNA sequence data. The species, which is a monoecious subcanopy tree, is known from three collections made near Manaus, Brazil (two from the same tree), and one in the state of Bolivar, Venezuela.Se describe y se ilustra una nueva especie de Siparuna (Siparunaceae), S. ficoides, ademas se la ubica en un contexto filogenetico basado en datos morfologicos y en sequencias de DNA. Esta nueva especie es un arbol monoico de subdosel, de la cual se han registrado tres colecciones cerca de Manaos, Brasil (dos del mismo arbol) y una coleccion en el Estadod e Bolivar, Venezuela

New species and new combinations in Sonerila and Phyllagathis (Melastomataceae) from Thailand

While revising the Melastomataceae for the Flora of Thailand, we discovered two new species of Sonerila, as well as the need for transferring two species of Tylanthera endemic to Thailand into Phyllagathis. Sonerila urceolata and S. loeiensis are endemic to the southeast and the northeast of Thailand, respectively. The first is allied to the widespread S. erecta Jack, from which it differs mainly in the strongly urceolate capsule and the sessile fruit placenta; the second is distinguished from other acaulescent species of Sonerila by its extremely long-petiolate large leaves and long-pedunculate inflorescence. The new combinations, Phyllagathis tuberosa (Hansen) Cellinese & Renner and P. siamensis Cellinese & Renner nom. nov., are made because both taxa lie inside the morphologic and phylogenetic bounds of Phyllagathis

Coccinia intermedia

Nuclear and plastid sequences from two individuals of a suspected new species of Coccinia from West Africa were added to an available molecular phylogeny for the remaining 27 species of the genus. Phylogenetic analyses of these data indicate the new species' monophyletic status and closest relatives. Based on four fertile collections, we here describe and illustrate Coccinia intermedia Holstein. We also provide a key to the Coccinia species of West Africa and map their distributions

Resurrection of the genus Staphisagria J. Hill, sister to all the other Delphinieae (Ranunculaceae)

Molecular sequence data show that the three species of Delphinium subg. Staphisagria (J. Hill) Peterm. form the sister clade to Aconitum L., Aconitella Spach, Consolida (DC.) S.F. Gray, and all remaining species of Delphinium L. To account for this finding we resurrect Staphisagria J. Hill (1756). Names in Staphisagria are available for two of the species. We here make the required new combination for the third species, Staphisagria picta (Willd.) F. Jabbour, provide a key to the species, and illustrate one of them

Large Hadron Collider constraints on a light baryon number violating sbottom coupling to a top and a light quark

We investigate a model of R-parity violating (RPV) supersymmetry in which the right-handed sbottom is the lightest supersymmetric particle, and a baryon number violating coupling involving a top is the only non-negligible RPV coupling. This model evades proton decay and flavour constraints. We consider in turn each of the couplings lambda"_{313} and lambda"_{323} as the only non-negligible RPV coupling, and we recast two recent Large Hadron Collider (LHC) measurements and searches (CMS top transverse momentum p_T(t) spectrum and ATLAS multiple jet resonance search) in the form of constraints on the mass-coupling parameter planes. We delineate a large region in the parameter space of the mass of the sbottom (m_{b_R}) and the lambda"_{313} coupling that is ruled out by the measurements, as well as a smaller region in the parameter space of m_{b_R} and lambda"_{323}. A certain region of the m_{b_R}-lambda"_{313} parameter space was previously found to successfully explain the anomalously large ttbar forward backward asymmetry measured by Tevatron experiments. The entire region is excluded at the 95% CL by CMS measurements of the top p_T spectrum. We also present p_T(ttbar) distributions of the forward-backward asymmetry for this model.Comment: 9 pages, 9 figures. v2 has minor corrections, in part due to extra diagrams at order alpha_s^2 lamba''^

The deepest splits in Chloranthaceae as resolved by chloroplast sequences

Evidence from the fossil record, comparative morphology, and molecular phylogenetic analyses indicates that Chloranthaceae are among the oldest lineages of flowering plants alive today. Their four genera (ca. 65 species) today are disjunctly distributed in the Neotropics, China, tropical Asia, and Australasia, with a single species in Madagascar but none in mainland Africa. In the Cretaceous, Chloranthaceae occurred in much of Laurasia as well as Africa, Australia, and southern South America. We used DNA sequence data from the plastid rbcL gene, the rpl20-rps12 spacer, the trnL intron, and the trnL-F spacer to evaluate intra-Chloranthaceae relationships and geographic disjunctions. In agreement with earlier analyses, Hedyosmum was found to be sister to the remaining genera, followed by Ascarina and Chloranthus + Sarcandra. Bayesian and parsimony analyses of the combined data yielded resolved and well-supported trees except for polytomies among Andean Hedyosmum and Madagascan-Australasian-Polynesian Ascarina. The sole Asiatic species of Hedyosmum, Hedyosmum orientale from Hainan, China, was sister to Caribbean and Neotropical species. Likelihood ratio tests on the rbcL data set did not reject the assumption of a clock as long as the long-branched outgroup Canella was excluded. Two alternative fossil calibrations were used to convert genetic distances into absolute ages. Calibrations with Hedyosmum-like flowers from the Barremian-Aptian or Chloranthus-like androecia from the Turonian yielded substitution rates that differed by a factor of two, illustrating a perhaps unsolvable problem in molecular clock–based studies that use several calibration fossils. The alternative rates place the onset of divergence among crown group (extant) species of Hedyosmum at 60 or 29 Ma, between the Paleocene and the Oligocene; that among extant Chloranthus at 22 or 11 Ma; and that among extant Ascarina at 18 or 9 Ma, implying long-distance dispersal between Madagascar and Australasia-Polynesia

Circumscription and phylogeny of the Laurales

The order Laurales comprises a few indisputed core constituents, namely Gomortegaceae, Hernandiaceae, Lauraceae, and Monimiaceae sensu lato, and an equal number of families that have recently been included in, or excluded from, the order, namely Amborellaceae, Calycanthaceae, Chloranthaceae, Idiospermaceae, and Trimeniaceae. In addition, the circumscription of the second largest family in the order, the Monimiaceae, has been problematic. I conducted two analyses, one on 82 rbcL sequences representing all putative Laurales and major lineages of basal angiosperms to clarify the composition of the order and to determine the relationships of the controversal families, and the other on a concatenated matrix of sequences from 28 taxa and six plastid genome regions (rbcL, rpl16, trnT-trnL, trnL-trnF, atpB-rbcL, and psbA-trnH) that together yielded 898 parsimony-informative characters. Fifteen morphological characters that play a key role in the evolution and classification of Laurales were analyzed on the most parsimonious molecular trees as well as being included directly in the analysis in a total evidence approach. The resulting trees strongly support the monophyly of the core Laurales (as listed above) plus Calycanthaceae and Idiospermaceae. Trimeniaceae form a clade with Illiciaceae, Schisandraceae, and Austrobaileyaceae, whereas Amborellaceae and Chloranthaceae represent isolated clades that cannot be placed securely based on rbcL alone. Within Laurales, the deepest split is between Calycanthaceae (including Idiospermaceae) and the remaining six families, which in turn form two clades, the Siparunaceae (Atherospermataceae-Gomortegaceae) and the Hernandiaceae (Monimiaceae s.str. [sensu stricto]-Lauraceae). Monimiaceae clearly are polyphyletic as long as they include Atherospermataceae and Siparunaceae. Several morphological character state changes are congruent with the molecular tree: (1) Calycanthaceae have disulculate tectate-columellate pollen, while their sister clade has inaperturate thin-exined pollen, with the exception of Atherospermataceae, which have columellate but meridionosulcate or disulcate pollen. (2) Calycanthaceae have two ventral ovules while their sister clade has solitary ovules. Within this sister clade, the Hernandiaceae (Lauraceae-Monimiaceae) have apical ovules, while the Siparunaceae (Atherospermataceae-Gomortegaceae) are inferred to ancestrally have basal ovules, a condition lost in Gomortega, the only lauralean genus with a syncarpous ovary. (3) Calycanthaceae lack floral nectaries (except for isolated nectarogeneous fields on the inner tepals), while their sister clade ancestrally has paired nectar glands on the filaments. Filament glands were independently lost in higher Monimiaceae and in Siparunaceae concomitant with pollinator changes away from nectar-foraging flies and bees to non-nectar feeding beetles and gall midges. (4) Disporangiate stamens with anthers dehiscing by two apically hinged valves are ancestral in Siparunaceae-(Atherospermataceae- Gomortegaceae) and evolved independently within Hernandiaceae and Lauraceae. Depending on the correct placement of Calycanthaceae-like fossil flowers, tetrasporangiate anthers with valvate dehiscence (with the valves laterally hinged) may be ancestral in Laurales and lost in modern Calycanthaceae and Monimiaceae