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PREMISE OF THE STUDY: Long-distance dispersal can affect speciation processes in two opposing ways. Dispersal can promote geographic isolation or it can bring together geographically distant and distantly related genotypes, thus counteracting local differentiation. We used the Gulf Coast of North America (GC), a "hot spot" of reed diversity and evolutionary dynamics, as a model system to study the diversification processes within the invasive, cosmopolitan, polyploid grass Phragmites. METHODS: Genetic diversity was studied using collections representing all species of the genus and from all continents (except Antarctica). A range of molecular markers, including chloroplast and nuclear sequences, microsatellites, and AFLPs, was analyzed to detect DNA variation from the population to the species level and to infer phylogenetic relationships across continents. KEY RESULTS: An interspecific hybrid, Phragmites mauritianus × P. australis, and four P. australis cp-DNA haplotypes from Africa, Europe, and North America have been dispersed to the GC and interbreed with each other. CONCLUSIONS: Long-distance dispersal and weak breeding barriers appear to be recurring phenomena, not only in the GC, but worldwide. We present data strongly suggesting that interspecific hybridization and introgression among different Phragmites species take place and appear to have contributed significantly to the diversification processes within the genus. Hence, the application of traditional species concepts within Phragmites might be inappropriate.

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PREMISE OF THE STUDY: The clusioid clade includes five families (i.e., Bonnetiaceae, Calophyllaceae, Clusiaceae s.s., Hypericaceae, and Podostemaceae) represented by 94 genera and ≈1900 species. Species in this clade form a conspicuous element of tropical forests worldwide and are important in horticulture, timber production, and pharmacology. We conducted a taxon-rich multigene phylogenetic analysis of the clusioids to clarify phylogenetic relationships in this clade. METHODS: We analyzed plastid (matK, ndhF, and rbcL) and mitochondrial (matR) nucleotide sequence data using parsimony, maximum likelihood, and Bayesian inference. Our combined data set included 194 species representing all major clusioid subclades, plus numerous species spanning the taxonomic, morphological, and biogeographic breadth of the clusioid clade. KEY RESULTS: Our results indicate that Tovomita (Clusiaceae s.s.), Harungana and Hypericum (Hypericaceae), and Ledermanniella s.s. and Zeylanidium (Podostemaceae) are not monophyletic. In addition, we place four genera that have not been included in any previous molecular study: Ceratolacis, Diamantina, and Griffithella (Podostemaceae), and Santomasia (Hypericaceae). Finally, our results indicate that Lianthus, Santomasia, Thornea, and Triadenum can be safely merged into Hypericum (Hypericaceae). CONCLUSIONS: We present the first well-resolved, taxon-rich phylogeny of the clusioid clade. Taxon sampling and resolution within the clade are greatly improved compared to previous studies and provide a strong basis for improving the classification of the group. In addition, our phylogeny will form the foundation for our future work investigating the biogeography of tropical angiosperms that exhibit Gondwanan distributions.

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Phylogenetic relationships in Inuleae subtribe Inulinae (Asteraceae) were investigated. DNA sequence data from three chloroplast regions (ndhF, trnL-F and psbA-trnH) and the nuclear ribosomal internal transcribed spacer (ITS) region were analysed separately and in combination using parsimony and Bayesian inference. A total of 163 ingroup taxa were included, of which 60 were sampled for all four markers. Conflicts between chloroplast and nuclear data were assessed using partitioned Bremer support (PBS). Rather than averaging PBS over several trees from constrained searches, individual trees were considered by evaluating PBS ranges. Criteria to be used in the detection of a significant conflict between data partitions are proposed. Three nodes in the total data tree were found to encompass significant conflict that could result from ancient hybridization. Neither of the large, heterogeneous and widespread genera Inula and Pulicaria is monophyletic. A monophyletic group ("the Inula complex") that comprises all species of Inula includes also Telekia, Carpesium, Chrysophthalmum, Rhanteriopsis, Amblyocarpum, and Pentanema sensu stricto. Two species of Pentanema were found to be closer to Blumea (including Blumeopsis and Merrittia) and Caesulia. The monophyletic "Pulicaria complex" includes all taxa with heteromorphic pappus. Within this group, Francoeuria is distinct from Pulicaria and merits recognition as a separate genus. © The Willi Hennig Society 2009.

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BACKGROUND AND AIMS: A report is made on a new species of Clusia related to C. sellowiana that dominates the vegetation of the Nouragues inselberg in French Guiana. The focus is on the pollination biology and on the remarkable relationship of this plant species to Amazonina platystylata, its cockroach pollinator. This appears to be only the second record of pollination by cockroaches. METHODS: Pollination ecology was investigated by combining morphological studies, field observations and additional experiments. Floral scent was analysed by gas chromatography-mass spectrometry. The role of acetoin, the major component of the scent of this species of Clusia, in attracting pollinators was examined in field attraction experiments. The ability of cockroaches to perceive acetoin was investigated by electroantennography (EAG). KEY RESULTS: The Clusia species studied produces seeds only sexually. Its nocturnal flowers are visited by crickets, ants, moths and cockroaches. A species of cockroach, Amazonina platystylata, is the principal pollinator. The reward for the visit is a liquid secretion produced by tissues at the floral apex and at the base of the ovary. Although the cockroaches have no structures specialized for pollen collection, their body surface is rough enough to retain pollen grains. The cockroaches show significant EAG reactions to floral volatiles and acetoin, suggesting that the floral scent is a factor involved in attracting the cockroaches to the flowers. CONCLUSIONS: The results suggest that the plant-cockroach interaction may be quite specialized and the plant has probably evolved a specific strategy to attract and reward its cockroach pollinators. Acetoin is a substance involved in the chemical communication of several other cockroach species and it seems plausible that the plant exploits the sensitivity of cockroaches to this compound to attract them to the flowers as part of the pollination syndrome of this species.

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The Ceroxyloideae is a small but heterogeneous subfamily of palms (Arecaceae, Palmae). It includes a Caribbean lineage (tribe Cyclospathae), a southern hemisphere disjunction (tribe Ceroxyleae), and an amphi-Andean element (tribe Phytelepheae), until recently considered a distinct subfamily (Phytelephantoideae) due to its highly derived morphology. A variety of hypotheses have been proposed to account for the biogeography of the subfamily, involving Gondwanan vicariance, austral interplate dispersal from South America to Australia via Antarctica, Andean orogeny, and Pleistocene refuges. We assessed the systematic classification and biogeography of the group based on a densely sampled phylogeny using >5.5kb of DNA sequences from three plastid and two nuclear genomic regions. The subfamily and each of its three tribes were resolved as monophyletic with high support. Divergence time estimates based on penalized likelihood and Bayesian dating methods indicate that Gondwanan vicariance is highly unlikely as an explanation for basic disjunctions in tribe Ceroxyleae. Alternative explanations include a mid-Tertiary trans-Atlantic/trans-African dispersal track and the "lemurian stepping stones" hypothesis. Austral interplate dispersal of Oraniopsis to Australia could have occurred, but apparently only in the mid-Eocene/early Oligocene interval after global cooling had begun. Our data do not support Pleistocene climatic changes as drivers for speciation in the Andean-centered Phytelepheae as previously proposed. Radiation in this tribe coincides largely with the major uplift of the Andes, favoring Andean orogeny over Pleistocene climatic changes as a possible speciation-promoting factor in this tribe.

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Chloroplast DNA sequences and microsatellites are useful tools for phylogenetic as well as population genetic analyses of plants. Chloroplast microsatellites tend to be less variable than nuclear microsatellites and therefore they may not be as powerful as nuclear microsatellites for within-species population analysis. However, chloroplast microsatellites may be useful for phylogenetic analysis between closely related taxa when more conventional loci, such as ITS or chloroplast sequence data, are not variable enough to resolve phylogenetic relationships in all clades. To determine the limits of chloroplast microsatellites as tools in phylogenetic analyses, we need to understand their evolution. Thus, we examined and compared phylogenetic relationships of species within the genus Clusia, using both chloroplast sequence data and variation at seven chloroplast microsatellite loci. Neither ITS nor chloroplast sequences were variable enough to resolve relationships within some sections of the genus, yet chloroplast microsatellite loci were too variable to provide any useful phylogenetic information. Size homoplasy was apparent, caused by base substitutions within the microsatellite, base substitutions in the flanking regions, indels in the flanking regions, multiple microsatellites within a fragment, and forward/reverse mutations of repeat length resulting in microsatellites of identical base composition that were not identical by descent.

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Scaevola, the only genus of Goodeniaceae that has extensively radiated outside of Australia, has dispersed throughout the Pacific Basin, with a few species reaching the tropical coastal areas of the Atlantic and Indian Oceans. Five Australian and most of the non-Australian species are placed in Scaevola section Scaevola based on their fleshy fruits, indeterminate inflorescences, and more arborescent habits. Analyses of ITS sequence data demonstrate that Scaevola is a monophyletic group if S. collaris is excluded and Diaspasis filifolia is included. The genus is Australian in origin, but there have been at least six separate dispersal events from Australia. Four of these dispersals each resulted in single extra-Australian species. The remaining two were followed by radiations that gave rise to large groups, each including one of the widespread strand species, S. taccada and S. plumieri. Remarkably, three of the six dispersals established species on the remote Hawaiian Archipelago, representing at present the largest number of colonizations by any flowering plant genus to these islands.