No abstract

The 'didymocarpoid Gesneriaceae' (traditional subfam. Cyrtandroideae excluding Epithemateae) are the largest group of Old World Gesneriaceae, comprising 85 genera and 1800 species. We attempt to resolve their hitherto poorly understood generic relationships using three molecular markers on 145 species, of which 128 belong to didymocarpoid Gesneriaceae. Our analyses demonstrate that consistent topological relationships can be retrieved from data sets with missing data using subsamples and different combinations of gene sequences. We show that all available classifications in Old World Gesneriaceae are artificial and do not reflect natural relationships. At the base of the didymocarpoids are grades of clades comprising isolated genera and small groups from Asia and Europe. These are followed by a clade comprising the African and Madagascan genera. The remaining clades represent the advanced Asiatic and Malesian genera. They include a major group with mostly twisted capsules. The much larger group of remaining genera comprises exclusively genera with straight capsules and the huge genus Cyrtandra with indehiscent fruits. Several genera such as Briggsia, Henckelia, and Chirita are not monophyletic; Chirita is even distributed throughout five clades. This degree of incongruence between molecular phylogenies, traditional classifications, and generic delimitations indicates the problems with classifications based on, sometimes a single, morphological characters.

Summary• Polyploidization and chromosomal rearrangements are recognized as major forces in plant evolution. Their role is investigated in the disjunctly distributed northern hemisphere Hepatica (Ranunculaceae).• Chromosome numbers, karyotype morphology, banding patterns, 5S and 35S rDNA localization in all known species were investigated and interpreted in a phylogenetic context established from nuclear internal transcribed spacer (ITS) and plastid matK sequences.• All species had a chromosome base number of x = 7. The karyotype was symmetric and showed little variation among diploids with one locus each of 5S and 35S rDNA, except for interpopulational variation concerning 35S rDNA loci number and localization in H. asiatica. Tetraploids exhibited chromosomal changes, including asymmetry and/or loss of rDNA loci. Nuclear and plastid sequences resulted in incongruent topologies because of the positions of some tetraploid taxa. The diversification of Hepatica occurred not earlier than the Pliocene.• Genome restructuring, especially involving 35S rDNA, within a few million yr or less characterizes evolution of both auto-and allopolyploids and of the diploid species H. asiatica, which is the presumptive ancestor of two other diploid species.

This study was undertaken to better understand Allium infrageneric taxonomy, character evolution, species diversification, and patterns of radiation in disjunct species between the New and Old World using morphological and molecular data. Taxonomic sampling focused on northeastern Asian (mainly Korean and northeastern Chinese) and representative disjunct northern North American (Canadian) species. Pistil and seed testa morphology was investigated using light and scanning electron microscopy, respectively. These characters were useful to assess degree of relationship at different taxonomic levels in Allium. Phylogenetic studies included nrDNA ITS and cpDNA trnL-trnF sequence data analyzed using maximum parsimony approaches. Our molecular phylogeny recovers a similar topology to that published in recent studies and confirms three major evolutionary lines and patterns of radiation regarding the ancestors of subgenera Amerallium and Anguinum in the genus. The northeastern Asian and northern North American disjunction in this genus is inferred to be the result of multiple intercontinental migrations. Seed testa sculpture attributes in combination with seed shape provide key characters to distinguish Allium's major clades in the molecular phylogeny. The two types of ovarian processes, basal hood-like and apical crest-like in disjunct Old and New World species, respectively, are newly derived characters in each continent. Most infrageneric Allium groups are monophyletic, while subgenus Cepa is polyphyletic.Résumé : Les auteurs ont étudié les Allium afin de mieux en comprendre la taxonomie infragénérique, l'évolution des caractè-res, la diversification des espèces et les partons de radiation chez les espèces disjointes du Nouveau et de l'Ancien Monde, en utilisant des données morphologiques et moléculaires. Ils ont centré l'échantillonnage taxonomique sur l'Asie du Nord-est (surtout en Corée et au nord-est de la Chine) ainsi que des espèces disjointes de l'Amérique du Nord (Canada). Ils ont examiné la morphologie des pistils et des téguments de la graine, en utilisant la microscopie photonique et électronique par balayage, respectivement. Ces caractères se sont avérés utiles pour évaluer le degré de relation aux différents degrés taxonomiques des Allium. Les études phylogénétiques ont porté sur les données des séquences des ITS du nrADN et cpADN trnL-trnF, analysées en utilisant des approches de parcimonie maximum. La phylogénie moléculaire obtenue par les auteurs conduit à une topologie similaire à celle publiée dans de récentes études et confirme trois lignées évolutives et patrons de radiation en ce qui a trait aux ancêtres des sous-genres Amerallium et Anguinum, dans le genre. On déduit que la disjonction du genre entre le Nord-est asiatique et le Nord-Américain serait le résultat de multiples migrations intercontinentales. Les attributs sculpturaux des téguments combinés avec la forme des graines fournissent des caractères clés pour distinguer les principaux clades provenant de la phylogénie moléculaire. Les deux ty...