Roser Vilatersana

The cardueae (Compositae) revisited : Insights from its, trnL-trnF, and matK nuclear and chloroplast DNA analysis

Abstract The new outline of relationships in basal branches of the family Compositae Giseke confirms that the sister group to the tribe Cardueae Cass. are not Mutisieae Cass., but rather a group of African genera now classified as the tribe Tarchonantheae Kostel. This change implies that the monophyly of the Cardueae must be reassessed on a molecular basis. Moreover, new collections in recent years allow us to extend our sampling to 70 of the 74 genera of the tribe. We performed a new molecular study of the tribe using one nuclear region (ITS) and two chloroplastic markers (trnL-trnF and matK) in addition to a more appropriate outgroup. Our results confirm that the Cardueae is a natural group but indicate some changes in subtribal delineation: the subtribe Cardopatiinae Less. is recognized and some genera are moved to other subtribes (Myopordon Boiss., Nikitinia Iljin, Syreitschikovia Pavlov, and the Xeranthemum L. group). A recapitulation of a number of interesting questions that remain unresolved in the classification of some large genera is presented.

Generic delimitation and phylogeny of the Carduncellus-Carthamus complex (Asteraceae) based on ITS sequences

Within the Mediterranean complexCarduncellus-Carthamus, taxonomic classification has proven problematic. Numerous attempts to clarify the relative systematic boundaries have included splittingCarduncellus andCarthamus into several genera, but none of these proposed classifications have been generally accepted. For a comprehensive resolution of the relationships within this group, we used sequences of the Internal Transcribed Spacers (ITS) of nuclear ribosomal DNA. The results indicate that the complex should be classified into four genera:Carduncellus, Carthamus, Femeniasia andPhonus. The relationship between the western group (Carduncellus, Femeniasia andPhonus) and the eastern genusCarthamus are not resolved by analysis of ITS sequences, but the two groups are probably not close relatives. The ITS classifications corresponded with biogeography and less with morphological characters, which have also been the main source of confusion in traditional classifications. Most of the unusual morphological features in theCarduncellus-Carthamus complex appear to be reversals to ancestral character states.

Reconstructing the Evolution and Biogeographic History of Tribe Cardueae (Compositae)

UNLABELLED PREMISE OF THE STUDY Tribe Cardueae (thistles) forms one of the largest tribes in the family Compositae (2400 species), with representatives in almost every continent. The greatest species richness of Cardueae occurs in the Mediterranean region where it forms an important element of its flora. New fossil evidence and a nearly resolved phylogeny of Cardueae are used here to reconstruct the spatiotemporal evolution of this group. • METHODS We performed maximum parsimony and Bayesian phylogenetic inference based on nuclear ribosomal DNA and chloroplast DNA markers. Divergence times and ancestral area reconstructions for main lineages were estimated using penalized likelihood and dispersal-vicariance analyses, respectively, and integrated over the posterior distribution of the phylogeny from the Bayesian Markov chain Monte Carlo analysis to accommodate uncertainty in phylogenetic relationships. • KEY RESULTS The phylogeny shows that subtribe Cardopatiinae is sister to the remaining subtribes, and subtribes Carlininae and Echinopsinae appear as consecutive sister-clades to the Carduinae/Centaureinae. Tribe Cardueae is inferred to have originated around the Mid Eocene in West Asia, which is also the ancestral area of most subtribes within Cardueae. Diversification within each subtribe began during the Oligocene-Miocene period. • CONCLUSIONS Most diversification events within Cardueae are related to the continuous cycles of area connection and division between the Anatolian microplate and the western Mediterranean Basin during the Oligocene-Miocene and with the uplift of the Himalayan range from the Miocene onward. From these two regions, thistles dispersed and colonized the rest of the continents (e.g., the New World, Africa, and Australia), most likely during the colder Pliocene-Pleistocene period.

Evolution and biogeography of Centaurea section Acrocentron inferred from nuclear and plastid DNA sequence analyses

BACKGROUND AND AIMS Section Acrocentron of the genus Centaurea is one of the largest sections of Centaurea with approx. 100 species. The geographic distribution, centred in the Mediterranean, makes it an excellent example for studies of the biogeographic history of this biodiversity-rich region. METHODS Plastid (trnH-psbA) and nuclear (ITS and ETS) DNA sequence analysis was used for phylogenetic reconstruction. Ancestral biogeographic patterns were inferred by dispersal-vicariance analysis (DIVA). KEY RESULTS The resulting phylogeny has implications for the sectional classification of Acrocentron and confirms merging sect. Chamaecyanus into Acrocentron as a subsection. Previous suggestions of an eastern Mediterranean origin of the group are confirmed. The main centres of diversification established in previous studies are now strongly supported. Expansion of the group in two different radiations that followed patently diverse paths is inferred. CONCLUSIONS Radiation followed two waves, widely separated in time scale. The oldest one, from Turkey to Greece and the northern Balkans and then to North Africa and Iberia, should be dated at the end of the Miocene in the Messinian period. It reached the Iberian Peninsula from the south, following a route that is landmarked by several relictic taxa in Sicily and North Africa. A later radiation during the Holocene interglacial periods followed, involving species from the north of the Balkan Peninsula, along a Eurasian pathway running from Central Iberia to the steppes of Kazakhstan. A generalized pattern of reticulation is also evident from the results, indicating past contacts between presently separated species. Molecular data also confirmed the extent of hybridization within Acrocentron and were successful in reconstructing the paleogeography of the section.

On the origin of artichoke and cardoon from the Cynara gene pool as revealed by rDNA sequence variation

The evolutionary history of artichoke and cultivated cardoon and their relationships to wild allies of the genus Cynara are not fully understood yet. To try resolve the evolutionary patterns leading to the domestication of these two crops, a study of molecular evolution was undertaken. The species C. cardunculus, including artichoke, cultivated and wild cardoon, together with four wild Cynara species were taken into consideration. Internal (ITS) and external (ETS) rDNA transcribed spacers were used as markers of nuclear genome, the psbA-trnH spacer as a marker of chloroplast genome. Sequences were analysed using phylogenetic analysis packages. Molecular data indicate that the whole genus is quite recent and that the domestication of artichoke and cultivated cardoon, crops diverging for reproduction system and use, are independent events which diverge in time and space. As for wild Cynara species, an evolutionary pattern consistent with their present geographical distribution was hypothesized in relation to the climatic changes occurring in the Mediterranean during the last 20 millennia: C. humilis and C. cornigera appeared to have differentiated first, C. syriaca and C. baetica were differentiated in a second period, while C. cardunculus showed to be the most recent and plastic species. The high plasticity of C. cardunculus has not only allowed its nowadays wide distribution, but has also given the potential for domestication.

The polyploid series of Centaurea toletana: Glacial migrations and introgression revealed by nrDNA and cpDNA sequence analyzes

The polyploid series of Centaurea toletana comprises diploid, tetraploid, and hexaploid cytotypes. Previous studies suggested that the tetraploid was an autopolyploid, while the hexaploid was an allopolyploid and should be considered a different species, C. argecillensis. Sequencing of the ITS and rps4-trnT-trnL, ycf3-trnS, and rpL16 regions, and extensive cloning and sequencing of the ETS region have revealed that many diploid individuals and populations show different ribotypes, likely resulting from ancient hybridization events. Ribotypes found in the diploid populations are also present in tetraploid populations. The extreme difficulties in classifying the tetraploid as auto- or allopolyploid are discussed. The hexaploid C. argecillensis also shows many different ribotypes, including a ribotype not found in the diploids and making an autopolyploid origin unlikely. The pattern of introgression and gene flow implicates several species from the Iberian Peninsula and the High Atlas Mountains in Morocco as genetic donors in ancient hybridization events. This long-reaching network of hybridization may trace its origin to the climatic history of the western Mediterranean during the Neogene.

A first approach to the molecular phylogeny of the genus Echinops (Asteraceae): Sectional delimitation and relationships with the genus Acantholepis.

A first attempt to establish the phylogeny of the generaEchinops andAcantholepis has been carried out using the analysis of the internal transcribed spacers (ITS) sequences of the nuclear ribosomal DNA including 30Echinops species and the only species of the monotypicAcantholepis. The results of this analysis are discussed in the light of morphological and cytogenetic characters. The genusAcantholepis is placed in a robust clade withEchinops nanus, and together they appear in a basal position to other members ofEchinops. The ITS phylogeny and several other characters, such as chromosome number and nuclear DNA amount, do not agree with the sections currently recognized withinEchinops. Some groups are defined in the present approach, but further studies are necessary to reach a complete, stable and natural infrageneric classification of this genus.

Miocene-Pliocene speciation, introgression, and migration of Patis and Ptilagrostis (Poaceae: Stipeae).

Genetic interchange between American and Eurasian species is fundamental to our understanding of the biogeographical patterns, and we make a first attempt to reconstruct the evolutionary events in East Asia that lead to the origin and dispersal of two genera, Patis and Ptilagrostis. We conducted a molecular phylogenetic study of 78 species in the tribe Stipeae using four plastid DNA sequences (ndhF, rpl32-trnL, rps16-trnK, and rps16 intron) and two nuclear DNA sequences (ITS and At103). We use single copy nDNA gene At103 for the first time in the grasses to elucidate the evolutionary history among members of the Stipeae. Ampelodesmos, Hesperostipa, Oryzopsis, Pappostipa, Patis, and Stipa are found to be of multiple origins. Our phylograms reveal conflicting positions for Ptilagrostis alpina and Pt. porteri that form a clade with Patis coreana, P. obtusa, and P. racemosa in the combined plastid tree but are aligned with other members of Ptilagrostis in the ITS tree. We hypothesize that Ptilagrostis still retains the nucleotype of an extinct genus which transited the Bering land bridge from American origins in the late Miocene (minimum 7.35-6.37 mya) followed by hybridization and two plastid capture events with a Trikeraia-like taxon (7.96 mya) and para-Patis (between 5.32 and 3.76 mya). Ptilagrostis porteri and Patis racemosa then migrated to continental North America 1.7-2.9 mya and 4.3-5.3 mya, respectively.

Phylogeny of the Centaurea group (Centaurea, Compositae) - geography is a better predictor than morphology.

The Centaurea group is part of the Circum-Mediterranean Clade (CMC) of genus Centaurea subgenus Centaurea, a mainly Mediterranean plant group with more than 200 described species. The group is traditionally split on morphological basis into three sections: Centaurea, Phalolepis and Willkommia. This division, however, is doubtful, especially in light of molecular approaches. In this study we try to resolve this phylogenetic problem and to consolidate the circumscription and delimitation of the entire group against other closely related groups. We analyzed nuclear (internal transcribed spacer of the ribosomal genes) and chloroplast (rpl32-trnL intergenic spacer) DNA regions for most of the described species of the Centaurea group using phylogenetic and network approaches, and we checked the data for recombination. Phylogeny was used to reconstruct the evolution of the lacerate-membranaceous bract appendages using parsimony. The magnitude of incomplete lineage sorting was tested estimating the effective population sizes. Molecular dating was performed using a Bayesian approach, and the ancestral area reconstruction was conducted using the Dispersal-Extinction-Cladogenesis method. Monophyly of the Centaurea group is confirmed if a few species are removed. Our results do not support the traditional sectional division. There is a high incongruence between the two markers and between genetic data and morphology. However, there is a clear relation between geography and the structure of the molecular data. Diversification in the Centaurea group mainly took place during the Pliocene and Pleistocene. The ancestral area infered for the Circum-Mediterranean Clade of Centaurea is the Eastern Mediterranean, whereas for the Centaurea group it is most likely NW-Africa. The large incongruencies, which hamper phylogenetic reconstruction, are probably the result of introgression, even though the presence of incomplete lineage sorting as an additional factor cannot be ruled out. Convergent evolution of morphological traits may have led to incongruence between morphology-based, traditional systematics and molecular results. Our results also cast major doubts about current species delimitation.

Molecular Phylogeny of the Genus Ptilostemon (Compositae: Cardueae) and Its Relationships with Cynara and Lamyropsis

Abstract Ptilostemon is a fine example of the representatives of the eastern groups of the Cardueae that have diversified in the western Mediterranean. Relationships to Cynara, which exhibits a similar distribution, and Lamyropsis, which is morphologically closer according to previous studies, are investigated using Bayesian analysis of DNA sequences of the plastid intergenic spacer ycf3-trnS and two nuclear regions, the ETS and ITS spacers. The sectional classification and biogeography of Ptilostemon are also revised in the light of the molecular phylogeny Our results suggest that Cynara is the most plausible sister genus to Ptilostemon. Some paralogous copies of the ETS region found among species of the three genera by cloning are interpreted as incomplete lineage sorting of ancestral polymorphisms. The current sectional classification of Ptilostemon shows excessive fragmentation, which does not agree with our phylogeny, and therefore a more synthetic classification is proposed. The present distribution of Ptilostemon indicates that there were two colonization events in the western Mediterranean region, paralleling a similar pattern of successive waves already suggested for Cynara.