a b s t r a c tWe reconstruct here the spatial and temporal evolution of the Campanula alliance in order to better understand its evolutionary history. To increase phylogenetic resolution among major groups (Wahlenbergieae-Campanuleae), new sequences from the rbcL region were added to the trnL-F dataset obtained in a previous study. These phylogenies were used to infer ancestral areas and divergence times in Campanula and related genera using a Bayesian approach to molecular dating and dispersal-vicariance analyses that takes into account phylogenetic uncertainty. The new phylogenetic analysis confirms Platycodoneae as the sister group of Wahlenbergieae-Campanuleae, the two last ones inter-graded into a well-supported clade. Biogeographic and dating analyses suggest that Western Asia and the Eastern Mediterranean have played a major role as centers of migration and diversification within the Campanula alliance, probably in relation to the intense orogenic activity that took place in this region during the Late Neogene, and that could have promoted isolation and allopatric speciation within lineages. Diversification rates within several Campanula lineages would have increased at the end of the Miocene, coinciding with the Messinian Stage. Strong selective pressures from climate changes and the expansion of mountainous regions during this period are suggested to explain the adaptation to drought, cold or disturbed environments observed in many Campanula species. Several independent long-distance dispersal events to North America are inferred within the Rapunculus clade, which seem to be related to high ploidy levels.

No abstract

No abstract

Disentangling species boundaries and phylogenetic relationships within recent evolutionary radiations is a challenge due to the poor morphological differentiation and low genetic divergence between species, frequently accompanied by phenotypic convergence, interspecific gene flow and incomplete lineage sorting. Here we employed a genotyping-by-sequencing (GBS) approach, in combination with morphometric analyses, to investigate a small western Mediterranean clade in the flowering plant genus Linaria that radiated in the Quaternary. After confirming the morphological and genetic distinctness of eight species, we evaluated the relative performances of concatenation and coalescent methods to resolve phylogenetic relationships. Specifically, we focused on assessing the robustness of both approaches to variations in the parameter used to estimate sequence homology (clustering threshold). Concatenation analyses suffered from strong systematic bias, as revealed by the high statistical support for multiple alternative topologies depending on clustering threshold values. By contrast, topologies produced by two coalescent-based methods (NJ$_{\mathrm{st}}$, SVDquartets) were robust to variations in the clustering threshold. Reticulate evolution may partly explain incongruences between NJ$_{\mathrm{st}}$, SVDquartets and concatenated trees. Integration of morphometric and coalescent-based phylogenetic results revealed (i) extensive morphological divergence associated with recent splits between geographically close or sympatric sister species and (ii) morphological convergence in geographically disjunct species. These patterns are particularly true for floral traits related to pollinator specialization, including nectar spur length, tube width and corolla color, suggesting pollinator-driven diversification. Given its relatively simple and inexpensive implementation, GBS is a promising technique for the phylogenetic and systematic study of recent radiations, but care must be taken to evaluate the robustness of results to variation of data assembly parameters.

Classification of the tribe Cardueae in natural subtribes has always been a challenge due to the lack of support of some critical branches in previous phylogenies based on traditional Sanger markers. With the aim to propose a new subtribal delimitation, we applied a Hyb-Seq approach to a set of 76 Cardueae species representing all the subtribes and informal groups defined in the tribe, targeting 1061 nuclear conserved orthology loci (COS) designed for Compositae and obtaining chloroplast coding regions as byproduct of off-target reads. For the extraction of target nuclear data, we used two strategies, PHYLUCE and HybPiper, and 776 and 1055 COS loci were recovered with each of them, respectively. Additionally, 87 chloroplast genes were assembled and annotated. With the three datasets, phylogenetic relationships within the tribe were reconstructed under approaches of concatenation (using supermatrices as input for maximum likelihood analysis with RAxML) and coalescence (species tree estimated with ASTRAL based on the individual gene trees of each COS locus). The phylogenetic analyses of the nuclear datasets fully resolved virtually all nodes with very high support. Although nuclear and plastid tree topologies are highly congruent, they still present some incongruences, which are shortly discussed. On the basis of the phylogenies obtained, we propose a new taxonomic scheme of 12 monophyletic and morphologically consistent subtribes: Carlininae, Cardopatiinae, Echinopsinae, Dipterocominae (new), Xerantheminae (new), Berardiinae (new), Staehelininae (new), Onopordinae (new), Carduinae (redelimited), Arctiinae (new), Saussureinae (new), and Centaureinae. Another main key result of the study was the high resolution recovered at the backbone of the Cardueae tree, which led to obtain better inter-subtribal relationships. Using as tree base the nuclear HybPiper phylogeny, we updated the temporal framework for the origin and diversification of the tribe and subtribes. Overall, the power of Hyb-Seq is demonstrated to solve relationships traditionally suggested by morphology but never recovered with support using Sanger sequencing of a few DNA markers.

The internal transcribed spacers ITS1 and ITS2 of the nuclear rDNA were sequenced for 41 Helichrysum species (Gnaphalieae), focusing on the Mediterranean group of species, together with eight representatives of other genera of the Gnaphalieae, in order to check the hypothesised monophyly of the Mediterranean Helichrysum group and the correspondence of the sequence data with its traditional sectional classification. The cladistic analysis of sequence data supports monophyly of the Mediterranean Helichrysum excluding H. frigidum and H. montelinasanum. The traditional classification of the Mediterranean species into two sections, Helichrysum and Virginea, is not supported, whereas a group constituted by species from the west Mediterranean area is shown as a moderately supported monophyletic clade in the strict consensus tree. Other results also show and confirm the complexity, still not satisfactorily resolved, of the Helichrysum generic delimitation: Pseudognaphalium luteoalbum appears merged in Helichrysum whereas Helichrysum dasyanthum appears more related to Anaxeton laeve than to any Helichrysum species.

A taxonomic revision of Helichrysum sect. Stoechadina, a section with a Mediterranean distribution, is presented. Taxonomic, nomenclatural, morphological, chromosomal, geographical, and ecological data are provided for each taxon. Eleven taxa are recognized, two lectotypifications are proposed, and a taxonomic key and a sectional description are included. The following new combinations are proposed: Helichrysum italicum subsp. siculum (Jord. & Fourr.) Galbany, L. Sáez & Benedí comb. nov. and Helichrysum italicum subsp. picardii (Boiss. & Reut.) Galbany, L. Sáez & Benedí comb. nov.

The genus Helichrysum has 500-600 species in Africa, Madagascar, the Mediterranean basin, Macaronesia, western and central Asia, and India. The aims of this study are to confirm the exclusion of Castroviejoa from Helichrysum, to elucidate the origin of the Macaronesian endemics, to confirm the monophyly of the Mediterranean-Asiatic group, and, within this group, to contrast molecular data with sectional classification and to provide insight into trends in character evolution and biogeography. To address these issues, ITS and ETS sequences were used in phylogenetic analyses. Results show that Castroviejoa is excluded from Helichrysum. The phylogeny obtained suggests a southern African origin for Helichrysum and several subsequent migrations throughout the African continent. The species from the Canary Islands do not form a monophyletic clade, suggesting that at least two independent colonization events occurred. Helichrysum makranicum, from Oman and southern Iran, is the closest relative of a clade consisting of two endemics of the Canary Islands, providing new evidence of the phytogeographical links between Macaronesia and eastern Africa-southern Arabia. Helichrysum gossypinum, the third endemic of the Canary Islands, is the sister species of a monophyletic Mediterranean and Asiatic group, with the four endemics of Madeira sister to all of them. Within the Mediterranean-Asiatic clade, sect. Stoechadina is monophyletic, but sect. Helichrysum and sect. Virginea are not. Once in the Mediterranean region, the genus is hypothesized to have diversified and expanded to the east up to western and central Asia and to have suffered a reduction in woodiness.