Progress in the study of genome size evolution in Asteraceae: analysis of the last update

The Genome Size in Asteraceae database (GSAD, http://www.asteraceaegenomesize.com) has been recently updated, with data from papers published or in press until July 2018. This constitutes the third release of GSAD, currently containing 4350 data entries for 1496 species, which represent a growth of 22.52% in the number of species with available genome size data compared with the previous release, and a growth of 57.72% in terms of entries. Approximately 6% of Asteraceae species are covered in terms of known genome sizes. The number of source papers included in this release (198) means a 48.87% increase with respect to release 2.0. The significant data increase was exploited to study the genome size evolution in the family from a phylogenetic perspective. Our results suggest that the role of chromosome number in genome size diversity within Asteraceae is basically associated to polyploidy, while dysploidy would only cause minor variation in the DNA amount along the family. Among diploid taxa, we found that the evolution of genome size shows a strong phylogenetic signal. However, this trait does not seem to evolve evenly across the phylogeny, but there could be significant scale and clade-dependent patterns. Our analyses indicate that the phylogenetic signal is stronger at low taxonomic levels, with certain tribes standing out as hotspots of autocorrelation between genome size and phylogeny. Finally, we also observe meaningful associations among nuclear DNA content on Asteraceae species and other phenotypical and ecological traits (i.e. plant habit and invasion ability). Overall, this study emphasizes the need to continue generating and analyzing genome size data in order to puzzle out the evolution of this parameter and its many biological correlates

Molecular insights into the diversification of Cheirolophus (Asteraceae) in Macaronesia

Podeu consultar el llibre complet a: http://hdl.handle.net/2445/67430The diversification of Cheirolophus in Macaronesian archipelagos constitutes a paradigmatic example of radiation on oceanic islands. Phylogenetic and molecular dating analyses indicate an extraordinarily fast process, showing one of the highest speciation rates ever found on plants from oceanic islands. Such radiation has been recently studied employing phylogeographic, population genetic and molecular cytogenetic approaches. Here, the main potential patterns and processes involved in the diversification of the genus in the Canary Islands and Madeira are reviewed and discussed as a whole

Genetic structure and seed germination in Portuguese populations of Cheirolophus uliginosus (Asteraceae): Implications for conservation strategies

Cheirolophus uliginosus is a threatened species, endemic to the Atlantic coast of the Iberian Peninsula, where it occupies a few restricted localities. In our study we analysed the patterns of cpDNA haplotypes variation and reproductive success germinability among seven Portuguese populations of varying size. The aim was to examine the reproductive performance of Ch. uliginosus related to genetic structure and population size. The results showed very low within-population variability of cpDNA markers. Our study indicates that the germination rate is significantly reduced in small populations ( 250 individuals) do not show any constraint. In the search for plausible causes explaining the lower germination success in the smallest populations, ecological concerns and genetic isolation must be taken into account. Besides, in large-sized populations of Ch. uliginosus (> 250 plants) a higher incidence of predispersal seed predation was observed, maybe affecting their sexual reproductive response. Finally, smaller populations presenting a reduced reproductive success contain also the most evolutionary distant haplotypes, so their conservation should be a priority

Phylogeography of Dictyota fasciola and Dictyota mediterranea (Dictyotales, Phaeophyceae): unexpected patterns on the Atlantic-Mediterranean marine transition and taxonomic implications

The Atlantic-Mediterranean marine transition is a fascinating biogeographic region, but still very poorly studied from the point of view of seaweed phylogeography. Dictyota fasciola and D. mediterranea (Dictyotales, Phaeophyceae) are two currently recognized sister species that share a large part of their distribution along the Mediterranean Sea and the Atlantic Ocean, representing a unique study model to understand the diversification processes experienced by macroalgae during and after Messinian at this marine region. In this study, we sampled 102 individuals of D. fasciola and D. mediterranea from 32 localities along their distribution range and sequenced the mitochondrial cox1 and the chloroplast rbcL-rbcS DNA regions for all the samples. Our data do not support the occurrence of two sister species but a morphologically variable and highly genetic diverse species or a complex of species. Most of the observed genetic diversity corresponds to the Mediterranean populations, whereas the Atlantic ones are much more homogeneous. The early-diverged lineages inferred from both mtDNA and cpDNA phylogenetic reconstructions were constituted by samples from the Mediterranean Sea. Together, these results suggest that the Mediterranean Sea acted as a refugium for the D. fasciola-D. mediterranea lineage during the geologic and climatic changes occurred on the region since the Miocene, subsequently dispersing to the Atlantic Ocean

The explosive radiation of Cheirolophus (Asteraceae, Cardueae) in Macaronesia

Considered a biodiversity hotspot, the Canary Islands have been the key subjects of numerous evolutionary studies concerning a large variety of organisms. The genus Cheirolophus (Asteraceae) represents one of the largest plant radiations in the Canarian archipelago. In contrast, only a few species occur in the Mediterranean region, the putative ancestral area of the genus. Here, our main aim was to reconstruct the phylogenetic and biogeographic history of Cheirolophus with special focus on explaining the origin of the large Canarian radiation. Results: We found significant incongruence in phylogenetic relationships between nuclear and plastid markers. Each dataset provided resolution at different levels in Cheirolophus: the nuclear markers resolved the backbone of the phylogeny while the plastid data provided better resolution within the Canarian clade. The origin of Cheirolophus was dated in the Mid-Late Miocene, followed by rapid diversification into the three main Mediterranean lineages and the Macaronesian clade. A decrease in diversification rates was inferred at the end of the Miocene, with a new increase in the Late Pliocene concurrent with the onset of the Mediterranean climate. Diversification within the Macaronesian clade started in the Early-Mid Pleistocene, with unusually high speciation rates giving rise to the extant insular diversity. Conclusions: Climate-driven diversification likely explains the early evolutionary history of Cheirolophus in the Mediterranean region. It appears that the exceptionally high diversification rate in the Canarian clade was mainly driven by allopatric speciation (including intra-and interisland diversification). Several intrinsic (e.g. breeding system, polyploid origin, seed dispersal syndrome) and extrinsic (e.g. fragmented landscape, isolated habitats, climatic and geological changes) factors probably contributed to the progressive differentiation of populations resulting in numerous microendemisms. Finally, hybridization events and emerging ecological adaptation may have also reinforced the diversification process

Contribution to the knowledge of genome size evolution in edible blueberries (genus Vaccinium)

BACKGROUND: Vaccinium is one of the largest genera (ca. 500 species) of Ericaceae, well known for its edible and ornamental uses. Although there is certain karyological knowledge, information about genome size (GS) is scarce in the genus. OBJECTIVE: The main goal is providing GS data for several Vaccinium species with prevalence in Europe and Western Asia and analysing global GS variation in the genus, considering available data and phylogenetic context. METHODS: New GS assessments were obtained by flow cytometry and chromosome counts were verified. Phylogenetic analyses (using nuclear ITS, and chloroplastic matK and ndhF) were performed by Bayesian inference and reconstruction of ancestral GS by maximum parsimony. RESULTS: We obtained GS data for five Vaccinium species (13 populations). Three species are reported for the first time. Values (2C) ranged between 1.16-1.47 pg at the diploid (2n = 24) and between 3.13-3.16 pg at the tetraploid (2n = 48) levels. The five species here investigated have been placed and analysed in a reconstructed phylogenetic background (including 68 taxa). CONCLUSIONS: GS values of Vaccinium can be considered "very small". The preliminary reconstruction of ancestral GS would point to a reduction in Vaccinium, although more data is needed to establish global GS evolutionary trend in the genus

Pellaea calomelanos (Pteridaceae) in Catalonia: is it really a very old disjunction?

Pellaeacalomelanos(Pteridaceae) in catalonia: isitreallyaveryolddisjunction? Pellaea calomelanos is a species discovered in Africa and whose distribution area has been expanding more recently to Asia and to a single European locality, including three populations, in Catalonia. Both, the fact of belonging to ferns and presenting this disjoint distribution fostered the idea of a relict species resulting from an extensive distribution in remote times. The 2C-values range from 16.45 pg for the individual of the Reunion Island to 17.40 pg for the population of Boadella (Catalonia). Although a certain variability exists, no statistically significant differences among them have been found. The phylogenetic analysis reveals a well-supported clade grouping all the individuals of the different populations of P. calomelanos but without any kind of internal resolution. The results of this work, based on measures of nuclear DNA amount and also on two regions of chloroplast DNA sequencing, together with the characteristics of its habitat, allow the authors to hypothesize about a recent colonisation of the European continent by this species.Keywords: Bayesian inference; ferns; nuclear DNA amount; phylogenetic analyses; Pteridaceae; 2C-value

Phenolic Compounds Content and Genetic Diversityat Population Level across the Natural Distribution Range of Bearberry (Arctostaphylos uva-ursi, Ericaceae) in the Iberian Peninsula

Bearberry (Arctostaphylos uva-ursi) is a medicinal plant traditionally employed for the treatment of urinary tract infections due to high contents of arbutin (hydroquinone β-D-glucoside), which is now mainly used as a natural skin-whitening agent in cosmetics. Bearberry has also been proposed as a natural antioxidant additive due to the high contents of phenolic compounds in leaves. We studied the variation on phenolic compounds in 42 wild populations of bearberry, aiming to elucidate if intrinsic biological, climatic, and/or geographic factors affect phenolic contents across its natural distribution in the Iberian Peninsula. Bearberry leaves were collected during autumn over a three-year period (2014-2016) in populations across a latitude and altitude gradient. Methanolic extracts showed a wide range of variation in total phenols content, and different phenolic profiles regarding arbutin (levels of this major constituent varied from 87 to 232 mg/g dr wt), but also catechin and myricetin contents, which were affected by geographic and climatic factors. Moderate levels of variation on genome size-assessed by flow cytometry-and on two plastid DNA regions were also detected among populations. Genetic and cytogenetic differentiation of populations was weakly but significantly associated to phytochemical diversity. Elite bearberry genotypes with higher antioxidant capacity were subsequently identified

Key processes for Cheirolophus (Asteraceae) diversification on oceanic islands inferred from AFLP data

The radiation of the genus Cheirolophus (Asteraceae) in Macaronesia constitutes a spectacular case of rapid diversification on oceanic islands. Twenty species - nine of them included in the IUCN Red List of Threatened Species - have been described to date inhabiting the Madeiran and Canarian archipelagos. A previous phylogenetic study revealed that the diversification of Cheirolophus in Macaronesia started less than 2 Ma. As a result of such an explosive speciation process, limited phylogenetic resolution was reported, mainly due to the low variability of the employed molecular markers. In the present study, we used highly polymorphic AFLP markers to i) evaluate species' boundaries, ii) infer their evolutionary relationships and iii) investigate the patterns of genetic diversity in relation to the potential processes likely involved in the radiation of Cheirolophus. One hundred and seventy-two individuals representing all Macaronesian Cheirolophus species were analysed using 249 AFLP loci. Our results suggest that geographic isolation played an important role in this radiation process. This was likely driven by the combination of poor gene flow capacity and a good ability for sporadic long-distance colonisations. In addition, we also found some traces of introgression and incipient ecological adaptation, which could have further enhanced the extraordinary diversification of Cheirolophus in Macaronesia. Last, we hypothesize that current threat categories assigned to Macaronesian Cheirolophus species do not reflect their respective evolutionary relevance, so future evaluations of their conservation status should take into account the results presented here

A phylogenetic road map to antimalarial Artemisia species

Ethnopharmacological relevance The discovery of the antimalarial agent artemisinin is considered one of the most significant success stories of ethnopharmacological research in recent times. The isolation of artemisinin was inspired by the use of Artemisia annua in traditional Chinese medicine (TCM) and was awarded a Nobel Prize in 2015. Antimalarial activity has since been demonstrated for a range of other Artemisia species, suggesting that the genus could provide alternative sources of antimalarial treatments. Given the stunning diversity of the genus (c. 500 species), a prioritisation of taxa to be investigated for their likely antimalarial properties is required. Materials and methods Here we use a phylogenetic approach to explore the potential for identifying species more likely to possess antimalarial properties. Ethnobotanical data from literature reports is recorded for 117 species. Subsequent phylogenetically informed analysis was used to identify lineages in which there is an overrepresentation of species used to treat malarial symptoms, and which could therefore be high priority for further investigation of antimalarial activity. Results We show that these lineages indeed include several species with documented antimalarial activity. To further inform our approach, we use LC-MS/MS analysis to explore artemisinin content in fifteen species from both highlighted and not highlighted lineages. We detected artemisinin in nine species, in eight of them for the first time, doubling the number of Artemisia taxa known to content this molecule. Conclusions Our findings indicate that artemisinin may be widespread across the genus, providing an accessible local resource outside the distribution area of Artemisia annua