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BackgroundYams (Dioscorea spp.) are economically important food for millions of people in the humid and sub-humid tropics. Dioscorea dumetorum (Kunth) is the most nutritious among the eight-yam species, commonly grown and consumed in West and Central Africa. Despite these qualities, the storage ability of D. dumetorum is restricted by severe postharvest hardening of the tubers that can be addressed through concerted breeding efforts. The first step of any breeding program is bound to the study of genetic diversity. In this study, we used the Genotyping-By-Sequencing of Single Nucleotide Polymorphism (GBS-SNP) to investigate the genetic diversity and population structure of 44 accessions of D. dumetorum in Cameroon. Ploidy was inferred using flow cytometry and gbs2ploidy.ResultsWe obtained on average 6371 loci having at least information for 75% accessions. Based on 6457 unlinked SNPs, our results demonstrate that D. dumetorum is structured into four populations. We clearly identified, a western/north-western, a western, and south-western populations, suggesting that altitude and farmers-consumers preference are the decisive factors for differential adaptation and separation of these populations. Bayesian and neighbor-joining clustering detected the highest genetic variability in D. dumetorum accessions from the south-western region. This variation is likely due to larger breeding efforts in the region as shown by gene flow between D. dumetorum accessions from the south-western region inferred by maximum likelihood. Ploidy analysis revealed diploid and triploid levels in D. dumetorum accessions with mostly diploid accessions (77%). Male and female accessions were mostly triploid (75%) and diploid (69%), respectively. The 1C genome size values of D. dumetorum accessions were on average 0.333 ± 0.009 pg and 0.519 ± 0.004 pg for diploids and triploids, respectively.ConclusionsGermplasm characterization, population structure and ploidy are an essential basic information in a breeding program as well as for conservation of intraspecific diversity. Thus, results obtained in this study provide valuable information for the improvement and conservation of D. dumetorum. Moreover, GBS appears as an efficient powerful tool to detect intraspecific variation.Electronic supplementary materialThe online version of this article (10.1186/s12870-018-1593-x) contains supplementary material, which is available to authorized users.

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Climatic fluctuations in the Pleistocene caused glacial expansion-contraction cycles in Eurasia and other parts of the world. Consequences of these cycles, such as population expansion and subsequent subdivision, have been studied in many taxa at intraspecific population level across much of the Northern Hemisphere. However, the consequences for the potential of hybridization and polyploidization are poorly understood. Here, we investigated the phylogeographic structure of two widespread, closely related species, Veronica spicata and Veronica longifolia, across their European distribution ranges. We assessed the extent and the geographic pattern of polyploidization in both species and hybridization between them. We used genome-scale SNP data to clarify phylogenetic relationships and detect possible hybridization/introgression events. In addition, crossing experiments were performed in different combination between V. spicata and V. longifolia individuals of two ploidy levels and of different geographic origins. Finally, we employed ecological niche modeling to infer macroclimatic differences between both species and both ploidy levels. We found a clear genetic structure reflecting the geographical distribution patterns in both species, with V. spicata showing higher genetic differentiation than V. longifolia. We retrieved significant signals of hybridization and introgression in natural populations from the genetic data and corroborated this with crossing experiments. However, there were no clear phylogeographic patterns and unequivocal macroclimatic niche differences between diploid and tetraploid lineages. This favors the hypothesis, that autopolyploidization has happened frequently and in different regions. The crossing experiments produced viable hybrids when the crosses were made between plants of the same ploidy levels but not in the interploidy crosses. The results suggest that hybridization occurs across the overlapping areas of natural distribution ranges of both species, with apparently directional introgression from V. spicata to V. longifolia. Nevertheless, the two species maintain their species-level separation due to their adaptation to different habitats and spatial isolation rather than reproductive isolation.

Hardly any molecular studies have been done on euendoliths of marine coastal environments, especially along the supratidal ranges of carbonate coasts. In our study, we provide a comparative sequence analysis using 454 pyrosequencing of the 16S ribosomal RNA (rRNA) gene combined with extensive microscopy of the endolithic community from rock pools of the Croatian Adria. Molecular diversity indices and richness estimates showed high level of diversity, particularly in high-salinity samples. The most common cyanobacteria belong to the order Pleurocapsales, similar to observations on limestone coasts in other parts of the world. Using single-cell amplification sequences of Hormathonema spp., Hyella caespitosa, and Kyrtuthrix dalmatica was for the first time introduced to the public GenBank.Microscopic investigations did not show qualitative variances in diversity among sites with different salinity but clear differences in prevalent organisms from similar environments suggesting that most of them are adapted to inhabit extreme, marine endolithic habitats and that similar species inhabit geographically separated but ecologically similar environments. This is a remarkable concordance rather seldom seen in molecular community studies in support of the hypothesis that endolithic ecosystems are seeded from a global meta-community.The relative diversity of the community is greater than those described from harsh endolithic habitats of cold and hot deserts. The maximum likelihood phylogenetic tree consisting of 166 operational taxonomic units (OTUs) at 96 % sequence similarity revealed 11 distinct clusters. Three clusters contained only epilithic or endolithic taxa, and five clusters contained mixed epilithic and endolithic taxa. Organisms clustered according to their taxonomic affiliations and not to their preferences to salt concentrations.

Members of Veronica subg. Pseudolysimachium are widely known and cultivated for their large and dense ornamental inflorescences. Their success as cultivated plants stems in part to the cross‐compatibility of members of the subgenus and in part to their wide ecological amplitude ranging from species growing in wetlands to those of semi‐deserts. Due to large morphological variation and the presence of intermediate forms growing in sympatry of their putative parents, hybridization between the species is believed to be frequent. The Russian Altai is a center of diversity for the subgenus and many hybrid taxa have been described from there based on morphology. Here, we test these hybrid hypotheses using dominant SRAP markers. The method relies on primers anchored in open reading frames and amplifying intronic regions, which are scored as fragment length polymorphisms. Using seven primer pairs, we analyzed 63 loci without missing data. Our data support a close relationship of V. × grisea, V. × schmakovii and V. taigischensis with V. longifolia while the influence from the other suggested parents V. incana, V. porphyriana and V. pinnata was weak (at most). Similarly, V. × sessiliflora shows strong genetic similarity with V. porphyriana but only slight influence from V. pinnata. Overall, the methodology worked reliably and provided a large number of variable polymorphisms. The lack of support for the hybrid hypotheses may be due to the relatively low number of loci analysed and/or possible backcrossing with one of the parents.

Summary1. This account presents information on all aspects of the biology of Rosa spinosissima L. (R. pimpinellifolia L.) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history, and conservation. 2. Rosa spinosissima is a small, deciduous shrub forming clonal patches from root suckers. In Britain it is common on stabilized coastal dunes, more or less base-rich heaths, and on open, dry habitats on chalk or limestone inland. It is naturally distributed across temperate Europe and western and central Asia. 3. The small leaves and leaflets, in combination with many straight or slightly curved bristles and prickles, and the black hips, make R. spinosissima easily recognizable in Britain. It normally does not exceed 10-40 cm but cultivars often grow taller. 4. The seeds are dispersed by birds and other animals, particularly as the hips are a favoured diet of birds, because of the high vitamin and anthocyanin content. Vegetative spread is frequent through the root suckers. 5. Cultivars are commonly planted for amenity and in gardens. The origin of the cultivars is not known, but genetic exchange of these with natural British populations may lead to introgression with genotypes which are not locally adapted. The invasive Rosa rugosa may be a threat in some coastal habitats as this species is displacing R. spinosissima on the German North Sea coast.

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