Polyploidy is common in the genus Salix. However, little is known about the origin, parentage and genomic composition of polyploid species because of a lack of suitable molecular markers and analysis tools. We established a phylogenomic framework including species of all described sections of Eurasian shrub willows. We analyzed the genomic composition of seven polyploid willow species in comparison to putative diploid parental species to draw conclusions on their origin and the effects of backcrossing and post-origin evolution. We applied recently developed programs like SNAPP, HyDe, and SNiPloid to establish a bioinformatic pipeline for unravelling the complexity of polyploid genomes. RAD sequencing revealed 23,393 loci and 320,010 high quality SNPs for the analysis of relationships of 35 species of Eurasian shrub willows (Salix subg. Chamaetia/ Vetrix). Polyploid willow species appear to be predominantly of allopolyploid origin. More ancient allopolyploidization events were observed for two hexaploid and one octoploid species, while our data suggested a more recent allopolyploid origin for the included tetraploids and identified putative parental taxa. SNiPloid analyses disentangled the different genomic signatures resulting from hybrid origin, backcrossing, and secondary post-origin evolution in the polyploid species. Our RAD sequencing data demonstrate that willow genomes are shaped by ancient and recent reticulate evolution, polyploidization, and post-origin divergence of species.

BackgroundHybridization of species with porous genomes can eventually lead to introgression via repeated backcrossing. The potential for introgression between species is reflected by the extent of segregation distortion in later generation hybrids. Here we studied a population of hybrids between Salix purpurea and S. helvetica that has emerged within the last 30 years on a glacier forefield in the European Alps due to secondary contact of the parental species. We used 5758 biallelic SNPs produced by RAD sequencing with the aim to ascertain the predominance of backcrosses (F1 hybrid x parent) or F2 hybrids (F1 hybrid x F1 hybrid) among hybrid offspring. Further, the SNPs were used to study segregation distortion in the second hybrid generation.ResultsThe analyses in structure and NewHybrids revealed that the population consisted of parents and F1 hybrids, whereas hybrid offspring consisted mainly of backcrosses to either parental species, but also some F2 hybrids. Although there was a clear genetic differentiation between S. purpurea and S. helvetica (FST = 0.24), there was no significant segregation distortion in the backcrosses or the F2 hybrids. Plant height of the backcrosses resembled the respective parental species, whereas F2 hybrids were more similar to the subalpine S. helvetica.ConclusionsThe co-occurrence of the parental species and the hybrids on the glacier forefield, the high frequency of backcrossing, and the low resistance to gene flow via backcrossing make a scenario of introgression in this young hybrid population highly likely, potentially leading to the transfer of adaptive traits. We further suggest that this willow hybrid population may serve as a model for the evolutionary processes initiated by recent global warming.Electronic supplementary materialThe online version of this article (10.1186/s12870-018-1552-6) contains supplementary material, which is available to authorized users.

No abstract

The use of mobile health technologies (mHealth) to ameliorate HIV care has considerably risen in low-and middle-income countries (LMICs) since 2010. Yet, the discrepancies in the results of accompanying studies warrant an updated and systematic consolidation of all available evidence. We report a systematic review of studies testing whether text/image messages, interactive voice response reminders, or calls promote adherence and retention to antiretroviral therapy (ART) in LMICs. We systematically compiled studies published in English until June 2018 from PubMed/Medline, Web of Science, WHO database, ProQuest Dissertations and Theses, and manual search. We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2009 and used frequency analysis to assess reported findings. In total, we compiled 35 published articles: 27 completed studies and 8 protocols. Among the main 27 studies, 17 examine adherence, 5 retention, and 5 both measures. Results indicate that 56% report positive and statistically significantly impacts of mHealth on primary outcomes, the remaining 44% report insignificant results. While 41% of studies found a positive and significant effect for adherence, only 12% improved retention. The evidence shows ambiguous results (with high variability) about the effectiveness of mobile phone-assisted mHealth interventions to boost adherence and retention to ART. The literature also points to short follow-up periods, small samples, and limited geographical coverage. Hence, future research should focus on evaluating longer interventions with more patients spread across wider areas to address whether mHealth can be effectively used in LMICs.

Aim To reconstruct the spatio‐temporal evolution of Fosterella (Bromeliaceae), a genus characterized by a high degree of endemism in the Central Andes, and to account for contemporary patterns of diversity and distribution within the genus. Location Fosterella has its centre of diversity in the Central Andes (24 species), where it occurs in two major biomes: the Yungas and seasonally dry tropical forests (SDTF). The genus displays three major disjunctions: Amazonia (one species), Central America (one species), and the Brazilian Shield (five species). Methods Phylogenetic relationships within Fosterella were inferred based on six plastid DNA regions. Parsimony and likelihood methods, a Bayesian relaxed molecular clock, ancestral area reconstructions, and diversification rate analyses were used to infer the spatio‐temporal evolution of Fosterella. Results The origin of extant lineages of Fosterella was placed in the late Miocene (c. 9.6 Ma) during the last rapid Andean uplift. SDTF and azonal lowland sites were inferred as the most likely ancestral habitats. The Yungas were colonized several times independently from c. 4.7 Ma onwards. Only one clade diversified in the Yungas, indicative of an ecological shift to moister and cooler conditions. Two recent long‐distance dispersals to Central America and to Amazonia were inferred. Diversification rates within Fosterella were found to be constant through time and comparatively low (0.4 species Myr−1). Main conclusions Allopatric speciation is the main mode of diversification in Fosterella. The isolated distribution of suitable habitats fostered the evolution of a high degree of endemism. The low speciation rates in Fosterella contrast with high diversification rates of Andean high‐elevation taxa but are similar to other Andean low‐ to mid‐elevation taxa. The last rapid Andean uplift did not leave a detectable signature in the diversification rates of Fosterella.

The Hengduan Mountains (HDM) in China are an important hotspot of plant diversity and endemism, and are considered to be a secondary diversification center for the woody plant genus Salix L. (Salicaceae). Here we aimed to reconstruct the spatiotemporal evolution of the Salix Chamaetia‐Vetrix clade in the HDM and to test for the occurrence of a local radiation. We inferred phylogenetic relationships based on more than 34 000 restriction‐site associated DNA loci from 27 species. Phylogenetic analyses recovered a well‐resolved tree topology with two major clades, the Eurasian clade and the HDM clade, with a divergence time of ca. 23.9 Ma. Species in the HDM clade originated in the northern part of the range and adjacent areas, and then dispersed into the southern HDM, westwards to the Himalayas and eastwards to the Qinling Mountains. Niche modelling analyses reveal that range contractions occurred in the northern areas during the last glacial maximum, while southward expansions resulted in range overlaps. Reconstructions of character evolution related to plant height, inflorescence, and flower morphology suggest that adaptations to altitudinal distribution contributed to the diversification of the HDM willows. Our data support the occurrence of a radiation in the HDM within the Salix Chamaetia‐Vetrix clade. Dispersal within the mountain system, and to adjacent regions, in addition to survival in glacial refugia shaped the biogeographical history of the clade, while adaptations of the HDM willows along an altitudinal gradient could be important ecological factors explaining the high species diversity of Salix in this area.

The Institute of Social Studies is Europe's longest-established centre of higher education and research in development studies. On 1 July 2009, it became a University Institute of the Erasmus University Rotterdam (EUR). Postgraduate teaching programmes range from six-week diploma courses to the PhD programme. Research at ISS is fundamental in the sense of laying a scientific basis for the formulation of appropriate development policies. The academic work of ISS is disseminated in the form of books, journal articles, teaching texts, monographs and working papers. The Working Paper series provides a forum for work in progress which seeks to elicit comments and generate discussion. The series includes academic research by staff, PhD participants and visiting fellows, and award-winning research papers by graduate students.

According to recent taxonomic treatments, Bromeliaceae subfamily Pitcairnioideae comprise the genera Deuterocohnia, Dyckia, Encholirium, Fosterella and Pitcairnia. We present a dated molecular phylogenetic analysis of a comprehensive taxon set to enable inferences of evolution in the subfamily. Phylogenetic relationships in Pitcairnioideae were reconstructed based on three plastid loci (rpl32‐trnL, rps16‐trnK, 5′ end of matK) and the nuclear single‐copy gene PHYC exon 1, using maximum parsimony, maximum likelihood and Bayesian inference. The plastid phylogenetic analysis supports the monophyly of the subfamily, whereas the nuclear DNA data suggest a nested position of Puyoideae in Pitcairnioideae. Fosterella and Dyckia (including Encholirium) are monophyletic in both analyses, whereas Deuterocohnia is paraphyletic and Pitcairnia remains unresolved in the plastid tree. A Bayesian relaxed clock model applied to the plastid data indicates a diversification of Fosterella and Pitcairnia at c. 6–8 Mya, whereas Deuterocohnia and Dyckia might have diversified at about 2–4 Mya. Our data support the concept that Pitcairnioideae originated in the Andes, followed by numerous dispersal events to South and Central America. Plastid capture events might explain the contrasting topologies of plastid and nuclear trees in Deuterocohnia, whereas the position of Puya needs to be re‐evaluated with additional nuclear markers.