Explanation of beta diversity in European alpine grasslands changes with scale

The importance of environmental difference among sites and dispersal limitations of species to the explanation of diversity differs among biological systems and geographical regions. We hypothesized that climate and then dispersal limitation will predominantly explain the similarity of alpine vegetation at increasing distances between pairs of regions at subcontinental extent. We computed the similarity of all pairs of 23 European mountain regions below 50 degrees N after dividing the species lists of each region by calcareous or siliceous substrates. Distance decay in similarity was better fitted by a cubic polynomial than a negative exponential function, and the fit was better on calcareous than on siliceous substrate. Commonality analysis revealed that the proportion of explanation of beta diversity by climatic difference had unimodal patterns on a gradient of increasing distance between regions, while explanation by dispersal limitation had consistently rising patterns on both substrates. On siliceous substrate, dispersal limitation explained more of the variation in beta diversity only at longer distances, but it was predominant at all distances on calcareous substrate. The steeper response to distance at 2600 km may indicate dispersal limitation at different temporal scales, and the uptick in the response to distance at the longest distances may reflect how isolated some regions have been before and since the last glacial maximum

Post-glacial determinants of regional species pools in alpine grasslands

[Aim] Alpine habitats support unique biodiversity confined to high-elevation areas in the current interglacial. Plant diversity in these habitats may respond to area, environment, connectivity and isolation, yet these factors have been rarely evaluated in concert. Here we investigate major determinants of regional species pools in alpine grasslands, and the responses of their constituent species groups.[Location] European mountains below 50° N.[Time period] Between 1928 and 2019.[Major taxa studied] Vascular plants.[Methods] We compiled species pools from alpine grasslands in 23 regions, including 794 alpine species and 2,094 non-alpines. We used species–area relationships to test the influence of the extent of alpine areas on regional richness, and mixed-effects models to compare the effects of 12 spatial and environmental predictors. Variation in species composition was addressed by generalized dissimilarity models and by a coefficient of dispersal direction to assess historical links among regions.[Results] Pool sizes were partially explained by current alpine areas, but the other predictors largely contributed to regional differences. The number of alpine species was influenced by area, calcareous bedrock, topographic heterogeneity and regional isolation, while non-alpines responded better to connectivity and climate. Regional dissimilarity of alpine species was explained by isolation and precipitation, but non-alpines only responded to isolation. Past dispersal routes were correlated with latitude, with alpine species showing stronger connections among regions.[Main conclusions] Besides area effects, edaphic, topographic and spatio-temporal determinants are important to understand the organization of regional species pools in alpine habitats. The number of alpine species is especially linked to refugia and isolation, but their composition is explained by past dispersal and post-glacial environmental filtering, while non-alpines are generally influenced by regional floras. New research on the dynamics of alpine biodiversity should contextualize the determinants of regional species pools and the responses of species with different ecological profiles.The authors thank Daniela Gaspar for support in GIS analyses. B.J.-A. thanks the Marie Curie Clarín-COFUND program of the Principality of Asturias-EU (ACB17-26), the regional grant IDI/2018/000151, and the Spanish Research Agency grant AEI/ 10.13039/501100011033. J.V.R.-D. was supported by the ACA17-02FP7 Marie Curie COFUND-Clarín grant. G.P.M. was funded by US National Science Foundation award 1853665. C.M. was funded by grant no. 19-28491 of the Czech Science Foundation.Peer reviewe

Increased lipodystrophy is associated with increased exposure to highly active antiretroviral therapy in HIV-infected children

Objective: To assess body composition changes in HIV-infected children receiving highly active antiretroviral therapy (HAART). Methods: Thirty-seven HIV-positive children were enrolled. Dual-energy X-ray absorptiometry (DXA) scans were performed in all HIV-infected children at baseline and after an additional 12 months of HAART and in 54 matched (for sex, age, body mass index [BMI], and pubertal stage) healthy controls. Abdominal MRI was performed in 14 of 37 HIV-positive children at baseline and in 28 of 37 HIV-positive children after additional 12 months of HAART. Results: During the study period, mean HAART exposure increased from 39.3 to 50.9 months and the number of HIV-infected children with clinical lipodystrophy (LD) increased from 6 to 8, whereas mean BMI, CD4 percentage, and percentage of HIV-infected children with HIV RNA <50 copies/mL did not change. DXA scans showed an increase in lean mass, peripheral fat loss, and central fat accumulation in all HIV-infected children. As compared with controls, 70% and 84% of HIV-infected children showed DXA-detectable LD at baseline and at 12 months of follow-up, respectively. Mixed LD and central fat accumulation were the most common LD phenotype. At baseline and at 12 months of follow-up, intra-abdominal adipose tissue (IAT) was greater than in controls in 33% and 35% of HIV-infected children, and it was greater in those with LD than in those without. Peripheral fat loss and IAT content were associated with duration of HAART and were independent of immunologic stage of disease and immunologic response. Conclusions: Changes in body composition related to LD in HAART-treated children are frequent, precocious, and progressive. Duration of HAART negatively influences visceral adiposity and peripheral fat loss

Towards a checklist of floras of Mediterranean islands

International audienceAccess to large datasets is fundamental for studying biogeographical and macroecological patterns, and for planning conservation actions. The Mediterranean basin hosts 2212 islands larger than 10,000 m2, with endemic species and peculiar plant communities of great conservation value. Despite the intense study of their flora, a comprehensive and accessible catalog is still lacking. With this study we tested the coverage of 3 databases concerning plant data on Mediterranean islands, to start building up a first open floristic checklist at the basin scale. We retrieved vascular plant occurrences from EVA, GIFT, and GBIF; we investigated the overlap of data among the three harmonized sources and looked for potential data gaps. We found that GBIF has the largest coverage (633 islands), but often limited to few occurrences on smaller islands; GIFT checklists, instead, are generally more complete than EVA and GBIF ones. We noticed that referring to GBIF data only biases the definition of the island species pool composition, while the combined use of the three sources significantly improves it. This contribution is a step towards a floristic catalog of Mediterranean islands and can represent a useful tool for defining conservation plans for island biodiversity at the basin scale

DNA Markers for Food Products Authentication

Media constantly refer of unscrupulous producers that adulterate, alter or replace premium products in food chains with the goal to maximize illegally profits. Food traceability is a central issue for the identification of improper labeling of processed food and feed and there are rules aimed to protect consumers and producers against fraudulent substitution of quality products in food chain, but the tools available are not always appropriate. DNA-based markers proved very effective for fresh and processed food molecular authentication. In this review, we illustrate potential and limits of different DNA markers focusing on low, medium and high-throughput markers, in order to monitor the genetic identity of food components in meat, fish and plants net-chains