48 research outputs found

    How do leaf carbon and nitrogen contents of oak hosts affect the heterotrophic level of Loranthus europaeus? Insights from stable isotope ecophysiology assays

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    Loranthus europaeus is one of the major plant parasites threatening the fragile ecosystems of oak forests in westernIran. The mistletoe is a hemi-parasite plant which grows on forest species, especially oaks. Carbon isotopecomposition (δ13C) has been central to understand the behaviour of mistletoes in the field. This study investigatedC and N isotope compositions in leaves of L. europaeus and of its host oaks (Quercus libani, Q. infectoria andQ. brantii) in western Iran. The goal was to assess the degree of heterotrophy, and to estimate the carbon partitionbetween host and mistletoe and possible consequences of this phenomenon for the ecology of these hemiparasites.Leaf samples from mistletoe and host oaks were collected in the Mirabad forests of Sardasht, Iran.Ten adult trees of each oak species, with the hemiparasite species, were sampled for determination of leaf dryweight and area, concentration in carbon and nitrogen, and contents of stable carbon and nitrogen isotopes. In allthree species, we found that the levels of δ13C of the host, were higher than those of the mistletoes. Quercusinfectoria, with the highest leaf mass per area and the highest carbon and nitrogen contents on a mass basis, wasthe oak species with the highest degree of mistletoe heterotrophy, which was negatively related with the hostmistletoeδ13C difference. Our results also showed that host and mistletoe leaf masses per area can be indicatorsof the heterotrophic degree of the mistletoe and an easy alternative to the determination of δ13C. In conclusion, itseems that the difference in δ13C between host and mistletoe is reduced when the host leaf mass per area, Cmassand Nmass increase. This condition relates to an increased heterotrophic degree of mistletoe.info:eu-repo/semantics/publishedVersio

    Environmental niche divergence among three dune shrub sister species with parapatric distributions

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    Background and Aims The geographical distributions of species are constrained by their ecological requirements. The aim of this work was to analyse the effects of environmental conditions, historical events and biogeographical constraints on the diversification of the three species of the western Mediterranean shrub genus Stauracanthus, which have a parapatric distribution in the Iberian Peninsula. Methods Ecological niche factor analysis and generalized linear models were used to measure the response of all Stauracanthus species to the environmental gradients and map their potential distributions in the Iberian Peninsula. The bioclimatic niche overlap between the three species was determined by using Schoener's index. The genetic differentiation of the Iberian and northern African populations of Stauracanthus species was characterized with GenalEx. The effects on genetic distances of the most important environmental drivers were assessed through Mantel tests and non-metric multidimensional scaling. Key Results The three Stauracanthus species show remarkably similar responses to climatic conditions. This supports the idea that all members of this recently diversified clade retain common adaptations to climate and consequently high levels of climatic niche overlap. This contrasts with the diverse edaphic requirements of Stauracanthus species. The populations of the S. genistoides-spectabilis clade grow on Miocene and Pliocene fine-textured sedimentary soils, whereas S. boivinii, the more genetically distant species, occurs on older and more coarse-textured sedimentary substrates. These patterns of diversification are largely consistent with a stochastic process of geographical range expansion and fragmentation coupled with niche evolution in the context of spatially complex environmental fluctuations. Conclusions: The combined analysis of the distribution, realized environmental niche and phylogeographical relationships of parapatric species proposed in this work allows integration of the biogeographical, ecological and evolutionary processes driving the evolution of species adaptations and how they determine their current geographical ranges.FCT [UID/Multi/04326/2013, SFRH/BD/65659/2009, SFRH/BPD/85040/2012]; Portuguese FCT project COMDUNES [EXPL/BIA-BIC/2311/2013]; FCT BI grant by project COMDUNES; Atraccion de Talento Investigador Programme (Gobierno de Extremadura) [TA13032]info:eu-repo/semantics/publishedVersio

    Can we use niche models of indicator species to predict the distribution of endangered communities?

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    European-wide conservation policies are based on the identification of priority habitats. However, research on conservation biogeography often relies on the results and projections of species distribution models to assess species' vulnerability to global change. We assess whether the distribution and structure of threatened communities can be predicted by the suitability of the environmental conditions for their indicator species. We present some preliminary results elucidating if using species distribution models of indicator species at a regional scale is a valid approach to predict these endangered communities. Dune plant assemblages, affected by severe conditions, are excellent models for studying possible interactions among their integrating species and the environment. We use data from an extensive survey of xerophytic inland sand dune scrub communities from Portugal, one of the most threatened habitat types of Europe. We identify indicator shrub species of different types of communities, model their geographical response to the environment, and evaluate whether the output of these niche models are able to predict the distribution of each type of community in a different region

    The contribution of small shrubby patches to the functional diversity of wood-pastures

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    Wood-pastures are grazed systems resulting from a long-term use of natural woodlands by humans. These social-ecological systems, covering vast areas of Europe and other temperate regions, have both high biodiversity and economic values, so many are classified as High Nature Value Farmlands. However, in some regions a loss of spatial heterogeneity threatens this natural value. We investigated the potential contribution of tiny shrubby patches to increase spatial heterogeneity and functional diversity in wood-pasture landscapes. Specifically, we compared functional composition (Community Weighted Means) and functional diversity (Functional Dispersion and Functional Evenness) of assemblages of plants, beetles and lichens in those patches (252-3000 m(2)) and in the wood-pasture matrix. We found that shrubby patches and matrix harbour species assemblages with very distinct functional compositions in all studied taxonomic groups. Evergreen, woody, broad-leafed and fleshy-fruited are better represented in the patches. In beetles, the main differences were a greater prevalence of small-sized and fungivore species in the patches. Shrubby patches also mostly harboured lichens with fruticose- and foliose-broad growth forms, a greater humidity preference, and lower eutrophication tolerance. Moreover, the two indexes used to quantify functional diversity (Functional Dispersion and Functional Evenness) show that, overall, diversity is greater in patches than in the matrix; in patches Functional Dispersion is statistically higher for plants, and Evenness is statistically higher for beetles and lichen. These differences are all consistent with the very distinct ecological conditions in the matrix and patches. The greater overall functional diversity of shrubby patches, and the major differences in functional composition between patches and matrix, observed for all taxa, indicate that these patches greatly enhance the functional diversity of species assemblages in wood-pasture landscapes. Consequently, preserving and promoting tiny shrubby patches is a potentially valuable low-cost management tool to increase biodiversity and improve ecosystem functioning in wood-pasture landscapes.Peer reviewe

    Prenatal diagnosis of a partial dup (16p) due to a rare recombinant resulting from a paternal intrachromosomal insertion

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    Poster: 10.P7Chromosomal rearrangements involving three break-points are relatively rare, about 1/5,000 live births. When a chromosomal segment is moved from one part of a chromosome into another part of the same chromosome, it is considered an intrachromosomal insertion; the orientation of the inserted material in relation to the centromere may remain the same, resulting in a direct insertion, or reversed, resulting in an inverted insertion. A single crossover in the gametogenesis between any of the three breakpoints may result in unbalanced recombinants, leading to phenotypic consequences in the offspring. Partial trisomy 16p is a rare chromosomal imbalance characterized by mental retardation, prenatal and post-natal growth deficiency, facial anomalies, cleft palate, congenital heart defects, and urogenital anomalies. Previous studies have established that the phenotype of this condition is not related to the extension of the duplicated segment and that the region 16p13.1–p13.3 is critical in determining this disorder. We report on a prenatal diagnosis performed at 14 weeks. The fetus presented with an increased fetal nuchal translucency and thus was referred for con- ventional cytogenetic studies. The chromosomal analysis of the amniotic fluid cells revealed a structurally abnormal chromosome 16, with additional material on 16q. The maternal karyotype was normal, but the father carried an intrachromosomal insertion in chromosome 16: a between-arm insertion of a small segment of the short arm into the distal region of the long arm. To characterize the extension of the imbalance in the fetus, chromosome comparative genomic hybridization (cCGH) analysis was performed. Fetus karyotype: 46,XY,rec(16)dup(16p)ins(16) (q24p13.2p13.3)pat.ish cgh dup(16)(p13.2p13.3). The authors emphasize the rarity of this case, explain its possible formation mechanism and compare the fetal phenotype (available after autopsy) with similar cases described in the literatur

    Ecological restoration across the Mediterranean Basin as viewed by practitioners

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    Restoration efforts in the Mediterranean Basin have been changing from a silvicultural to an ecological restoration approach. Yet, to what extent the projects are guided by ecological restoration principles remains largely unknown. To analyse this issue, we built an on-line survey addressed to restoration practitioners. We analysed 36 restoration projects, mostly from drylands (86%). The projects used mainly soil from local sources. The need to comply with legislation was more important as a restoration motive for European Union (EU) than for non-EU countries, while public opinion and health had a greater importance in the latter. Non-EU countries relied more on non-native plant species than EU countries, thus deviating from ecological restoration guidelines. Nursery-grown plants used were mostly of local or regional provenance, whilst seeds were mostly of national provenance. Unexpected restoration results (e.g. inadequate biodiversity) were reported for 50% of the projects and restoration success was never evaluated in 22%. Long term evaluation (> 6 years) was only performed in 31% of cases, and based primarily on plant diversity and cover. The use of non-native species and species of exogenous provenances may: i) entail the loss of local genetic and functional trait diversity, critical to cope with drought, particularly under the predicted climate change scenarios, and ii) lead to unexpected competition with native species and/or negatively impact local biotic interactions. Absent or inappropriate monitoring may prevent the understanding of restoration trajectories, precluding adaptive management strategies, often crucial to create functional ecosystems able to provide ecosystem services. The overview of ecological restoration projects in the Mediterranean Basin revealed high variability among practices and highlighted the need for improved scientific assistance and information exchange, greater use of native species of local provenance, and more long-term monitoring and evaluation, including functional and ecosystem services' indicators, to improve and spread the practice of ecological restoration

    Estimation of the allergenic potential of urban trees and urban parks: Towards the healthy design of urban green spaces of the future

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    The impact of allergens emitted by urban green spaces on health is one of the main disservices of ecosystems. The objective of this work is to establish the potential allergenic value of some tree species in urban environments, so that the allergenicity of green spaces can be estimated through application of the Index of Urban Green Zones Allergenicity (IUGZA). Multiple types of green spaces in Mediterranean cities were selected for the estimation of IUGZ. The results show that some of the ornamental species native to the Mediterranean are among the main causative agents of allergy in the population; in particular, Oleaceae, Cupressaceae, Fagaceae, and Platanus hispanica. Variables of the strongest impact on IUGZA were the bioclimatic characteristics of the territory and design aspects, such as the density of trees and the number of species. We concluded that the methodology to assess the allergenicity associated with urban trees and urban areas presented in this work opens new perspectives in the design and planning of urban green spaces, pointing out the need to consider the potential allergenicity of a species when selecting plant material to be used in cities. Only then can urban green areas be inclusive spaces, in terms of public health.This work has been made possible thanks to members of the Silva MediterraneaWorking Group on Urban and Peri-Urban Forestry (FAO WG7) and COST Action FP1204 Green Infrastructure approach: linking environmental with social aspects in studying and managing urban forests. Nezha Acil thanks the technical sta of ISESCO park for their help during his first visit to the park. Maria Beatrice Andreucci also thanks students Giada Di Sante, Guglielmo Pirri e Daniele Purini for her course in Environmental Technological Design of the Master degree in Landscape Architecture at Sapienza Università di Roma for participation in the tree inventory and Duilio Iamonico for the tree taxonomy classification review. The research by the Slovenian Forestry Institute was financially supported by the Program and Research group P4-0107 “Forest ecology, biology and technology” funded by the Slovenian Research Agency.info:eu-repo/semantics/publishedVersio

    Livro Verde dos Montados

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    O Livro Verde dos Montados apresenta diversos objectivos que se interligam: Em primeiro lugar, o Livro Verde pretende reunir e sistematizar, de uma forma simples e acessível ao público, o conhecimento produzido em Portugal pelos investigadores e técnicos de várias instituições de investigação ou de gestão que estudam o Montado. Assume-se como uma oportunidade de caracterizar o sistema tendo em conta as suas várias dimensões, identificando as principais ameaças à sua preservação assim como os caminhos que podem ajudar à sua sustentabilidade. Não sendo um documento científico, baseia-se no conhecimento científico e pretende constituir a base para uma plataforma de organização, tanto dos investigadores como do conhecimento científico actualmente produzido em Portugal sobre o Montado.Em segundo lugar, o Livro Verde deverá contribuir para um entendimento partilhado do que é o Montado, por parte do público, de técnicos e de especialistas, conduzindo a uma classificação mais clara do que pode ser considerado Montado e de quais os tipos distintos de Montados que podem ser identificados. Em terceiro lugar, o Livro Verde estabelece as bases para uma estratégia coordenada de disponibilização de informação sobre o sistema Montado, visando o seu conhecimento, apreciação e valorização pela sociedade portuguesa no seu conjunto. Deste modo, o Livro Verde poderá constituir um instrumento congregador e inspirador para a realização de acções de sensibilização e informação sobre o Montado. Em quarto lugar, pretende-se que o Livro Verde contribua para um maior reconhecimento e valorização do Montado como sistema, a nível do desenho das políticas nacionais por parte dos vários sectores envolvidos.Finalmente, o Livro Verde constituirá um documento parceiro do Livro Verde das Dehesas, produzido em Espanha em 2010, de forma a reforçar o reconhecimento e a devida valorização destes sistemas silvo-pastoris no desenho das estratégias e políticas relevantes pelas instituições europeias. Em suma, os autores pretendem que o Livro Verde dos Montados se afirme como o primeiro passo para uma efectiva definição e implementação de uma estratégia nacional para os Montados

    Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

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    A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

    Measurements of top-quark pair differential cross-sections in the eμe\mu channel in pppp collisions at s=13\sqrt{s} = 13 TeV using the ATLAS detector

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