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Comparative genomics of bdelloid rotifers: insights from desiccating and nondesiccating species
No full textBdelloid rotifers are a class of microscopic invertebrates that have existed for millions of years apparently without sex or meiosis. They inhabit a variety of temporary and permanent freshwater habitats globally, and many species are remarkably tolerant of desiccation. Bdelloids offer an opportunity to better understand the evolution of sex and recombination, but previous work has emphasised desiccation as the cause of several unusual genomic features in this group. Here, we present high-quality whole-genome sequences of 3 bdelloid species: Rotaria macrura and R. magnacalcarata, which are both desiccation intolerant, and Adineta ricciae, which is desiccation tolerant. In combination with the published assembly of A. vaga, which is also desiccation tolerant, we apply a comparative genomics approach to evaluate the potential effects of desiccation tolerance and asexuality on genome evolution in bdelloids. We find that ancestral tetraploidy is conserved among all 4 bdelloid species, but homologous divergence in obligately aquatic Rotaria genomes is unexpectedly low. This finding is contrary to current models regarding the role of desiccation in shaping bdelloid genomes. In addition, we find that homologous regions in A. ricciae are largely collinear and do not form palindromic repeats as observed in the published A. vaga assembly. Consequently, several features interpreted as genomic evidence for long-term ameiotic evolution are not general to all bdelloid species, even within the same genus. Finally, we substantiate previous findings of high levels of horizontally transferred nonmetazoan genes in both desiccating and nondesiccating bdelloid species and show that this unusual feature is not shared by other animal phyla, even those with desiccation-tolerant representatives. These comparisons call into question the proposed role of desiccation in mediating horizontal genetic transfer
Remote sensing based comprehensive monitoring of land cover change in protected areas
No full textLand cover changes - due to climate or land use change ? are a common challenge for the management of protected areas. Over the last decades, large parts of the European Alps have experienced forest expansion and shrub encroachment as a consequence of land abandonment. Also the Gran Paradiso National Park experiences such vegetation successional processes, which might be a threat to some local habitats and species. Remote sensing is in general a unique tool to map rates and spatial pattern of land cover change even for remote areas that are hard to monitor. In this study, hence, we aim to explore the potential for identifying hotspots of land cover change over the entire area of park based on remote sensing data. Land cover changes for the entire Gran Paradiso National Park are explored from 1984 to 2016 based on all available Landsat TM, ETM+ and OLI images at a spatial resolution of 30 by 30 m. To map forest expansion and shrub encroachment we combined bi-temporal and time-series change detection methods and validated our results using orthophotos
Measuring ?-diversity by remote sensing: A challenge for biodiversity monitoring
No full text1. Biodiversity includes multiscalar and multitemporal structures and processes, with different levels of functional organization, from genetic to ecosystemic levels. One of the mostly used methods to infer biodiversity is based on taxonomic approaches and community ecology theories. However, gathering extensive data in the field is difficult due to logistic problems, especially when aiming at modelling biodiversity changes in space and time, which assumes statistically sound sampling schemes. In this context, airborne or satellite remote sensing allows information to be gathered over wide areas in a reasonable time. 2. Most of the biodiversity maps obtained from remote sensing have been based on the inference of species richness by regression analysis. On the contrary, estimating compositional turnover (?-diversity) might add crucial information related to relative abundance of different species instead of just richness. Presently, few studies have addressed the measurement of species compositional turnover from space. 3. Extending on previous work, in this manuscript, we propose novel techniques to measure ?-diversity from airborne or satellite remote sensing, mainly based on: (1) multivariate statistical analysis, (2) the spectral species concept, (3) self-organizing feature maps, (4) multidimensional distance matrices, and the (5) Rao\u27s Q diversity. Each of these measures addresses one or several issues related to turnover measurement. This manuscript is the first methodological example encompassing (and enhancing) most of the available methods for estimating ?-diversity from remotely sensed imagery and potentially relating them to species diversity in the field
Explaining Leaf Nitrogen Distribution in a Semi-Arid Environment Predicted on Sentinel-2 Imagery Using a Field Spectroscopy Derived Model
No full textLeaf nitrogen concentration (leaf N, %) is an essential component for understanding biogeochemical cycling. Leaf N is a good indicator of grass or forage quality, which is important for understanding the movements and feeding patterns of herbivores. Leaf N can be used as input for rangeland carrying capacity and stocking rate models. The estimation of leaf N has been successful using hyperspectral and commercial high spatial resolution satellite data such as WorldView-2 and RapidEye. Empirical methods have been used successfully to estimate leaf N, on the basis that it correlates with leaf chlorophyll. As such, leaf N was estimated using red edge based indices. The new Sentinel-2 sensor has two red edge bands, is freely available, and could further improve the estimation of leaf N at a regional scale. The objective of this study is to develop red edge based Sentinel-2 models derived from an analytical spectral device (ASD) spectrometer to map and monitor leaf N using Sentinel-2 images. Field work for leaf N and ASD data were collected in 2014 (December) in and around Kruger National Park, South Africa. ASD data were resampled to the Sentinel-2 spectral configuration using the spectral response function. The Sentinel-2 data for various dates were acquired from the European Space Agency (ESA) portal. The Sentinel-2 atmospheric correction (Sen2Cor) process was implemented. Simple empirical regression was used to estimate leaf N. High leaf N prediction accuracy was achieved at the ASD level and the best model was inverted on Sentinel-2 images to explain leaf N distribution at a regional scale over time. The spatial distribution of leaf N is influenced by the underlying geological substrate, fire frequency and other environmental variables. This study is a demonstration of how ASD data can be used to calibrate Sentinel-2 for leaf N estimation and mapping
Analysis of coastal areas using SAR images: case study of the Dutch Wadden Sea region
No full textThe increased availability of civil synthetic aperture radar (SAR) satellite images with different resolution allows us to compare the imaging capabilities of these instruments, to assess the quality of the available data and to investigate different areas (e.g., the Wadden Sea region). In our investigation, we propose to explore the content of TerraSAR-X and Sentinel-1A satellite images via a data mining approach in which the main steps are patch tiling, feature extraction, classification, semantic annotation and visual-statistical analytics. Once all the extracted categories are mapped and quantified, then the next step is to interpret them from an environmental point of view. The objective of our study is the application of semi-automated SAR image interpretation. Its novelty is the automated multiclass categorization of coastal areas. We found out that the north-west of the Netherlands can be interpreted routinely as land surfaces by our satellite image analyses, while for the Wadden Sea, we can discriminate the different water levels and their impact on the visibility of the tidal flats. This necessitates a selection of time series data spanning a full tidal cycle
The management of wild reindeer (Rangifer tarandus) in Hardangervidda National Park, Norway
No full textHardangervidda is the largest mountain plateau in northern Europe, and is home to the largest wild reindeer (Rangifer tarandus) population on the european continent. Wild reindeer are often considered keystone species of the circumpolar region, because they influence ecosystem processes such as nutrient cycling and primary production (e.g. OLOFSSON et al, 2004). The reindeer population on the Hardangervidda plateau is important for its ecological value, and for its economical and recreational value for hunters, hikers and landowners (BJERKETVEDT et al, 2014). A loss of this herd would have a negative impact not only for the ecosystem, but also for the people that depend on it for their livelihood. The protection of the largest population of wild reindeer in Europe was one of the main reasons to designate Hardangervidda National Park. Hardangervidda\u27s wild reindeer population has had frequent and extreme fluctuations in harvest numbers over the last six decades because data on herd size is unreliable, there is a lack of data on recruitment and other life stage characteristics, and because there is a high variation in hunting success (BJERKETVEDT et al, 2014; STRAND et al, 2004). Thus, more reliable population data is sorely needed
How can global conventions for biodiversity and ecosystem services guide local conservation actions?
No full textWith global science-policy conventions for biodiversity and ecosystem services in place, much effort goes into monitoring and reporting on the progress toward policy targets. As conservation actions happen locally, can such global monitoring and reporting efforts effectively guide conservation actions at subnational level? In this paper we explore three different perspectives: policy reporting for policy implementation; scienti?c knowledge for empowerment and actions; and from past trends to in?uencing the future. Using these three perspectives, we identify ways forward for both decision makers and scientists on how to engage, inform and empower a larger diversity of actors who make decisions on the future of biodiversity and ecosystem services at multiple scales
Elevation dependent warming in global climate model simulations at high spatial resolution.
No full textThe enhancement of warming rates with elevation, so-called elevation-dependent warming (EDW), is one of the regional, still not completely understood, expressions of global warming. Sentinels of climate and environmental changes, mountains have experienced more rapid and intense warming trends in the recent decades, leading to serious impacts on mountain ecosystems and downstream. In this paper we use a state-of-the-art Global Climate Model (EC-Earth) to investigate the impact of model spatial resolution on the representation of this phenomenon and to highlight possible differences in EDW and its causes in different mountain regions of the Northern Hemisphere. To this end we use EC-Earth climate simulations at five different spatial resolutions, from ? 125 to ? 16 km, to explore the existence and the driving mechanisms of EDW in the Colorado Rocky Mountains, the Greater Alpine Region and the Tibetan Plateau-Himalayas. Our results show that the more frequent EDW drivers in all regions and seasons are the changes in albedo and in downward thermal radiation and this is reflected in both daytime and nighttime warming. In the Tibetan Plateau-Himalayas and in the Greater Alpine Region, an additional driver is the change in specific humidity. We also find that, while generally the model shows no clear resolution dependence in its ability to simulate the existence of EDW in the different regions, specific EDW characteristics such as its intensity and the relative role of different driving mechanisms may be different in simulations performed at different spatial resolutions. Moreover, we find that the role of internal climate variability can be significant in modulating the EDW signal, as suggested by the spread found in the multi-member ensemble of the EC-Earth experiments which we use
Skilful forecasting of global fire activity using seasonal climate predictions
No full textSocietal exposure to large fires has been increasing in recent years. Estimating the expected fire activity a few months in advance would allow reducing environmental and socio-economic impacts through short-term adaptation and response to climate variability and change. However, seasonal prediction of climate-driven fires is still in its infancy. Here, we discuss a strategy for seasonally forecasting burned area anomalies linking seasonal climate predictions with parsimonious empirical climate-fire models using the standardized precipitation index as the climate predictor for burned area. Assuming near-perfect climate predictions, we obtained skilful predictions of fire activity over a substantial portion of the global burnable area (~60%). Using currently available operational seasonal climate predictions, the skill of fire seasonal forecasts remains high and significant in a large fraction of the burnable area (~40%). These findings reveal an untapped and useful burned area predictive ability using seasonal climate forecasts, which can play a crucial role in fire management strategies and minimise the impact of adverse climate conditions
Problemi e prospettive dell\u27uso di analisi di isotopi stabili di carbonio e azoto per lo studio di reti trofiche lacustri
No full textNot availableQuando, dieci anni or sono, la Commissione Internazionale per la Protezione delle Acque Italo-Svizzere (CIPAIS) richiese all\u27Istituto per lo Studio degli Ecosistemi di presentare progetti in ambito limnologico innovativi che servissero ad arricchire le conoscenze derivanti dal monitoraggio del lago Maggiore e del suo bacino imbrifero, l\u27occasione fu propizia per avviare indagini che servissero ad una caratterizzazione della rete pelagica lacustre nelle sue diverse componenti, individuando i rapporti trofici e la loro evoluzione nel tempo, in relazione al variare di parametri abiotici e biotici. Studi relativi alla caratterizzazione di rapporti biotici, includendo dinamiche di predazione e competizione all\u27interno dello zooplancton, dipendenza dalla base alimentare fitoplanctonica e dalla pressione predatoria da parte della fauna ittica, erano stati condotti in passato con metodi di analisi statistica, basati sull\u27utilizzo di dati derivanti dall\u27analisi della dinamica delle popolazioni zooplanctoniche. La consapevolezza dell\u27importanza delle conoscenze derivanti da questi primi studi, unita all\u27interesse personale per attivit? che potessero coniugare esperienze di laboratorio, di analisi elementari (cfr. Manca & Tognota 1993; Manca et al. 1994, 1995, 1997) con quelle microscopiche alla base della caratterizzazione del popolamento zooplanctonico del lago, sono stati gli elementi che hanno portato alla formulazione del progetto d\u27indagine della rete trofica pelagica del lago Maggiore anche attraverso l\u27uso di analisi di isotopi stabili di carbonio e azoto. La passione e l\u27interesse per approcci molecolari volti allo studio delle interazioni trofiche nasceva anche, proprio sul caso di studio "lago Maggiore", dal desiderio di comprendere le ragioni del forte declino di Daphnia, osservato nel periodo 1989-1996, per il quale non poteva essere esclusa l\u27ipotesi di una forte limitazione dalla base alimentare. Su questo tema, la compianta studiosa Annie Duncan aveva lavorato, con la messa a punto di un metodo basato su analisi elementari di Daphnia e del loro variare stagionale in relazione alle risorse alimentari (Duncan 1985). L\u27utilizzo di questo metodo permetteva di arricchire le indagini usuali, improntate alla caratterizzazione della densit? di popolazione del popolamento zooplanctonico, nelle sue diverse entit? tassonomiche e nei diversi stadi di sviluppo, con quelle attivit? di laboratorio che mi avevano vista per tanti anni lavorare al fianco di Riccardo de Bernardi e, nello specifico delle analisi elementari, con Gianluigi Giussani. L\u27utilizzo dell\u27analisi degli isotopi stabili di C ed N era da me gi? stato impiegato per un lago alpino sul quale lavoravo da tempo, con l\u27intento di caratterizzarne la rete trofica planctonica, anche in relazione al dibattito sulla dinamica del segnale isotopico dell\u27azoto in laghi privi di pesci (Cattaneo et al. 2004). Furono queste le basi conoscitive dalle quali scatur? il progetto d\u27indagine sul lago Maggiore, andatosi arricchendo nell\u27arco di dieci anni anche con aspetti pi? propriamente legati al flusso di inquinanti persistenti e alla stima della biomagnificazione, dando in tal modo un fondamentale contributo alle indagini sulle sostanze inquinanti ed al ruolo cruciale svolto dallo zooplancton in questo contesto, indagini promosse e finanziate dalla sottocommissione ad hoc istituita in seno alla CIPAIS a seguito della scoperta dell\u27inquinamento da DDT del lago e delle comunit? in esso insediate. Con questo progetto la modernit? degli studi su base molecolare si coniugava con la tradizione di un approccio ecosistemico allo studio dei laghi, connaturata con l\u27Istituto ed espressa nella sua mission, per la quale fondamentale ? stato il poter contare su un gruppo di lavoro multidisciplinare in grado di contribuire, con le specifiche competenze, alle diverse e complesse fasi delle attivit?