Mountains are the water towers of the world, supplying a substantial part of both natural and anthropogenic water demands
. They are highly sensitive and prone to climate change
, yet their ...importance and vulnerability have not been quantified at the global scale. Here we present a global water tower index (WTI), which ranks all water towers in terms of their water-supplying role and the downstream dependence of ecosystems and society. For each water tower, we assess its vulnerability related to water stress, governance, hydropolitical tension and future climatic and socio-economic changes. We conclude that the most important (highest WTI) water towers are also among the most vulnerable, and that climatic and socio-economic changes will affect them profoundly. This could negatively impact 1.9 billion people living in (0.3 billion) or directly downstream of (1.6 billion) mountainous areas. Immediate action is required to safeguard the future of the world's most important and vulnerable water towers.
Present‐day genetic introgression from domestic pigs into European wild boar has been suggested in various studies. However, no hybrids have been identified beyond doubt mainly because available ...methods were unable to quantify the extent of introgression and rule out natural processes. Genetic introgression from domestic pigs may have far‐reaching ecological consequences by altering traits like the reproduction rate or immunology of wild boar. In this study, we demonstrate a novel approach to investigate genetic introgression in a Northwest (NW) European wild boar data set using a genome‐wide single nucleotide polymorphism (SNP) assay developed for domestic pigs. We quantified the extent of introgression using allele frequency spectrum analysis, in silico hybridization simulations and genome distribution patterns of introgressed SNPs. Levels of recent introgression in the study area were expected to be low, as pig farming practices are prevailingly intensive and indoors. However, evidence was found for geographically widespread presence of domestic pig SNPs in 10% of analysed wild boar. This was supported by the identification of two different pig mitochondrial DNA haplotypes in three of the identified hybrid wild boar, suggesting that introgression had occurred from multiple sources (pig breeds). In silico hybridization simulations showed that the level of introgression in the identified hybrid wild boar is equivalent to first‐generation hybrids until fifth‐generation backcrosses with wild boar. The distribution pattern of introgressed SNPs supported these assignments in four of nine hybrids. The other five hybrids are considered advanced‐generation hybrids, resulting from interbreeding among hybrid individuals. Three of nine hybrids were genetically associated with a different wild boar population than the one in which they were sampled. This discrepancy suggests that genetic introgression has occurred through the escape or release of an already hybridized farmed wild boar stock. We conclude that genetic introgression from domestic pigs into NW European wild boar populations is more recent and more common than expected and that genome‐wide SNP analysis is a promising tool to quantify recent hybridization in free‐living populations.
Question
Riparian vegetation and seed banks are the foundation of functional riparian zones, yet insight in the processes that explain their composition is limited. We tested three theories ...fundamental to dispersal and environmental filtering of riparian seed banks and vegetation. Combining these theories, we expected hydrochory to lead to increased species richness downstream in both soil seed bank and vegetation with accumulation restarting after a lake section, and geomorphological filtering to lead to higher similarity of seed bank and vegetation composition locally and within lakes, slow‐flowing sections and rapids, respectively, than between them.
Location
Svartån, a free‐flowing river in central Sweden.
Methods
We surveyed riparian vegetation and conducted a germination experiment on riparian soil seed bank cores from lakes, slow‐flowing sections and rapids. We combined these with trait data on seed dispersal syndromes, floating capacity of seeds and seed longevity. We analysed differences throughout the system with linear models and between process domains with Kruskal–Wallis tests and similarity in community composition with the Horn–Morisita similarity index.
Results
Our results indicated that species richness did not increase downstream and was relatively similar throughout lakes, slow‐flowing sections and rapids for both riparian seed banks and vegetation. Seed floating capacity was similar throughout these river sections, too, and seed longevity was higher in seed banks than in vegetation.
Conclusions
Geomorphology and hydrochory were not as important drivers in this area for riparian seed bank and vegetation composition as expected. In the area and on the scale studied here, other local and regional environmental factors and dispersal syndromes are more likely to be determinants of riparian dynamics and composition. Continued studies of riparian seed banks can help improve our understanding of riparian composition and functioning in the future.
We studied the effects of hydrology and geomorphology for seed dispersal and environmental filtering on riparian vegetation. Riparian seed bank and vegetation contained different species, but we found no clear effect of hydrochory. Geomorphologically different sections (lakes, slow‐flowing and rapid sections) were more similar to each other than expected, and differences in trait composition of seed bank and vegetation were mostly based on seed longevity.
Global impact models represent process-level understanding of how natural and human systems may be affected by climate change. Their projections are used in integrated assessments of climate change. ...Here we test, for the first time, systematically across many important systems, how well such impact models capture the impacts of extreme climate conditions. Using the 2003 European heat wave and drought as a historical analogue for comparable events in the future, we find that a majority of models underestimate the extremeness of impacts in important sectors such as agriculture, terrestrial ecosystems, and heat-related human mortality, while impacts on water resources and hydropower are overestimated in some river basins; and the spread across models is often large. This has important implications for economic assessments of climate change impacts that rely on these models. It also means that societal risks from future extreme events may be greater than previously thought.
Abstract
We present the H i eXtreme (HIX) galaxy survey targeting some of the most H i rich galaxies in the Southern hemisphere. The 13 HIX galaxies have been selected to host the most massive H i ...discs at a given stellar luminosity. We compare these galaxies to a control sample of average galaxies detected in the H i Parkes All Sky Survey (HIPASS). As the control sample is matched in stellar luminosity, we find that the stellar properties of HIX galaxies are similar to the control sample. Furthermore, the specific star formation rate and optical morphology do not differ between HIX and control galaxies. We find, however, the HIX galaxies to be less efficient in forming stars. For the most H i massive galaxy in our sample (ESO075-G006, log $M_{\rm H\,\small {I}}$ M⊙ = (10.8 ± 0.1)), the kinematic properties are the reason for inefficient star formation and H i excess. Examining the Australian Telescope Compact Array (ATCA) H i imaging and Wide Field Spectrograph (WiFeS) optical spectra of ESO075-G006 reveals an undisturbed galaxy without evidence for recent major, violent accretion events. A tilted ring fitted to the H i disc together with the gas-phase oxygen abundance distribution supports the scenario that gas has been constantly accreted on to ESO075-G006 but the high specific angular momentum makes ESO075-G006 very inefficient in forming stars. Thus, a massive H i disc has been built up.
Starch contains phosphate covalently bound to the C6-position (70 to 80% of total bound phosphate) and the C3-position (20 to 30%) of the glucosyl residues of the amylopectin fraction. In plants, the ...transient phosphorylation of starch renders the granule surface more accessible to glucan hydrolyzing enzymes and is required for proper starch degradation. Phosphate also confers desired properties to starch-derived pastes for industrial applications. In Arabidopsis thaliana, the removal of phosphate by the glucan phosphatase Starch Excess4 (SEX4) is essential for starch breakdown. We identified a homolog of SEX4, LSF2 (Like Sex Four2), as a novel enzyme involved in starch metabolism in Arabidopsis chloroplasts. Unlike SEX4, LSF2 does not have a carbohydrate binding module. Nevertheless, it binds to starch and specifically hydrolyzes phosphate from the C3-position. As a consequence, Isf2 mutant starch has elevated levels of C3-bound phosphate. SEX4 can release phosphate from both the C6-and the CS-positions, resulting in partial functional overlap with LSF2. However, compared with sex4 single mutants, the Isf2 sex4 double mutants have a more severe starch-excess phenotype, impaired growth, and a further change in the proportion of C3-and C6-bound phosphate. These findings significantly advance our understanding of the metabolism of phosphate in starch and provide innovative options for tailoring novel starches with improved functionality for industry.
Riparian zones are species-rich and functionally important ecotones that sustain physical, chemical and ecological balance of ecosystems. While scientific, governmental and public attention for ...riparian zones has increased over the past decades, knowledge on the effects of the majority of anthropogenic disturbances is still lacking. Given the increasing expansion and intensity of these disturbances, the need to understand simultaneously occurring pressures grows. We have conducted a literature review on the potential effects of anthropogenic pressures on boreal riparian zones and the main processes that shape their vegetation composition. We visualised the observed and potential consequences of flow regulation for hydropower generation, flow regulation through channelisation, the climate crisis, forestry, land use change and non-native species in a conceptual model. The model shows how these pressures change different aspects of the flow regime and plant habitats, and we describe how these changes affect the extent of the riparian zone and dispersal, germination, growth and competition of plants. Main consequences of the pressures we studied are the decrease of the extent of the riparian zone and a poorer state of the area that remains. This already results in a loss of riparian plant species and riparian functionality, and thus also threatens aquatic systems and the organisms that depend on them. We also found that the impact of a pressure does not linearly reflect its degree of ubiquity and the scale on which it operates. Hydropower and the climate crisis stand out as major threats to boreal riparian zones and will continue to be so if no appropriate measures are taken. Other pressures, such as forestry and different types of land uses, can have severe effects but have more local and regional consequences. Many pressures, such as non-native species and the climate crisis, interact with each other and can limit or, more often, amplify each other’s effects. However, we found that there are very few studies that describe the effects of simultaneously occurring and, thus, potentially interacting pressures. While our model shows where they may interact, the extent of the interactions thus remains largely unknown.
We demonstrate the frequency stabilization of a terahertz quantum-cascade laser (QCL) to the Lamb dip of the absorption line of a D
O rotational transition at 3.3809309 THz. To assess the quality of ...the frequency stabilization, a Schottky diode harmonic mixer is used to generate a downconverted QCL signal by mixing the laser emission with a multiplied microwave reference signal. This downconverted signal is directly measured by a spectrum analyzer showing a full width at half maximum of 350 kHz, which is eventually limited by high-frequency noise beyond the bandwidth of the stabilization loop.
A bulky cyclopentadienyl (Cp)‐based trioxorhenium compound was developed for the catalytic deoxydehydration of vicinal diols to olefins. The 1,2,4‐tri(tert‐butyl)cyclopentadienyl trioxorhenium (2) ...catalyst was synthesised in a two‐step synthesis procedure. Dirhenium decacarbonyl was converted into 1,2,4‐tri(tert‐butyl)cyclopentadienyl tricarbonyl rhenium, followed by a biphasic oxidation with H2O2. These two new three‐legged compounds with a ‘piano‐stool’ configuration were fully characterised, including their single crystal X‐ray structures. Deoxydehydration reaction conditions were optimised by using 2 mol % loading of 2 for the conversion of 1,2‐octanediol into 1‐octene. Different phosphine‐based and other, more conventional, reductants were tested in combination with 2. Under optimised conditions, a variety of vicinal diols (aromatic and aliphatic, internal and terminal) were converted into olefins in good to excellent yields, and with minimal olefin isomerisation. A high turnover number of 1400 per Re was achieved for the deoxydehydration of 1,2‐octanediol. Furthermore, the biomass‐derived polyols (glycerol and erythritol) were converted into their corresponding olefinic products by 2 as the catalyst.
In the bulk of it: Bulky 1,2,4‐tri(tert‐butyl)cyclopentadienyl trioxorhenium was studied as a catalyst for the deoxydehydration of different vicinal diols. Under optimised conditions, a variety of vicinal diols were converted into olefins in good to excellent yields, and with minimal olefin isomerisation. Biomass‐derived polyols were also converted into their corresponding olefinic products.
Population genetic studies focus on natural dispersal and isolation by landscape barriers as the main drivers of genetic population structure. However, anthropogenic factors such as reintroductions, ...translocations and wild x domestic hybridization may also have strong effects on genetic population structure. In this study we genotyped 351 Single Nucleotide Polymorphism markers evenly spread across the genome in 645 wild boar (Sus scrofa) from Northwest Europe to evaluate determinants of genetic population structure.
We show that wild boar genetic population structure is influenced by historical reintroductions and by genetic introgression from domestic pigs. Six genetically distinct and geographically coherent wild boar clusters were identified in the Netherlands and Western Germany. The Dutch Veluwe cluster is known to be reintroduced, and three adjacent Dutch and German clusters are suspected to be a result of reintroduction, based on clustering results, low levels of heterozygosity and relatively high genetic distances to nearby populations. Recent wild x domestic hybrids were found geographically widespread across clusters and at low frequencies (average 3.9%). The relationship between pairwise kinship coefficients and geographic distance showed male-biased dispersal at the population genetic level.
Our results demonstrate that wildlife and landscape management by humans are shaping the genetic diversity of an iconic wildlife species. Historical reintroductions, translocation and recent restocking activities with farmed wild boar have all influenced wild boar genetic population structure. The current trend of wild boar population growth and range expansion has recently led to a number of contact zones between clusters, and further admixture between the different wild boar clusters is to be expected.
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