Human activity and related land use change are the primary cause of accelerated soil erosion, which has substantial implications for nutrient and carbon cycling, land productivity and in turn, ...worldwide socio-economic conditions. Here we present an unprecedentedly high resolution (250 × 250 m) global potential soil erosion model, using a combination of remote sensing, GIS modelling and census data. We challenge the previous annual soil erosion reference values as our estimate, of 35.9 Pg yr
of soil eroded in 2012, is at least two times lower. Moreover, we estimate the spatial and temporal effects of land use change between 2001 and 2012 and the potential offset of the global application of conservation practices. Our findings indicate a potential overall increase in global soil erosion driven by cropland expansion. The greatest increases are predicted to occur in Sub-Saharan Africa, South America and Southeast Asia. The least developed economies have been found to experience the highest estimates of soil erosion rates.
Bs,d→ππ,πK,KK: status and prospects Fleischer, R.
European physical journal. C, Particles and fields,
10/2007, Letnik:
52, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Several years ago, it was pointed out that the U-spin-related decays Bd→π+π-, Bs→K+K- and Bd→π∓K±, Bs→π±K∓ offer interesting strategies for the extraction of the angle γ of the unitarity triangle. ...Using the first results from the Tevatron on the Bs decays and the B-factory data on Bu,d modes, we compare the determinations of γ from both strategies, study the sensitivity on U-spin-breaking effects, discuss the resolution of discrete ambiguities, predict observables that were not yet measured but will be accessible at LHCb, explore the extraction of the width difference ΔΓs from untagged Bs→K+K- rates, and address the impact of new physics. The data for the Bd→π+π-, Bs→K+K- system favour the BaBar measurement of direct CP violation in Bd→π+π-, which will be used in the numerical analysis and result in a fortunate situation, yielding γ=(66.6+4.3+4.0-5.0-3.0)°, where the latter errors correspond to a generous estimate of U-spin-breaking effects. On the other hand, the Bd→π∓K±, Bs→π±K∓ analysis leaves us with 26°≤γ≤70°, and points to a value of the Bs→π±K∓ branching ratio that is larger than the current Tevatron result. An important further step will be the measurement of mixing-induced CP violation in Bs→K+K-, which will also allow us to extract the B0s–B̄0s mixing phase unambiguously with the help of Bs→J/ψφ at the LHC. Finally, the measurement of direct CP violation in Bs→K+K- will make the full exploitation of the physics potential of the Bs,d→ππ,πK,KK modes possible.
As is well known, B0d,s–B̄0d,s mixing offers a profound probe into the effects of physics beyond the standard model. The data obtained at the e+e- B factories have already provided valuable insights ...into the Bd-meson system, and very recently also the B0s–B̄0s oscillation frequency ΔMs has been measured at the Tevatron. We give a critical discussion of the interpretation of these data in terms of model-independent new-physics parameters. We address in particular the impact of the uncertainties of the relevant input parameters, set benchmarks for their accuracies as required by future precision measurements at the LHC, and explore the prospects for new CP-violating effects in the Bs system. To complement our model-independent analysis, we also discuss the constraints imposed by the CDF measurement of ΔMs on popular models of new physics, namely scenarios with an extra Z’ boson and supersymmetry. We find that the new data still leave sizeable room for new-physics contributions to B0s–B̄0s mixing, which could be detected at the LHC.
•We formulated and analyze two eco-evo predator-prey models with different evolutionary trade-offs.•Coexistence is more likely when growth rate is affected by an evolving trait than when carrying ...capacity is.•Coexistence is more likely when the ratio of predator and prey speeds of adaptation is sufficiently high.
In recent decades, myriad studies have explored the population dynamics of coevolving populations of predator and prey. A variety of choices are made in these models: exponential or logistic prey growth in the absence of a predator, various forms of predator functional response, and uni- or bi-directional trait axes. In addition, some form of trade-offs are assumed in order to prevent run-away evolution of the prey and predator traits. While there is a considerable amount of theory regarding various forms of prey growth rates and predator functional responses, only a few studies have explored how different types of trade-offs affect predator-prey dynamics. Here, we compared two ditrophic coevolution models incorporating different trade-offs via dual effects of the prey trait on attack rate and either prey carrying capacity or intrinsic growth rate. We employed a standard dynamical systems approach to analyze the equilibrium conditions of each model and find conditions for non-equilibrium oscillatory coexistence. The exact effect of various parameters on the outcome of predator-prey interactions depends on whether the trade-offs affect the intrinsic growth rate or carrying capacity. In particular, coexistence is more likely when prey growth rate is affected by the evolving trait. In addition, in parameter regimes where cycles occur in both models, oscillations typically have larger periods and amplitudes when prey growth rate is affected by the evolving trait.
Ships’ ballast water (BW) commonly moves macroorganisms and microorganisms across the world’s oceans and along coasts; however, the majority of these microbial transfers have gone undetected. We ...applied high-throughput sequencing methods to identify microbial eukaryotes, specifically emphasizing the protistan parasites, in ships’ BW collected from vessels calling to the Chesapeake Bay (Virginia and Maryland, USA) from European and Eastern Canadian ports. We utilized tagged-amplicon 454 pyrosequencing with two general primer sets, amplifying either the V4 or V9 domain of the small subunit (SSU) of the ribosomal RNA (rRNA) gene complex, from total DNA extracted from water samples collected from the ballast tanks of bulk cargo vessels. We detected a diverse group of protistan taxa, with some known to contain important parasites in marine systems, including Apicomplexa (unidentified apicomplexans, unidentified gregarines, Cryptosporidium spp.), Dinophyta (Blastodinium spp., Euduboscquella sp., unidentified syndinids, Karlodinium spp., Syndinium spp.), Perkinsea (Parvilucifera sp.), Opisthokonta (Ichthyosporea sp., Pseudoperkinsidae, unidentified ichthyosporeans), and Stramenopiles (Labyrinthulomycetes). Further characterization of groups with parasitic taxa, consisting of phylogenetic analyses for four taxa (Cryptosporidium spp., Parvilucifera spp., Labyrinthulomycetes, and Ichthyosporea), revealed that sequences were obtained from both known and novel lineages. This study demonstrates that high-throughput sequencing is a viable and sensitive method for detecting parasitic protists when present and transported in the ballast water of ships. These data also underscore the potential importance of human-aided dispersal in the biogeography of these microbes and emerging diseases in the world’s oceans.
Microsatellite loci are highly informative genetic markers useful for population genetic studies, linkage mapping and parentage determination. Methods to identify novel microsatellite loci commonly ...use subtractive hybridization to enrich smallinsert genomic libraries for repeat sequences. A critical step in enrichment is attachment of an oligonucleotide linker to genomic DNA fragments so that repeat-containing sequences can be recovered by PCR for cloning. Current linkers and ligation methods rely on single restriction enzymes to size-fraction genomic DNA and generate complementary ends. These restriction enzyme/linker combinations are often speciesspecific, give poor recovery of repeat-enriched DNA and yield library inserts that are not a broad sample of the genome. We have developed a blunt-end linker, named SNX for its restriction sites, that allows the use of combinations of restriction enzymes to digest the majority of genomic DNA into the 200-1000-bp range. SNX is attached to genomic DNA with a simultaneous ligation/restriction reaction that is highly efficient and improves recovery of sequences after subtractive hybridization. SNX can be used for microsatellite enrichment in any species, since ligation is independent of the restriction enzymes used to size-fraction genomic DNA. These methods improve current repeat-enrichment strategies, resulting in representative small-insert libraries with a very high proportion of positive clones.
Conservation of wide‐ranging species, such as the African forest elephant (Loxodonta cyclotis), depends on fully protected areas and multiple‐use areas (MUA) that provide habitat connectivity. In the ...Gamba Complex of Protected Areas in Gabon, which includes 2 national parks separated by a MUA containing energy and forestry concessions, we studied forest elephants to evaluate the importance of the MUA to wide‐ranging species. We extracted DNA from elephant dung samples and used genetic information to identify over 500 individuals in the MUA and the parks. We then examined patterns of nuclear microsatellites and mitochondrial control‐region sequences to infer population structure, movement patterns, and habitat use by age and sex. Population structure was weak but significant, and differentiation was more pronounced during the wet season. Within the MUA, males were more strongly associated with open habitats, such as wetlands and savannas, than females during the dry season. Many of the movements detected within and between seasons involved the wetlands and bordering lagoons. Our results suggest that the MUA provides year‐round habitat for some elephants and additional habitat for others whose primary range is in the parks. With the continuing loss of roadless wilderness areas in Central Africa, well‐managed MUAs will likely be important to the conservation of wide‐ranging species. Utilización de Perfiles Genéticos de Elefantes Africanos para Inferir su Estructura Poblacional, Movimientos y Uso del Hábitat en un Paisaje con Conservación y Desarrollo en Gabón Resumenfgs
Biodiversity conservation strategies are increasingly focused on regions outside national protected areas, where animals face numerous anthropogenic threats and must coexist with human settlements, ...livestock, and agriculture. The effects of these potential threats are not always clear, but they could have profound implications for population viability. We used savannah elephants (Loxodonta africana) as a case study to assess the physiological stress associated with living in a human-livestock-dominated landscape. We collected samples over two 3-month periods in 2007 and 2008. We used fecal DNA to identify 96 individual elephants in a community conservation area (CCA) and measured fecal glucocorticoid metabolite (FGM) concentrations as a proxy for stress. The CCA is community Maasai land managed for livestock and wildlife. We compared the FGM concentrations from the CCA to FGM concentrations of 40 elephants in Amboseli National Park and 32 elephants in the Maasai Mara National Reserve, where human settlements and intense livestock grazing were absent. In the CCA, we found no significant individual differences in FGM concentrations among the elephants in 2007 (p = 0.312) or 2008 (p = 0.412) and no difference between years (p = 0.616). The elephants in the CCA had similar FGM concentrations to the Maasai Mara population, but Amboseli elephants had significantly lower FGM concentrations than those in either Maasai Mara or the CCA (Tukey pairwise test, p < 0.001), due primarily to females excreting significantly lower FGM relative to males (p = 0.025). In the CCA, there was no relation among female group size, average pairwise group relatedness, and average group FGM concentration. We found no clear evidence of chronic stress in elephants living on CCA communal land, which is encouraging for conservation strategies promoting the protection of animals living outside protected areas. Las estrategias de conservación se enfocan cada vez más hacia regiones fuera de áreas nacionales protegidas, donde los animales enfrentan numerosas amenazas antropogénicas y deben coexistir con asentamientos humanos, ganado y agricultura. Los efectos de esas amenazas potenciales no siempre son claros, pero podrían tener implicaciones profundas para la viabilidad poblacional. Utilizamos elefantes africanos (Loxodonta africana) como un estudio de caso para evaluar el estrés fisiológico asociado con vivir en un paisaje dominado por humanos y ganado. Recolectamos muestras en 2 períodos de 3 meses en 2007 y 2008. Utilizamos ADN fecal para identificar a 96 elefantes individuales en un área de conservación comunitaria (ACC) y medimos las concentraciones del metabolito glucocorticoide fecal (MGF) como un indicador de estrés. El ACC es tierra Maasai comunitaria manejada para ganado y vida silvestres. Comparamos las concentraciones de MGF en el ACC con las concentraciones de MGF de 40 elefantes del Parque Nacional Amboseli y 32 elefantes de la Reserva Nacional Maasai Mara, donde no hay asentamientos humanos ni pastoreo intensivo. En el ACC, no encontramos diferencias individuales significativas en las concentraciones de MGF entre los elefantes en 2007 (p = 0.312) ni 2008 (p = 0.412) ni entre años (p = 0.616). Los elefantes en el ACC tuvieron concentraciones similares de MGF a la población de Maasai Mara, pero los elefantes de Amboseli tuvieron concentraciones de MGF significativamente menores que las de Maasai Mara o el ACC. (prueba pareada de Tukey, p < 0.001), debido principalmente a que las hembras excretan significativamente menos MGF que los machos (p = 0.025). En el ACC, no hubo relación entre el tamaño del grupo de hembras, la similitud promedio de grupos pareados, ni la concentración de MGF promedio del grupo. No encontramos evidencias claras de estrés crónico en elefantes viviendo en el ACC, lo cual es alentador para las estrategias de conservación que promueven la protección de animales que viven fuera de áreas protegidas.
Female preference for local cultural traits has been proposed as a barrier to breeding among animal populations. As such, several studies have found correlations between male bird song dialects and ...population genetics over relatively large distances. To investigate whether female choice for local dialects could act as a barrier to breeding between nearby and contiguous populations, we tested whether variation in male song dialects explains genetic structure among eight populations of rufous‐collared sparrows (Zonotrichia capensis) in Ecuador. Our study sites lay along a transect, and adjacent study sites were separated by approximately 25 km, an order of magnitude less than previously examined for this and most other species. This transect crossed an Andean ridge and through the Quijos River Valley, both of which may be barriers to gene flow. Using a variance partitioning approach, we show that song dialect is important in explaining population genetics, independent of the geographic variables: distance, the river valley and the Andean Ridge. This result is consistent with the hypothesis that song acts as a barrier to breeding among populations in close proximity. In addition, songs of contiguous populations differed by the same degree or more than between two populations previously shown to exhibit female preference for local dialect, suggesting that birds from these populations would also breed preferentially with locals. As expected, all geographic variables (distance, the river valley and the Andean Ridge) also predicted population genetic structure. Our results have important implications for the understanding whether, and at what spatial scale, culture can affect population divergence.
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