466 research outputs found

    Macroscelideans (Myohyracinae and Rhynchocyoninae) from the late Oligocene Nsungwe formation of the Rukwa Rift Basin, southwestern Tanzania

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    The fossil record of macroscelidean mammals is notoriously patchy, with a significant spatial and temporal gap separating faunas from the early Oligocene localities of northern Africa and the early Miocene localities of eastern and southern Africa. Here we describe fossil macroscelideans representing Myohyracinae and Rhynchocyoninae recovered from a rift-fill sequence of richly fossiliferous sandstones in the late Oligocene Nsungwe Formation in the Rukwa Rift Basin of southwestern Tanzania. Radiometrically dated to 25.2 Ma, a new Palaeogene myohyracine taxon (Rukwasengi butleri) is represented by a partial maxilla (RRBP 05409) preserving a lightly worn M2-M3. The M2 exhibits a less hypsodont and mesiodistally elongate morphology than the early Miocene Myohyrax oswaldi, and the three-rooted M3 exhibits a tiny mesially positioned fossette. A new rhynchocyonine (Oligorhynchocyon songwensis) is represented by specimens more brachyodont than the early Miocene Miorhynchocyon. Taken together these finds document a rare window into macroscelidean evolutionary history with diversification of the group near the Palaeogene-Neogene Transition (PNT). Continued exploration offers a refined perspective on mid-Cenozoic faunal and ecosystem dynamics on continental Africa, expanding opportunities for recognising trends in palaeobiological diversity across habitat types and through time

    Living at the edge: home range patterns of the Buraiga Chimpanzee Community, Kibale National Park, Uganda

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    Data on space-use patterns are essential for understanding species ecology and conservation. Individual chimpanzee communities are known to vary in home range size and habitat use dynamics, reflecting site-specific strategies to differences in resource availability on different landscapes. Here we present home range estimates for the Buraiga chimpanzees of Kibale National Park, Uganda, a community of eastern chimpanzees (Pan troglodytes schweinfurthii) living within the largest remaining population fragment in Uganda. The Buraiga chimpanzees are currently undergoing habituation for research and tourism under the direction of the Uganda Wildlife Authority (UWA). We analyzed 15 months of GPS data (August 2019 – March 2020, and January – July 2022), calculating overall and seasonal home range and core area estimates with two methods, minimum convex polygon (MCP) and kernel density estimates (KDE). Home range was estimated to cover an area of 15.77 km2 (95% KDE), and 24.90 km2 (100% MCP). Additionally, we found that 15.82% of the Buraiga chimpanzee’s home range overlaps with community-managed land, primarily the Kanyanchu Swamp corridor and adjacent agricultural land. Seasonally, we found that Buraiga chimpanzees used a larger area during dry season months, compared with rainy season months. Documenting how great ape populations utilize increasingly anthropogenically influenced landscapes is important in order to facilitate long-term survival in the face of climate change, habitat fragmentation, and other ongoing threats

    Impact of Sampling Frequency on Annual Load Estimation of Total Phosphorus and Total Suspended Solids

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    The determination of sediment and nutrient loads is typically based on the collection and analysis of grab samples. The frequency and regularity of traditional sampling may not provide representation of constituent loading, particularly in systems with flashy hydrology. At two sites in the Little Bear River, Utah, continuous, high-frequency turbidity was used with surrogate relationships to generate estimates of total phosphorus and total suspended solids concentrations, which were paired with discharge to estimate annual loads. The high frequency records were randomly subsampled to represent hourly, daily, weekly, and monthly sampling frequencies and to examine the effects of timing, and resulting annual load estimates were compared to the reference loads. Higher frequency sampling resulted in load estimates that better approximated the reference loads. The degree of bias was greater at the more hydrologically responsive site in the upper watershed, which required a higher sampling frequency than the lower watershed site to achieve the same level of accuracy in estimating the reference load. The hour of day and day of week of sampling impacted load estimation, depending on site and hydrologic conditions. The effects of sampling frequency on the determination of compliance with a water quality criterion were also examined. These techniques can be helpful in determining necessary sampling frequency to meet the objectives of a water quality monitoring program

    Citizens without nations

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    To broach the question of whether citizenship could exist without (or beyond) community, this paper discusses genealogies of citizenship as membership that binds an individual to the community of birth (of the self or a parent). It is birthright as fraternity that blurs the boundary between citizenship and nationality. After briefly discussing recent critical studies on birthright citizenship (whether it is civic or ethnic or blood or soil) by Ayelet Shachar and Jacqueline Stevens, the paper discusses three critical genealogies of the relationship between birthright and citizenship by Max Weber, Hannah Arendt, and Michel Foucault. Although each provides a critical perspective into the question, Weber reduces citizenship to fraternity with nation and Arendt reduces citizenship to fraternity with the state. It is Foucault who illustrates racialization of fraternity as the connection between citizenship and nationality. Yet, since Foucault limits his genealogical investigations to the 18th and 19th centuries, a genealogy of fraternity of what he calls an immense biblical and Greek tradition remains for Derrida to articulate as a question of citizenship

    Behavior and diet of the Critically Endangered Eulemur cinereiceps in Manombo forest, southeast Madagascar

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    Manombo Special Reserve is a parcel of rainforest along the southeastern coast of Madagascar, containing eight lemur species, including the White-collared brown lemur (Eulemur cinereiceps [Eulemur albocollaris]). Following a drastic cyclone in the region in January of 1997, the population of E. cinereiceps at Manombo was reduced by half. Results indicate that individuals of this critically endangered species at Manombo consume a total of 54 plant species belonging to 24 families, with over two-thirds of the diet comprised of ripe and unripe fruits. White-collared brown lemurs also opportunistically feed on novel food items and invasive plants in their recovering habitat. We report the first record of E. cinereiceps consuming a shelf fungus species growing on invasive trees. During feeding, lemurs tore pieces of the fungus from the trees with their hands and mouth (chewing cycle duration mean 0.28 s; SD 0.01). White-collared brown lemurs also consumed spicy fruits of a non-native plant species (Aframomum angustifolium) growing in highly disturbed open areas. Feeding bouts typically began by stripping away the outer covering with the anterior dentition, with pulp and seeds then consumed (chewing cycle duration mean 0.22 s; SD 0.005). This is the first record of consumption of either of these resources for any lemur species at Manombo. Ability to feed on items like A. angustifolium may permit E. cinereiceps to avoid competition with other species in this highly degraded forest environment.RÉSUMÉ La Réserve Spéciale de Manombo est un fragment de forêt dense humide de basse altitude et située le long de la côte Sud-est de Madagascar. Cette partie de forêt abrite au total huit espèces de lémuriens, y compris le Lémur à collier blanc (Eulemur cinereiceps [Eulemur albocollaris]). Le passage dramatique du cyclone Gretelle dans la région en janvier 1997 a réduit de moitié la taille de la population d’E. cinereiceps dans sa zone de distribution. Les résultats des études effectuées sur les individus restants de cette espèce, qui est classée comme Gravement Menacée, permettent d’énumérer un total de 54 espèces de plantes appartenant à 24 familles qui sont consommées par l’espèce. D’autre part, deux tiers du régime alimentaire d’E. cinereiceps sont représentés par des fruits mûrs ou non. Le Lémur à collier blanc consomme occasionnellement une quantité assez importante de plantes envahissantes pour assurer ses besoins nutritifs, ce qui n’est pas habituel dans l’histoire naturelle de la vie des lémuriens. La présente étude constitue également la première observation de consommation d’une espèce inconnue de champignon par les représentants d’E. cinereiceps. Dans le présent cas, ledit champignon venait juste de pousser sur un pied mort de Cecropia peltata, une espèce allogène et envahissante de la région. Durant la prise de nourriture, l’animal a arraché des morceaux du champignon sur l’arbre mort avec la main et puis la bouche. La partie consommée a été mâchée par l’animal pendant une période de 0,28 s. Le Lémur à collier blanc consomme aussi des fruits épicés d’une espèce de plante allogène (Aframomum angustifolium) qui ne pousse que dans des zones ouvertes et extrêmement dégradées. La prise de nourriture sur cette espèce de plante commence par l’enlèvement de la partie dure du fruit, pour cela l’animal utilise ses dents antérieures très puissantes, puis il tire soigneusement en même temps avec ses dents et sa langue la partie charnue et les graines. Cette prise de nourriture s’effectue pendant une période d’environ 0,22 s. C’était la première fois dans l’histoire des lémuriens de Manombo que des observations ont été effectuées sur un animal en train de manger des espèces de plantes inhabituelles. L’aptitude de manger des espèces de plantes telle que A. angustifolium pourrait permettre à E. cinereiceps d’éviter la compétition avec les autres espèces de lémuriens vivant dans cet environnement dégradé

    Enhanced detection of groundwater contamination from a leaking waste disposal site by microbial community profiles

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    Groundwater biogeochemistry is adversely impacted when municipal solid waste leachate, rich in nutrients and anthropogenic compounds, percolates into the subsurface from leaking landfills. Detecting leachate contamination using statistical techniques is challenging because well strategies or analytical techniques may be insufficient for detecting low levels of groundwater contamination. We sampled profiles of the microbial community from monitoring wells surrounding a leaking landfill using terminal restriction fragment length polymorphism (T-RFLP) targeting the 16S rRNA gene. Results show in situ monitoring of bacteria, archaea, and the family Geobacteraceae improves characterization of groundwater quality. Bacterial T-RFLP profiles showed shifts correlated to known gradients of leachate and effectively detected changes along plume fringes that were not detected using hydrochemical data. Experimental sediment microcosms exposed to leachate-contaminated groundwater revealed a shift from a -Proteobacteria and Actinobacteria dominated community to one dominated by Firmicutes and δ-Proteobacteria. This shift is consistent with the transition from oxic conditions to an anoxic, iron-reducing environment as a result of landfill leachate-derived contaminants and associated redox conditions. We suggest microbial communities are more sensitive than hydrochemistry data for characterizing low levels of groundwater contamination and thus provide a novel source of information for optimizing detection and long-term monitoring strategies at landfill sites. Copyright 2010 by the American Geophysical Union

    Palaeontological evidence for an Oligocene divergence between Old World monkeys and apes

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    Apes and Old World monkeys are prominent components of modern African and Asian ecosystems, yet the earliest phases of their evolutionary history have remained largely undocumented(1). The absence of crown catarrhine fossils older than similar to 20 million years (Myr) has stood in stark contrast to molecular divergence estimates of similar to 25-30 Myr for the split between Cercopithecoidea (Old World monkeys) and Hominoidea (apes), implying long ghost lineages for both clades(2-4). Here we describe the oldest known fossil 'ape', represented by a partial mandible preserving dental features that place it with 'nyanzapithecine' stem hominoids. Additionally, we report the oldest stem member of the Old World monkey clade, represented by a lower third molar. Both specimens were recovered from a precisely dated 25.2-Myr-old stratum in the Rukwa Rift, a segment of the western branch of the East African Rift in Tanzania. These finds extend the fossil record of apes and Old World monkey swell into the Oligocene epoch of Africa, suggesting a possible link between diversification of crown catarrhines and changes in the African landscape brought about by previously unrecognized tectonic activity(5) in the East African rift system

    Ammonia exposure promotes algal biomass in an ombrotrophic peatland

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    Nitrogen pollution affects many peatlands with consequences for their biodiversity and ecosystem function. Microorganisms control nutrient cycling and constitute most of the biodiversity of peatlands but their response to nitrogen is poorly characterised and likely to depend on the form of deposition. Using a unique field experiment we show that ammonia exposure at realistic point source levels is associated with a general shift from heterotrophic (bacteria and fungi) to autotrophic (algal) dominance and an increase in total biomass. The biomass of larger testate amoebae increased, suggesting increased food supply for microbial predators. Results show the widespread impacts of N pollution and suggest the potential for microbial community-based bioindicators in these ecosystems

    Regional trends in soil acidification and exchangeable metal concentrations in relation to acid deposition rates

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    The deposition of high levels of reactive nitrogen (N) and sulphur (S), or the legacy of that deposition, remain among the world's most important environmental problems. Although regional impacts of acid deposition in aquatic ecosystems have been well documented, quantitative evidence of wide-scale impacts on terrestrial ecosystems is not common. In this study we analysed surface and subsoil chemistry of 68 acid grassland sites across the UK along a gradient of acid deposition, and statistically related the concentrations of exchangeable soil metals (1 M KCl extraction) to a range of potential drivers. The deposition of N, S or acid deposition was the primary correlate for 8 of 13 exchangeable metals measured in the topsoil and 5 of 14 exchangeable metals in the subsoil. In particular, exchangeable aluminium and lead both show increased levels above a soil pH threshold of about 4.5, strongly related to the deposition flux of acid compound
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