Eastern Edge Research Articles

New distribution records of the coconut crab (Birgus latro) in eastern Polynesia on Oeno Atoll, Henderson Island, and Ducie Atoll, Pitcairn Islands

Coconut (or robber) crabs (Birgus latro) are found throughout the Indo-Pacific, including as far east as the Gambier Islands, French Polynesia, though the eastern edge of their range is poorly defined. Here, we document narratives and occurrences of coconut crabs on Oeno Atoll, Henderson Island, and Ducie Atoll in the Pitcairn Islands, which extends the currently known eastern limit of coconut crabs’ range by >600 km. Crabs are not abundant on the islands, but suitable habitat and prey are available, so larger populations may be present, particularly on Henderson Island. Edge-of-range populations are often the most susceptible to pressures, but the remoteness of the Pitcairn Islands may shield coconut crabs from threats present elsewhere in the Indo-Pacific region.

Evolution of the northeastern margin of the Kazakhstan paleocontinent: results of petro-geochemical study of sedimentary and volcanogenic-sedimentary rocks of the Zharma-Saur island arc zone

We carried out studies of petrography, petrochemistry, geochemistry and Nd-isotopy of sedimentary and volcanic rocks, as well as U‒Pb dating of detrital zircons from sandstones and tuff sandstones of four stratigraphic units of the Zharma-Saur island arc zone, located in the Middle-Late Paleozoic near the north eastern (in modern coordinates) edge of the Kazakhstan paleocontinent. The data obtained, geological structure and analysis of discriminant diagrams indicate that the formation of sandstones of the Givetian‒Frasnian sequence was the result of erosion and destruction of the Early Paleozoic igneous complexes of the Chingiz-Tarbagatai zone of the Kazakhstan paleocontinent. Tuff sandstones of the Koyanda formation of the Tournaisian stage and the Tersairyk formation of the Visean stage, distributed within the Vorontsov-Saur subzone, are mainly a product of rock destruction and volcanic activity of the Zharma-Saur volcanic arc. The feeding provinces for the sedimentary rocks of the Kokon formation of the Visean stage, which occupies most of the Zharma-Sarsazan subzone, were simultaneously the Caledonides of the Chingiz-Tarbagatai zone and the Early Carboniferous volcanogenic complexes of the Zharma-Saur volcanic arc. Our data show that the Zharma-Saur arc developed near the northeastern margin of the Kazakhstan paleocontinent at the end of the Late Devonian‒in the Early Carboniferous period.

Assessment of the oil and gas potential of the eastern edge of the Northern Ustyurt using new geophysical data

Purpose. Detailed substantiation of the geological structure of the eastern edge of the Northern Ustyurt, clarification of modern geological and geophysical data, as well as highlighting the mainstages of evaluating the results of exploration work to confirm the oil and gas potential and subsequent exploitation of the fields. Methodology. The authors used the following scientific methods: generalization – to systematize scientific provisions; analogy and comparison – to characterize deflection in different periods; analysis and synthesis – to substantiate geological and geophysical data; algorithmmization – to determine conceptual provisions regarding the assessment of the oil and gas bearing capacity of the trough. Findings. In order to achieve the goals, the indicators of oil and gas capacity in the areas of the eastern side of the Northern Ustyurt of different geological ages were substantiated. The geological and geophysical features of the basin dating back to 2010 compared to modern refinement of geological data were characterized. The productive and unproductive structures of the eastern side of the Northern Ustyurt are characterized, taking into account the showing of oil and gas based on deposits of different geological ages. The importance of conducting geological exploration and creating corresponding cartographic materials is justified, followed by the design of predictive graphical models, geological sections, and a detailed plan of the territory. Originality. The influence of high hydro carbon generation rates on the further identification of “oil windows” has been substantiated for the first time. The hierarchical levels of predicting the oil and gas content of the trough are identified. The necessity of improving the mechanisms for assessing oil and gas content is substantiated. Practical value. The substantiation of the features of the assessment of the oil and gas content of the of the eastern edge of the Northern Ustyurt, which should be based on forecasting promising areas of prospecting, is the key to distinguishing between productive and unproductive objects, determining their real scale and directing investment flow precisely to promising areas with minimal environmental and economic losses.

Miocene to Quaternary evolution of the northern Danube Basin: a review of geodynamics, depositional systems and stratigraphy

This review aims to present an updated lithostratigraphic framework of the northern Danube Basin in Slovakia, consistent with recent shifts in geochronology and depositional system redefinitions based on sedimentology and seismic stratigraphy. Several transgressive–regressive sequences are distinguished: The Lower Badenian (Middle Miocene), represented by the Špačince Fm, mainly occurred in peripheral Blatné and Želiezovce sub-basins. The central part of the Danube Basin formed an elevation during this period, coinciding with the onset of intermediate volcanic activity. The Upper Badenian (Middle Miocene), encompassed within the Pozba Fm, saw the flooding of the central Danube Basin, signifying a change in transport direction. The inception of this cycle is well constrained by recently published multiple 40 Ar/ 39 Ar dating to c. 13.8 Ma. The Sarmatian deposition (Middle Miocene), characterized by the Vráble Fm, also occurred in newly significantly deepened Komjatice and Rišňovce sub-basins, coinciding with a gradual cessation of calc-alkaline volcanism, observed only at the basin's eastern edge. The Pannonian (Upper Miocene) deposition includes lacustrine Ivanka, deltaic Beladice and alluvial Volkovce formations, representing interconnected depositional systems prograding towards Lake Pannon. The subsequent evolution entails a post-rift stage (9.5–6 Ma), primarily marked by the alluvial Volkovce Fm deposition, and basin inversion, with alluvial deposition mostly confined to the basin centre and differentially eroded basin margins (from 6 Ma to the present).

Accuracy evaluation and comparison of GSMaP series for retrieving precipitation on the eastern edge of the Qinghai-Tibet Plateau

Study RegionMin River Basin on the eastern Qinghai-Tibet Plateau. Study FocusPrecipitation is critical for hydrological processes, making accurate data essential for water management and flood forecasting. Satellite precipitation products offer valuable high-resolution spatiotemporal information, with the GSMaP series being widely used. However, comprehensive evaluations of different versions are limited. This study assesses the accuracy of Gauge and MVK products (versions 06, 07, and 08) across spatial and temporal scales and evaluates their performance in detecting precipitation events of varying intensities. New Hydrological Insights for the Study Region(1) GSMaP versions 06 and 07 exhibit higher detection rates for precipitation events, with POD values exceeding 0.8, while version 08 has a lower false alarm rate, with FAR values below 0.15. (2) GSMaP products are more successful in capturing precipitation events during the rainy season than the dry season. (3) With increasing elevation, the Gauge product consistently maintains a high hit rate and reduced false alarm rate, whereas the MVK product's hit rates improve. (4) For different rainfall intensities, GSMaP products more accurately detect moderate and heavy rain events, with the Gauge product outperforming the MVK product in terms of accuracy. These insights enhance the understanding of GSMaP product performance on eastern edge of the Qinghai-Tibet Plateau, aiding in improved water management practices.

Northward drift of the Burma Terrane with India during the Cenozoic and implications for the India–Asia collision

The past location of the Burma Terrane during the convergence of the Indian and Asian tectonic plates is key to unravelling the regional geodynamic, palaeoenvironmental and palaeobiogeographical history of the eastern edge of the Himalayan orogen. Palaeomagnetic data provide the ability to constrain the location of the Burma Terrane, but it has been very difficult to find rocks with palaeomagnetic records of primary characteristic remanent magnetizations. We present here new palaeomagnetic results spanning the Paleocene to late middle Eocene within the Burma Terrane, complementing palaeolatitudes previously established from Late Cretaceous intrusive rocks and late middle Eocene sedimentary rocks. Our palaeomagnetic data indicate that the Burma Terrane remained at equatorial latitudes during the Paleocene and early Eocene, at a considerable distance from the South Asian margin. In addition, palaeomagnetic results from mid- to late Eocene sedimentary rocks yield a predominantly north–south orientation of the Burma Terrane over the past 45 Myr, showing that it was not part of the NW–SE-oriented Sundaland margin before its collision with India. Our results support collision models involving a Trans-Tethyan subduction system during the Late Cretaceous and early Paleocene. We propose that this system incorporated the Burmese volcanic arc and continental fragments of Argoland before drifting north with India towards Asia. The new palaeogeographical model considers a reduced amount of oblique subduction of the Indian plate below Burma during the Cenozoic. A possible source of sediments filling the thick Myanmar basins from the Gangdese belt during the Eocene supports the hypothesis of an India–Asia collision around ∼50 Ma. The new palaeogeography supporting the formation of the Myanmar Cretaceous amber on an isolated Trans-Tethyan Arc is also a key element in discussions of the palaeobiogeographical evolution of the numerous faunas it contains.

Identification of subsurface archaeology at Mutaredh, United Arab Emirates, using ground penetrating radar

The United Arab Emirates holds great historical importance, as evidenced by many archaeological sites, such as the Jebel Hafit Tombs and the Hili Archeological Park in Al Ain. At the western edge of Mutaredh Oasis, a major new archaeological site was discovered in 2023 during a construction project. Several important archeological features have been documented, including an earthen mosque and boundary walls, Iron Age irrigation systems, and a circular stone tomb dating to the Bronze Age. However, the eastern edge of the Mutaredh site has remained unexplored to date. Ground Penetrating Radar (GPR) has been proven to be a successful method in mapping archaeological remains. Accordingly, a high-resolution GPR survey was carried out to identify the continuity of the unearthed archeological elements and delineate new unexplored features. A comprehensive 3D model of buried archaeological features was constructed using the acquired high-resolution GPR data in the eastern part of the Mutaredh site. Several selected anomalies have been observed, similar to the uncovered features in the western part of the Mutaredh site and structures documented in other nearby archaeological sites. The geometry and extension of these anomalies have enabled the possible identification of a further two Bronze Age circular tombs, as well as the delineation of a system of water channels (falaj), and irrigation networks with tree pits from the Iron Age. Moreover, walls probably belonging to the Late Islamic Age are identified. These findings suggest that Mutaredh has been a site of intensive human activity from the Bronze Age through to the Late Islamic period. Given the density of identified anomalies, further significant features are anticipated to lie buried in the immediate surrounding areas, promising continued insights into the area’s rich archaeological heritage. The findings of this study may guide archaeologists to specific locations and assist in selecting the most appropriate excavation techniques for the verification stage.

Statistical Characteristics of Snowfall on the Tibetan Plateau Affected by TCs Over the Bay of Bengal: An Observational Analysis

ABSTRACTIn this study, the characteristics of tropical cyclones (TCs) over the Bay of Bengal (BoB) that affect snowfall on the Tibetan Plateau (TP) and spatiotemporal distribution of snowfall related to BoB TCs are statistically analysed by using multi‐sources data from 1981 to 2020, with partitioning TC‐influenced snowfall by tracking cloud clusters. The results show that 141 TCs formed during the 40‐year period of 1981–2020, of which about 35% (50 TCs) impacted snowfall at 83% of meteorological stations on the TP during their northward or westward movement, and the average distance between the TC centre and the snowfall stations is 1277 km. The proportion of snowfall‐related TC frequency shows a significantly decreasing trend with a predominant cycle of 10a. The TC‐influenced snowfall frequency (SF), precipitation amount (PA) on a snowfall day and snow depth (SD) during 1981–2020 all show a non‐significant weak decreasing trend, while TC‐influenced snowfall is significantly increased in the eastern and southern edges of Xizang, western Sichuan and the southern margin of Qinghai. PA and SD in December account for more than 75% and 55% of the monthly total, respectively. The spatial pattern of PA could be objectively categorised into west‐type (24%) and southeast‐type (76%). The moisture transported by the BoB TC and a southerly jet stream formed between the trough and the western Pacific subtropical high (WPSH), the convergence of cold air and warm–moist airstream over the TP and the change in position of the south Asian high in the upper troposphere are significant factors causing the different spatial distribution. The results can provide reference for TC‐related snowfall, SD prediction and disaster assessment on the TP.

Peripheral Population Status and Habitat Suitability Assessment of the Kiang (Equus kiang) on the Eastern Tibetan Plateau

Shiqu County, Sichuan Province, forms the eastern edge of the distribution area of the kiang (Equus kiang). It is important to assess the population and habitat status of peripheral populations, as these play a significant role in the development of conservation strategies for kiangs. Based on field transect data collected from July to August 2023, this study predicted the suitable habitat distribution of kiangs in Shiqu County using a MaxEnt model and estimated the population size and density using the ‘Distance’ package. Additionally, it analyzed the responses of the group size of kiangs to environmental factors in Shiqu County. The results showed that the area of suitable habitat for kiangs is 3402.45 km2, accounting for 13.51% of the total area of Shiqu County. The estimated population was 1395.00 ± 272.20, with a population density of 0.41 ± 0.08/km2. Additionally, the group size of kiangs was significantly positively correlated with the distance from the road and grazing site. The distance from the grazing site, elevation, and temperature annual range are the main environmental factors affecting the distribution of kiangs. This study initially revealed the peripheral population Status and suitable habitat of the kiang on the eastern Tibetan Plateau, and the potential threat of grazing interference and road obstruction. The research results can provide a scientific reference for the population and habitat protection of kiangs in this area.

Microphysical Evolution in Mixed-Phase Midlatitude Marine Cold-Air Outbreaks

Abstract Five cold-air outbreaks are investigated with aircraft offshore of continental northeast America. Flight paths aligned with the cloud-layer flow from January through March span cloud-top temperatures from −5° to −12°C, in situ liquid water paths of up to 500 g m−2, while in situ cloud droplet number concentrations exceeding 500 cm−3 maintain effective radii below 10 μm. Rimed ice is detected in the four colder cases within the first cloud pass. After further fetch, ice particle number concentrations reaching 2.5 L−1 support an interpretation that secondary ice production is occurring. Rime splintering is clearly evident, with dendritic growth increasing ice water contents within deeper clouds with colder cloud-top temperatures. Buoyancy fluxes reach 400–600 W m−2 near the Gulf Stream’s western edge, with 1-s updrafts reaching 5 m s−1 supporting closely spaced convective cells. Near-surface rainfall rates of the three more intense cold-air outbreaks are a maximum near the Gulf Stream’s eastern edge, just before the clouds transition to more open-celled structures. The milder two cold-air outbreaks transition to lower-albedo cumulus with little or no precipitation. The clouds thin through cloud-top entrainment. Significance Statement Cold-air outbreaks off of the eastern U.S. seaboard are visually spectacular in satellite imagery, with overcast, high-albedo clouds transitioning to more broken cloud fields. We use data from the recent NASA Aerosol Cloud Meteorology Interactions over the Western Atlantic Experiment (ACTIVATE) aircraft campaign to examine the microphysics and environmental context of five such outbreaks. We find the clouds are not ice-deprived, but updrafts still supply significant liquid water. Cloud transitions are encouraged through near-surface rain for the deeper clouds, and otherwise, clouds thin and break through mixing in drier air from above. These observations support understanding and further modeling examining how mixed-phase cloud microphysics affect cloud reflectivity and surface rainfall rates, important for both weather and climate forecasting.

Dayside Magnetic Depression Following Interplanetary Shock Arrivals During the February 1958 and July 1959 Superstorms

AbstractThe present study investigates mid‐ and low‐latitude ground magnetic disturbances observed following the arrival of three interplanetary (IP) shocks during the super‐geomagnetic storms of February 1958 and July 1959. One may expect that after IP shocks, the H (northward) magnetic component increases globally but especially on the dayside. However, in each event, the H component was depressed sharply for 1–2 hr in the dawn‐to‐noon sector, whereas it increased in other local time (LT) sectors. Observed magnetic deflections suggest that there existed field‐aligned currents (FACs) flowing into and out of the auroral zone around the western and eastern edges of the LT sector of the dayside H depression. These features strongly suggests that the observed H depression was a remote effect of a R1‐sense FAC system. It was previously reported that similar ground magnetic disturbances were observed after the SSC of the 2003 Halloween storm, which reveals striking similarities to the well‐known H depression observed at Colaba during the 1859 Carrington storm. It is therefore suggested that the external driving behind IP shocks, especially those associated with major storms, is most optimum for the sharp reduction of the dayside H component through the formation and intensification of the dayside FAC system. Associated magnetic disturbances are considered to be larger in magnitude with increasing magnetic latitude, and oriented azimuthally as well as meridionally. Such magnetic disturbances in dayside midlatitudes may not be discussed very often as a target of space weather, but their potential impacts on ground infrastructures probably require closer attention.

Evidence of War on the Settlements of a Scythian Era in the Middle Don Region

Introduction. Two groups of people, differing in social status and material culture, occupied the middle part of the Don basin, representing the eastern edge of the Forest-Steppe Scythia, in the 6th – 3rd centuries BC. One is known from the few barrow necropolises, the materials of which characterize the nomadic and highly militarized way of life of the people buried there. The other one united sedentary farmers and cattle breeders, whose hillforts and not-strengthened settlements show evidence of predominantly peaceful occupations. Methods and materials. The article systematizes data to give an idea of the role of war in the lives of the main part of the population of the Don Forest Steppe. On 22 household monuments, only 77 objects of offensive arms (mainly arrowheads) and even fewer details of the equipment of the soldier rider are found. In the settlements of cemetery funeral complexes, the finds of weapons are single. Particular attention is deserved by the traces of fire recorded in defensive shafts in 25 hillforts. Analysis. Judging from the archaeological context, only some of the settlement finds were related to military clashes. Some things were part of the cult complexes. Fires, which led to the destruction and subsequent radical strengthening of fortifications, clearly occurred due to a few but catastrophic conflicts. Results. Clashes in the settlements of the Don Forest Steppe occurred episodically throughout the era and were obviously associated with periods of instability in Scythia. However, the sedentary population of the region was only to a small extent involved in the conflict processes of the past.

Detrital zircon U–Pb geochronology of the trench-fill sandstone on the Cretaceous Shimanto accretionary complex in SW Japan: Implications for provenance and igneous activity in the eastern edge of East Asia

Cretaceous igneous rocks are widely distributed in the East Asian margin, and their formation is due to the large-scale migration of igneous activity areas from the continental interior to near the subduction margin. Detrital zircon U–Pb ages of trench-fill sandstones of the Shimanto accretionary complex in the Akaishi Mountains of southwest Japan can provide information on eroded igneous rocks, and their location at the eastern edge of East Asia makes them essential for better understanding the intensity and migration of the igneous activity. As a result of the dating, the Cretaceous zircons in the trench-fill sandstones were found to increase dramatically in the middle Cretaceous and to be abundant in the Late Cretaceous. In addition, these large amounts of Cretaceous zircons were found to be derived from igneous rocks such as the Abukuma Granites and Ryoke Granites distributed in the proto-Japan arc. These results indicate that migration of igneous activity from the continental side reached the eastern edge of East Asia in the middle Cretaceous and that large-scale igneous activity continued to occur in the eastern edge of East Asia until the Late Cretaceous. Thus, the detrital zircon age spectra in trench-fill sediments provide a clear picture of the degree of igneous activity in the source area and migration of the igneous activity on active continental margins.

Application of major ions and Sr isotopes to indicate the evolution of river water and shallow groundwater chemistry in a typical endorheic watershed, northwestern China

Studying the hydrochemical evolution of river water and groundwater is vital for comprehending complex regional hydrological cycles and managing water resources. An investigation of hydrochemical evolution mechanism of river water and groundwater was executed in an arid and semi-arid endorheic watershed located in the eastern edge of Qaidam Basin, northwest China, by analyzing major ions and strontium isotopic compositions with the combination of hydrogeochemical methods, PMF model and Pearson correlation analysis. From upstream to downstream, the major ions, 87Sr/86Sr values and hydrochemical types of river water and groundwater show spatial variations. Major ions and 87Sr/86Sr analysis reveal that the hydrochmical compositions of river water and groundwater are primarily attributed to silicate weathering, carbonate weathering, evaporite weathering, and agricultural activity. The contribution of four factors affecting the hydrochemical evolution show obvious spatial variations along the flow path. The hydrochemical compositions of river water from the upstream to downstream are mainly contributed by carbonate and silicate weathering as well as weak evaporite weathering (<25%), which are affected by agricultural activity with a great contribution (>25%) in the middle and lower reaches. The contribution to the hydrochemical compositions of groundwater is relatively small (<25%) for carbonate, silicate and evaporite weathering, but great (>25%) for agricultural activity. This study provides implications for understanding the formation and evolution of water and better watershed water management in that typical endorheic watershed basin and even at larger scales.

A decision-making framework to maximise the evolutionary potential of populations - Genetic and genomic insights from the common midwife toad (Alytes obstetricans) at its range limits

Anthropogenic habitat modification and climate change are fundamental drivers of biodiversity declines, reducing the evolutionary potential of species, particularly at their distributional limits. Supportive breeding or reintroductions of individuals are often made to replenish declining populations, sometimes informed by genetic analysis. However, most approaches utilised (i.e. single locus markers) do not have the resolution to account for local adaptation to environmental conditions, a crucial aspect to consider when selecting donor and recipient populations. Here, we incorporate genetic (microsatellite) and genome-wide SNP (ddRAD-seq) markers, accounting for both neutral and putative adaptive genetic diversity, to inform the conservation management of the threatened common midwife toad, Alytes obstetricans at the northern and eastern edges of its range in Europe. We find geographically structured populations (n = 4), weak genetic differentiation and fairly consistent levels of genetic diversity across localities (observed heterozygosity and allelic richness). Categorising individuals based on putatively adaptive regions of the genome showed that the majority of localities are not strongly locally adapted. However, several localities present high numbers of private alleles in tandem with local adaptation to warmer conditions and rough topography. Combining genetic diversity and local adaptations with estimates of migration rates, we develop a decision-making framework for selecting donor and recipient populations which maximises the geographic dispersal of neutral and putatively adaptive genetic diversity. Our framework is generally applicable to any species, but especially to amphibians, so armed with this information, conservationists may avoid the reintroduction of unsuitable/maladapted individuals to new sites and increase the evolutionary potential of populations within species.

Suspended particulate matter in the Gulf of Oman: Spatial variations in concentration, bulk composition, and particulate metals controlled by physical and biogeochemical processes

The present work aims to assess the biogeochemical and physical sources of variation in the spatial distribution of suspended particulate matter (SPM), its major biotic and abiotic components, particulate metals, and the Redfield (N:P) stoichiometry of particles in a poorly understood basin of the Gulf of Oman. Particulate samples were collected in February 2022 from the Gulf of Oman aboard the R/V Persian Gulf Explorer, revealing surface SPM concentrations ranging from 140 to 1145 μg/l. The elemental composition of crustal-type elements in the surface offshore region confirmed the input of lithogenic components by aeolian dust from the surrounding deserts. The highest mid-depth SPM levels, with remarkable contribution from CaCO3, were observed at the western shelf edge at 100–300 m depth, supported by the Persian Gulf outflow. Conversely, mid-depth maxima with elevated concentrations of terrigenous elements were observed in the eastern edge, emanating from sediment resuspension and lateral transport under eddy-topography interaction. Organic matter is the most important phase, followed by biogenic silica from the basin-wide winter bloom of diatoms. While signs of CaCO3 dissolution are evident at depths >500 m, the oxidative precipitation of Mn (II) in the upper boundary of the oxygen minimum zone leads to the appearance of perceptible maxima in the vertical profile of particulate MnO2. Seasonal variations in the organic N:P ratio, from summer to winter, at the western station were linked to shifts in phytoplankton assemblage structure, transitioning from cyanobacteria dominance in summer to chain-forming diatoms in winter. The particulate pool of biologically important trace metals was dominated by a non-crustal fraction with enrichment factor followed a descending order: Cd > Mo > Pb > Zn > Ni in surface offshore samples. Metal/P ratios comparison with some previous data from the open ocean SPM and lab cultures of phytoplankton reveals that the Zn/P ratio is significantly exceeded in cultured communities, whereas the Cd/P ratio reflected the consistent demand in the Gulf of Oman compared to reported lab culture requirements.

The last of their kind: Is the genus Scutiger (Anura: Megophryidae) a relict element of the paleo-Transhimalaya biota?

The orographic evolution of the Himalaya-Tibet Mountain system continues to be a subject of controversy, leading to considerable uncertainty regarding the environment and surface elevation of the Tibetan Plateau during the Cenozoic era. As many geoscientific (but not paleontological) studies suggest, elevations close to modern heights exist in vast areas of Tibet since at least the late Paleogene, implicating the presence of large-scale alpine environments for more than 30 million years. To explore a recently proposed alternative model that assumes a warm temperate environment across paleo-Tibet, we carried out a phylogeographic survey using genomic analyses of samples covering the range of endemic lazy toads (Scutiger) across the Himalaya-Tibet orogen. We identified two main clades, with several, geographically distinct subclades. The long temporal gap between the stem and crown age of Scutiger may suggest high extinction rates. Diversification within the crown group, depending on the calibration, occurred either from the Mid-Miocene or Late-Miocene and continued until the Holocene. The present-day Himalayan Scutiger fauna could have evolved from lineages that existed on the southern edges of the paleo-Tibetan area (the Transhimalaya = Gangdese Shan), while extant species living on the eastern edge of the Plateau originated probably from the eastern edges of northern parts of the ancestral Tibetan area (Hoh Xil, Tanggula Shan). Based on the Mid-Miocene divergence time estimation and ancestral area reconstruction, we propose that uplift-associated aridification of a warm temperate Miocene-Tibet, coupled with high extirpation rates of ancestral populations, and species range shifts along drainage systems and epigenetic transverse valleys of the rising mountains, is a plausible scenario explaining the phylogenetic structure of Scutiger. This hypothesis aligns with the fossil record but conflicts with geoscientific concepts of high elevated Tibetan Plateau since the late Paleogene. Considering a Late-Miocene/Pliocene divergence time, an alternative scenario of dispersal from SE Asia into the East, Central, and West Himalaya cannot be excluded, although essential evolutionary and biogeographic aspects remain unresolved within this model.

Soil Cadmium Prediction and Health Risk Assessment of an Oasis on the Eastern Edge of the Tarim Basin Based on Feature Optimization and Machine Learning

Soil heavy metal pollution poses a serious threat to food security, human health, and soil ecosystems. Based on 644 soil samples collected from a typical oasis located at the eastern margin of the Tarim Basin, a series of models, namely, multiple linear regression （LR）, neural network （BP）, random forest （RF）, support vector machine （SVM）, and radial basis function （RBF）, were built to predict the soil heavy metal content. The optimal prediction result was obtained and utilized to analyze the spatial distribution features of heavy metal contamination and relevant health risks. The outcomes demonstrated that： ① The average Cd content in the study area was 0.14 mg·kg-1, which was 1.17 times the soil background value of Xinjiang, making it the primary factor of soil heavy metal contamination in the area. Additionally, the carcinogenicity risk coefficients of Cd for both adults and children were less than 10-4, indicating that there were no significant long-term health risks for humans in the area. ② The estimation accuracies of the five inversion models were compared, and the validation set of the RF model had an R2 value of 0.763 7, which was the highest among the five models. Additionally, the RMSE, MAE, and MBE of the RF model were the smallest among the five models. Therefore, the predicted values of the RF model were most consistent with the measured values of the soil Cd content. The predicted map of soil Cd distribution derived from the RF model coincided best with the interpolation map. ③ The RF model outperformed the other four models in predicting health risks associated with the soil Cd element for both adults and children, resulting in better prediction results. Comparatively, the predicted values of the LR model in the validation set varied greatly, leading to unreliable results. It was demonstrated that the RF was the best model for predicting soil Cd content and evaluating health risks in the study area, considering its superior generalization capability and anti-overfitting ability.

Absenting as a Repertoire of Action

This article draws on fieldwork in the West Bank (2007–2017) to understand how dispossession and ruination are not only spatialized, but engaged and remade. It examines experiences of a settler frontier in Faqu'a, a Palestinian village. People there have a visual vantage point onto the majority of the village lands, which have been expropriated by Israel. Following a demolition by Israel, Faqu'ans have transformed this frontier site from a place for home-building, first into a garbage dump and then, most recently, into a garden. Faqu'ans’ shifting engagements with this site reveal that edgeness, which seems to characterize this location, is not a naturally occurring status. Edges are made. Faqu'ans periodically adjust their proximity to Faqu'a's eastern edge. By examining different people's engagements with one site over a long duration, what the article calls “absenting” comes into view as a primary means by which people adjust proximity to an edge. Proximity can be temporal, spatial, and affective. Absenting is a particularly useful technique under conditions of extreme duress, such as those arising out of life on a frontier that seeks one's disappearance.

Spatial distribution pattern of mustelids in the eastern edge of the Qinghai-Tibet Plateau.

Evolutionary theory predicts that the species of an evolutionarily successful taxon would not overlap in spatial distribution. To test the prediction, we document our research on the spatial associations of mustelids, an evolutionarily successful group of order Carnivore, using infrared camera trap data on species distribution collected from the national nature reserves (NNRs) of Liancheng, Wolong, Tangjiahe and Heizhugou in China in 2017-2021. Data showed seven mustelid species occurring in the study area, including Arctonyx collaris, Meles leucurus, Martes foina, Martes flavigula, Mustela altaica, Mustela nivalis and Mustela sibirica. Following Ricklef's definition of biological community, we identified five networks of species associations. The mustelids occurred in the networks. Species from the same genus, such as M. foina and M. flavigula, stayed in different networks to avoid competition owing to similar feeding habits or habitat preferences. Species with different feeding habits or habitat preferences either occurred in different networks, such as M. altaica and M. flavigula, or coexisted in the same networks but avoided direct spatial associations, such as M. foina and A. collaris. Asymmetrical associations were found between different genera, such as M. foina and M. altaica, or between different subfamilies, such as M. flavigula and A. collaris. These associations may be attributed to interspecific killing or seed dispersal. However, these associations accounted for only a small proportion and would not impact the species diversity of Mustelidae. It is thus concluded that the prediction is supported by our research findings and that spatial avoidance may be the biogeographic strategy of maintaining the species diversity of the family. We also found that the well protection of the mustelids may benefit the overall biodiversity conservation in Heizhugou, an NNR that has experienced severe deforestation.