Distribution Limit Research Articles

New data on Dysdera Latreille, 1804 and Harpactea Bristowe, 1939 (Araneae: Dysderidae) of the Caucasus, with new species and records.

In this paper, we provide new taxonomic and faunistic data on the dysderid spider genera Dysdera Latreille, 1804 and Harpactea Bristowe, 1939 based on material collected in the Caucasus region. We identified a total of seventeen species, of which D. atabekia sp. n. (; Goychay and Ismayilli districts, Azerbaijan), H. abasgiana sp. n. (; Republic of Abkhazia, Georgia), and H. dunini sp. n. (; Zagatala district, Azerbaijan) are described as new to science and their distributions are mapped. Furthermore, three new records are provided: D. daghestanica Dunin, 1991 from Krasnodar Krai, D. concinna L. Koch, 1878 from Iran, and D. mazini Dunin, 1991 from Azerbaijan. By examining the type series of Harpactea caucasia (Kulczyski, 1895), we found that at least a part of Dunins records of this species refer to H. abasgiana sp. n., and his figures of this species in fact refer to an undescribed species. Brief notes are provided on the northernmost distribution limits of Dysderidae.

Tree canopy area-dependent changes in soil properties: a comparative study in the southern limit of boreal forest distribution

The forest distribution in relation to mountain slope position and the relationships between forest canopy area and soil physical and chemical properties in Mongolia attract the attention of scientists. In this study, we aimed to determine (1) how the slope aspect affects the forest soil physical and chemical properties, (2) how the soil variables correlate with projected canopy area. For comparative study, we established a total of 18 (20 × 25 m2 sized) sample plots in upper forest edge (UFE), upper slope of the forest (USF), lower slope of the forest (LSF), lower forest edge (LFE), sparse forest (SF), and degraded forest area (DFA) stand types with three replications. We measured the tree height, diameter and crown projection area of each growing tree in the sample plots, and collected soil samples for further soil physical and chemical analyses in the laboratory. Our results showed a high variation in growing stock (p < 0.0001), stand density and projected canopy area (p < 0.0001) in relation to mountain slope position and land-use management. We found that the slight changes in stand canopy area projection cause a high variation in soil physical and chemical properties. Among studied stand types higher means of soil temperature and bulk density and lower moisture content were observed on SF and DFA stand types. Contrary, relatively higher content of soil moisture and nutrient elements were recorded in USF, LSF, LFE. We conclude that tree canopy area becomes key determinant factor that positively influences forest soil moisture and fertility by increasing organic matter content in Mongolia.

RANGE EXTENSION OF &lt;i&gt;Synbranchus marmoratus&lt;/i&gt; (SYNBRANCHIDAE) TOWARDS ARGENTINA’S CENTRAL ANDES

This work provides a new record that extends the western limit of the geographic distribution of Synbranchus marmoratus towards the Central Andes of Argentina, in the Department of Calingasta, Province of San Juan. In addition, an update of the geographical distribution map of the species in the country is provided based on this record and a complete literature review. We collected a specimen of this species on 12 September 2016 during an ichthyofaunal survey of high Andean rivers. This record corresponds to the westernmost distribution in the country. This finding is interesting since this species is considered an indicator of the ichthyofauna of the Biogeographic Provinces Greats Rivers and Pampean, while the ichthyofauna of the study area of this new record belongs to the Andean Cuyo Province.

Negative interaction effect of heat and drought stress at the warm end of species distribution

Geographic range limits of species are often a reflection of their ecological niche limits. In many organisms, important niche limits that coincide with distribution limits are warm and warm-dry conditions. We investigated the effects of heat and drought, as they can occur at the warm end of distribution. In a greenhouse experiment, we raised North American Arabidopsis lyrata from the centre of its distribution as well as from low- and high-latitude limits under average and extreme conditions. We assessed plant growth and development, as well as leaf and root functional traits, and tested for a decline in performance and selection acting on growth, leaf, and root traits. Drought and heat, when applied alone, lowered plant performance, while combined stress caused synergistically negative effects. Plants from high latitudes did not survive under combined stress, whereas plants originating from central and low latitudes had low to moderate survival, indicating divergent adaptation. Traits positively associated with survival under drought, with or without heat, were delayed and slowed growth, though plastic responses in these traits were generally antagonistic to the direction of selection. In line, higher tolerance of stress in southern populations did not involve aspects of growth but rather a higher root-to-shoot ratio and thinner leaves. In conclusion, combined heat and drought, as can occur at southern range edges and presumably more so under global change, seriously impede the long-term persistence of A. lyrata, even though they impose selection and populations may adapt, though under likely interference by considerable maladaptive plasticity.

Inference for Projection-Based Wasserstein Distances on Finite Spaces

The Wasserstein distance is a distance between two probability distributions and has recently gained increasing popularity in statistics and machine learning, owing to its attractive properties. One important approach to extending this distance is using low-dimensional projections of distributions to avoid a high computational cost and the curse of dimensionality in empirical estimation, such as the sliced Wasserstein or max-sliced Wasserstein distances. Despite their practical success in machine learning tasks, the availability of statistical inferences for projection-based Wasserstein distances is limited owing to the lack of distributional limit results. In this paper, we consider distances defined by integrating or maximizing Wasserstein distances between low-dimensional projections of two probability distributions. Then we derive limit distributions regarding these distances when the two distributions are supported on finite points. We also propose a bootstrap procedure to estimate quantiles of limit distributions from data. This facilitates asymptotically exact interval estimation and hypothesis testing for these distances. Our theoretical results are based on the arguments of Sommerfeld and Munk (2018) for deriving distributional limits regarding the original Wasserstein distance on finite spaces and the theory of sensitivity analysis in nonlinear programming. Finally, we conduct numerical experiments to illustrate the theoretical results and demonstrate the applicability of our inferential methods to real data analysis.

Prediction of the Breeding and Wintering Ranges of Pomacea canaliculata in China Using Ensemble Models

Pomacea canaliculata is a pest species of freshwater neotropical gastropod that has colonized the coastal regions of southern China since the 1980s and has expanded its range into temperate regions of the Yangtze River Basin. The breeding and overwintering populations of P. canaliculata have increased during its gradual northward expansion over the past 40 years. There is a high likelihood that P. canaliculata can overwinter in areas conducive to breeding due to the impacts of a changing climate. Yet, the potential future changes in the range of P. canaliculata and associated climatic determinants remain unclear. This study examined the relationship between the limits of geographic distribution and key climate variables determining suitability for P. canaliculata breeding and wintering periods using the ensemble species distribution models from the R package BIOMOD2. Future climate suitability and changes were assessed under two representative concentration pathways (RCP 4.5 and RCP 8.5). The predictions indicated that P. canaliculata is most sensitive to monthly minimum temperature and that this species will extend its breeding range towards northern latitudes and will establish increased wintering locations in China. The predictions for both breeding and overwintering populations suggest a northward shift in the most suitable habitat, a reduction of highly suitable areas in the south, and an increase in suitable areas along the center and east of the Yangtze River Basin extending further northwards. Within the context of an overall expansion in P. canaliculata and climate warming, there should be a focus on the center of the Yangtze River Basin in which this species can overwinter for breeding only. Early monitoring and proactive measures to effectively prevent further spread of this species should be prioritized in this region characterized by abundant rice cultivation and fish breeding.

Scaling limit of the cluster size distribution for the random current measure on the complete graph

Scaling limit of the cluster size distribution for the random current measure on the complete graph

The Implications of Geotechnical Properties of Soil in the Development of Gully Erosion in Ukpor, Southeastern Nigeria

Gully erosion is a devastating form of soil degradation threatening environmental sustainability, socio-economic development, and human well-being worldwide. The Southeastern region of Nigeria, particularly Ukpor, is prone to gully erosion, which has resulted in the loss of infrastructure, agricultural land, and human settlements. While various factors contribute to gully erosion, the soil’s geotechnical properties remain an important aspect that has been given limited attention. This study investigates the implications of geotechnical properties of soils in the development of gully erosion in Ukpor. A comprehensive approach was adopted, combining drone-aided geologic field mapping, laboratory tests and spatial analysis. Soil samples were collected from different locations at 0.5 – 1m depth, and laboratory tests (Particle Size Distribution (PSD) and Atterberg Limits) were conducted to determine the soil’s geotechnical properties. The results reveal that the study area is underlain by the Ogwashi-Asaba formation. From the Particle Size Distribution and Atterberg Limit tests, the soils in the area were classified into 3; Group A (coarse-grained clayey sands), Group B (coarse-grained poorly graded to clayey sands) and Group C (poorly-graded coarse-grained sands). The Plasticity Index (PI) of Group A ranges from 13.4 – 18.2 while the Liquid Limit (LL) ranges from 27.8 to 34.9. The PI of Group B ranges from 15.49 to 17.35 while the LL ranges from 30.7 to 35.7, From the results, Group C soils were most affected by gullying. Given the above, the underlying soil strata of Ukpor metropolis could be classified as low plasticity soil, thus, highly susceptible to erosion. The results show a significant correlation between soil geotechnical properties and gully erosion susceptibility. The results have pivotal implications for soil conservation, sustainable land management, and infrastructure development in Ukpor and similar regions. The study recommends soil stabilization techniques and vegetation management strategies to mitigate gully erosion.

Current Vaccine and Efficacy of COVID-19 in Latin America: Challenges and need for updated public health policy

In Latin America, the COVID-19 pandemic, which initially surged and is now a constant presence, has brought about significant health challenges due to disparities and differences in regional responses. Vaccination is not only a necessity but also a responsibility as the primary tool for prevention. However, its implementation has not been consistent across countries, leading to various challenges such as global demand, initial high costs, infrastructure limitations for distribution, public hesitance, and misinformation. Other issues, like vaccine efficacy in immunocompromised patients and the use of different vaccines, were initially questioned but are now regarded as strategies to protect patients. This region, with its unique traditions, also faces several risk factors including vaccine supply shortages, lack of vaccine manufacturing, overcrowded cities, and an increasing migrant population that adds to the vulnerability of the people, challenging countries to strive for equity in prevention strategies. It is important to address individual strategies in communities to increase vaccine uptake as part of public health policy, and collaboration between countries should be encouraged to reach more people. This review will provide information about the COVID-19 vaccines available in the region, their characteristics and composition, their use across countries, and the reported effectiveness in the general population and among those with weakened immune systems.

ОСОБЕННОСТИ ЭКОЛОГО-ГЕОГРАФИЧЕСКОЙ ПРИУРОЧЕННОСТИ РЕДКОГО ВИДА TULIPA BORSZCZOWII REGEL (LILIACEAE) В ПРЕДЕЛАХ КАЗАХСТАНА

The article presents the results of critical review of available herbarium specimens of Tulipa borszc-zowii Regel (Liliaceae) – a rare species listed in the List of Rare and Threatened Plant Species (2006); Red Books: Kazakh SSR (1981), South Kazakhstan (Turkestan) region (2002); Republic of Kazakhstan (2014), Kyzylorda region (2014). The aim of the study was to investigate its current distribution and ecological habitat to identify potential growing sites within the Republic. Specimens of the studied species stored in such major Herbaria as: AA, TASH, MW, LE were reviewed. A total of 147 herbarium specimens were viewed during the study. Also, in the process of work was carried out screening of domestic and foreign sources (including electronic databases) containing information on the places of Tulipa borszczowiigrowth. As a result of the research: the morphological description of the species was supplemented with detailing the range of color gamma of perianth lobes; the northern boundaries of the Kazakh part of the Tulipa borszczowii area were specified, which are simultaneously the northern limits of distribution of the species as a whole and the list of floristic areas of Kazakhstan in which it is fixed was expanded; a map-scheme of the species locations within the Republic was drawn up; The tasks for further research are formulated, in particular, the need for biometric studies and clarification of both the northwestern and northeastern limits of Tulipa borszczowii growth.

Twenty years of population dynamics in European beech-oak forest at their rear range margin anticipate changes in its structure and composition

There is an increasing interest in restoring degraded forests, which occupy half of the forest areas. Among the forms of restoration, passive restoration, which involves the elimination of degrading factors and the free evolution of natural dynamics by applying minimal or no management, is gaining attention. Natural dynamics is difficult to predict due to the influence of multiple interacting factors such as climatic and edaphic conditions, composition and abundance of species, and the successional character of these species. Here, we study the natural dynamics of a mixed forest located in central Spain, which maintained an open forest structure, due to intensive use, until grazing and cutting were banned in the 1960s. The most frequent woody species in this forest are Fagus sylvatica, Quercus petraea, Quercus pyrenaica, Ilex aquifolium, Sorbus aucuparia, Sorbus aria and Prunus avium, with contrasting shade and drought tolerance. These species are common in temperate European deciduous forest and are found here near their southern distribution limit, except for Q. pyrenaica. In order to analyze forest dynamics and composition, three inventories were carried out in 1994, 2005 and 2015. Our results show that, despite the Mediterranean influence, the natural dynamics of this forest has been mainly determined by different levels of shade tolerance. After the abandonment of grazing and cutting, Q. pyrenaica expanded rapidly due to its lower shade tolerance, whereas after canopy closure and forest densification, shade-tolerant species gained ground, particularly F. sylvatica, despite its lower drought and late-frost tolerance. If the current dynamics continue, F. sylvatica will overtake the rest of the species, which will be relegated to sites with shallow soils and steep slopes. Simultaneously, all the multi-centennial beech trees, which are undergoing a rapid mortality and decline process, will disappear.

Massive barnacle recruitment on the Gulf of St. Lawrence coast of Nova Scotia (Canada) in 2024 linked to increased sea surface temperature.

With the ongoing climate and oceanographic change, an increasing number of studies are reporting dramatic population losses caused by thermal extremes in intertidal habitats. Under moderate warming, however, populations can fare better in places where species normally experienced suboptimal temperatures. This article reports the massive recruitment of the barnacle Semibalanus balanoides on the Gulf of St. Lawrence coast of Nova Scotia (Canada) in 2024. As recruits appear mostly during May in this region, coastal sea surface temperature (SST) in April is critical for the ecological performance of larvae, as they are pelagic and live in the water column for weeks before intertidal settlement. Thus, a study that spanned 12 years (2005 to 2016) on this coast found that annual barnacle recruitment was positively correlated to April SST. In April 2024, coastal SST was 116% higher than for the same month averaged over those 12 years (4.1 vs. 1.9 °C). This SST spike was followed by an elevated recruitment that was 111% higher than the average for those 12 years (1,278 vs. 607 recruits dm-2). Overall for the studied years, the amount of variation in annual barnacle recruitment statistically explained by April SST was 51%. While the southern distribution limit of S. balanoides has moved northwards in recent decades due to lethal warming, our results support the notion of improving reproductive success with seawater warming on colder northern shores.

Arithmetic properties of multiplicative integer-valued perturbed random walks

Let $({\xi _{1}},{\eta _{1}})$, $({\xi _{2}},{\eta _{2}}),\dots $ be independent identically distributed ${\mathbb{N}^{2}}$-valued random vectors with arbitrarily dependent components. The sequence ${({\Theta _{k}})_{k\in \mathbb{N}}}$ defined by ${\Theta _{k}}={\Pi _{k-1}}\cdot {\eta _{k}}$, where ${\Pi _{0}}=1$ and ${\Pi _{k}}={\xi _{1}}\cdot \dots \cdot {\xi _{k}}$ for $k\in \mathbb{N}$, is called a multiplicative perturbed random walk. Arithmetic properties of the random sets $\{{\Pi _{1}},{\Pi _{2}},\dots ,{\Pi _{k}}\}\subset \mathbb{N}$ and $\{{\Theta _{1}},{\Theta _{2}},\dots ,{\Theta _{k}}\}\subset \mathbb{N}$, $k\in \mathbb{N}$, are studied. In particular, distributional limit theorems for their prime counts and for the least common multiple are derived.

Thinning reduces late-spring frost impact on stem radial growth in a beech forest stand

Resistance and resilience to multiple stresses depend on competition among trees, thus they can be improved by means of silvicultural practices reducing stand density. However, we often ignore whether thinning is an appropriate practice to increase the resistance and resilience to late-spring frosts. These climatic events can damage tree species, especially when leaf emergence is advanced by warmer springs. Here, we compared the effect of a late-spring frost on crown damage and stem radial growth in beech trees (Fagus sylvatica) from areas thinned and not thinned. The study area is a mixed forest of F. sylvatica, Quercus petraea and Q. pyrenaica, and is located in central Spain, near the southern limit of beech distribution. The proportion of trees damaged by frost was not significantly different in thinned vs non-thinned areas. However, severely damaged trees in non-thinned areas showed higher growth reductions and a longer legacy effect than severely damaged trees in thinned plots. Severely damaged trees were those with earlier leaf and stem growth phenology in the frost year. These trees, compared to slightly damaged trees, delayed growth cessation and had a longer growth period in the frost year, and the year afterwards in non-thinned areas. Growth recovery was size-dependent in non-thinned areas, in which bigger trees recovered growth faster. The positive effect of thinning in attenuating frost impact on growth and accelerating growth recovery adds up to other beneficial effects of thinning for stress tolerance. Similar results could occur in other deciduous species highly sensitive to spring temperatures, which are likely to increase with global warming.

The intra-annual rhythm of Pinus sylvestris growth-climate responses under a warming climate at its southern distribution limits

Warming climate has posed a pressing threat on boreal forests and an improved understanding of the intra-annual pattern of climatic influences on the tree growth can help interpret the response of boreal forest to climate change. Here, we systematically examined the growth-climate relationship, cambium phenology, and xylem cell dynamics of Pinus sylvestris (PS) to disentangle its intra-annual growth rhythm to external drivers and internal physiological process at its southern distribution limits across Eurasia. We showed the intra-annual rhythm of PS to temperature and precipitation is anti-phase and synchronous at its southern limits. Temperature had both promoting and inhibiting effects on PS growth over growing season where the growth-temperature response gradually changed from positive in winter-early spring to negative in late spring-summer, and then returned to positive in autumn. Precipitation enhanced PS growth in late spring-summer. Temperature dominated the intra-annual growth-climate response rhythm, and the response shifted to negative when temperature reached 13.72 °C in spring-summer and shifted to positive when temperature reached 17.41 °C in summer-autumn in Shenyang, respectively. A high water demand for the rapid earlywood cell formation in spring-summer and heat requirement for cambial cell division in summer-autumn caused the shifts in growth-temperature response, respectively. Climatic warming advances and prolongs the time of summer water availability that limits PS growth at its southern distribution limits and thus warming climate may pose a greater threat to the southern population of PS.

Sexual reproduction of &lt;i&gt;Acropora pruinosa&lt;/i&gt; at its northern distributional limit

Sexual reproduction of &lt;i&gt;Acropora pruinosa&lt;/i&gt; at its northern distributional limit

Impact of Environmental Conditions on Wood Anatomical Traits of Green Alder (Alnus alnobetula) at the Alpine Treeline

Due to land use change, green alder (Alnus alnobetula), formerly restricted to moist slopes, is now expanding to drier sun-exposed sites at the alpine treeline. The highly productive shrub is forming closed thickets, establishing nitrogen-saturated species poor shrublands. To evaluate wood anatomical adaptations to changing environmental conditions, we analyzed vessel characteristics (mean vessel area, MVA; vessel density, VD; and theoretic conductive area, TCA) and axial parenchyma abundance, as well as their distribution in the annual ring at a moist north-facing and a dry south-facing site at the alpine treeline on Mt. Patscherkofel (Central European Alps, Austria). Results revealed that lower soil water availability and enhanced evaporative demand did not affect MVA while VD and TCA were significantly reduced at the dry south-facing site. This suggests that in green alder, vessel size is a static trait whereas vessel number responds plastic. Limited water availability also triggered a significant increase in axial parenchyma, confirming the important role of xylem parenchyma in water relations. Harsh environmental conditions at the distributional limit of green alder may have affected xylogenesis, leading to a near semi-ring-porous distribution of vessels and an accumulation of parenchyma in the late growing season. We conclude that in a warmer and drier climate, growth limitation and physiological stress may set limits to the distribution of Alnus alnobetula at drought-prone sites in the alpine treeline ecotone.

Cross-database and cross-channel electrocardiogram arrhythmia heartbeat classification based on unsupervised domain adaptation

The classification of electrocardiogram (ECG) plays a crucial role in the development of an automatic cardiovascular diagnostic system. However, the considerable variances in ECG signals between individuals pose a significant challenge. Changes in data distribution limit cross-domain utilization of a model. In this study, we propose a solution to classify ECG in an unlabeled dataset by leveraging knowledge obtained from labeled source domain. We present a domain-adaptive deep network based on cross-domain feature discrepancy optimization. Our method comprises three stages: pre-training, cluster-centroid computing, and adaptation. In pre-training, we employ a Distributionally Robust Optimization (DRO) technique to deal with the vanishing worst-case training loss. To enhance the richness of the features, we concatenate three temporal features with the deep learning features. The cluster computing stage involves computing centroids of distinctly separable clusters for the source using true labels, and for the target using confident predictions. We propose a novel technique for selecting confident predictions in the target domain. In the adaptation stage, we minimize compacting loss within the same cluster, separating loss across different clusters, inter-domain cluster discrepancy loss, and running combined loss to produce a domain-robust model. Experiments conducted in both cross-domain and cross-channel paradigms show the efficacy of the proposed method. Our method achieves superior performance compared to other state-of-the-art approaches in detecting ventricular ectopic beats (V), supraventricular ectopic beats (S), and fusion beats (F). Our method achieves an average improvement of 11.78% in overall accuracy over the non-domain-adaptive baseline method on the three test datasets.

Conservation Genetics of the Only Honeysuckle Azalea (Rhododendron luteum) Population Present in Greece

Honeysuckle azalea (Rhododendron luteum) has only a single population occurrence in Greece, on Lesvos Island of the north-eastern Aegean Sea. The genetic diversity of this population was studied in a population of n = 37 individuals randomly sampled in a transect spanning between the highest and lowest natural altitudinal distribution limits in Mt. Ordymnos, SW Lesvos. A modified DNA extraction and isolation protocol was used to overcome problems of DNA quality due to secondary metabolite activity. Genetic variation was investigated based on molecular Inter Simple Sequence Repeat (ISSR) markers. Results showed the presence of a sufficient amount of genetic diversity for the maintenance of adaptive potential. Genetic diversity was lower but comparable to that of other Rhododendron species sampled from the centre of their natural distribution, despite the relatively small population size, negative anthropogenic pressure and population isolation due to the island environment. Some structuring of genetic diversity was indicated based on a PCoA analysis and the genetic distance dendrogram, while spatial autocorrelation was highly significant. Results point towards the need to assign a protection status to the whole area of the species’ natural distribution on Lesvos Island. Moreover, it is proposed that an in situ Gene Conservation Unit (GCU) be established in the core of this population in Lesvos as part of the Network of the European Forest Genetic Resources Programme, while the establishment of ex situ conservation is also advised.

Environmental and geographic low suitability overlapping of geoduck clams in the Pacific Northeast predicted by Ecological Niche Modeling

The known distribution limits of geoduck clams (genus Panopea) remain geographically separated globally. However, in the northeast Pacific, P. generosa is distributed from Alaska to northern Mexico, but approaches, and likely overlaps, the distribution of P. globosa, which is mainly distributed in the Gulf of California. There is incipient evidence that both populations coexist in the central part of the Baja California Peninsula on the Pacific coast. However, knowledge of the biogeographic distribution and environmental conditions for both species is still developing. To address the hypothesis of coexistence in the same geographic space, we developed distribution area models using ecological niche modeling through the maximum entropy algorithm. The algorithm used presence-only records and environmental layers (predictive variables) such as mean surface temperature, mean salinity, mean depth, temperature range, and primary productivity. The results indicate that both species overlap in a narrow portion of the environmental space (Grinnellian ecological niche), which is reflected in a restricted geographic distribution with conditions of low abiotic suitability. Our results contribute to directing new research in the areas of ecology, biogeography, paleontology, and geoduck clam fisheries management.