Influence Of Geographic Distance Research Articles

The influence of geographical distance on the decay of beetle community similarity: Native habitat and agricultural monocultures

The influence of geographical distance on the decay of beetle community similarity: Native habitat and agricultural monocultures

Biodiversity patterns of the coral reef cryptobiota around the Arabian Peninsula

The Arabian Peninsula accounts for approximately 6% of the world’s coral reefs. Some thrive in extreme environments of temperature and salinity. Using 51 Autonomous Reef Monitoring Structure (ARMS), a standardized non-destructive monitoring device, we investigated the spatial patterns of coral reef cryptobenthic diversity in four ecoregions around the Arabian Peninsula and analyzed how geographical and/or environmental drivers shape those patterns. The mitochondrial cytochrome c oxidase subunit I (COI) gene was used to identify Amplicon Sequence Variants and assign taxonomy of the cryptobenthic organisms collected from the sessile and mobile fractions of each ARMS. Cryptobenthic communities sampled from the two ecoregions in the Red Sea showed to be more diverse than those inhabiting the Arabian (Persian) Gulf and the Gulf of Oman. Geographic distance revealed a stronger relationship with beta diversity in the Mantel partial correlation than environmental distance. However, the two mobile fractions (106–500 µm and 500–2000 µm) also had a significant correlation between environmental distance and beta diversity. In our study, dispersal limitations explained the beta diversity patterns in the selected reefs, supporting the neutral theory of ecology. Still, increasing differences in environmental variables (environmental filtering) also had an effect on the distribution patterns of assemblages inhabiting reefs within short geographic distances. The influence of geographical distance in the cryptofauna assemblages makes these relevant, yet usually ignored, communities in reef functioning vulnerable to large scale coastal development and should be considered in ecosystem management of such projects.

Stochastic processes contribute to arbuscular mycorrhizal fungal community assembly in paddy soils along middle and lower Yangtze River

Arbuscular mycorrhizal fungi (AMF) are extensively distributed in environment, and have key effects on regulating soil structure, nutrient cycles, crop productivity, and ecological processes in agricultural ecosystems. However, the biogeographic patterns and underlying ecological processes shaping AMF community assembly remain unclear. The present study examined AMF community composition and diversity in paddy soils along middle and lower reaches of the Yangtze River, and the driving factors and processes of AMF community assembly were assessed based on MiSeq sequencing. The results showed that soil pH, total N and Olsen-P, and soil organic matter (SOM) levels affected AMF community diversity. In addition, there were 4 orders, 8 families along with 8 genera within our study area, where Glomus was the most dominant genus. Moreover, AMF community composition was under the influence of geographic distance and soil characteristics such as pH, SOM, N and P contents, and enzyme activities. However, the contribution of deterministic processes was less than stochastic processes by the null model analysis, suggesting that stochastic processes was the dominant ecological processes shifting AMF community assembly in paddy soils along middle and lower reaches of the Yangtze River. The results sheds more lights on patterns as well as mechanisms driving the assembly of AMF communities within the agricultural ecosystems.

Assessing the Impact of Geographical Distribution and Genetic Diversity on Metabolic Profiles of a Medicinal Plant, Embelia ribes Burm. f.

The extensive use of Embelia ribes Burm. f. (Embelia) in tribal medicine proclaimed global attention as a promising candidate in complementary and alternative medicine. The knowledge of chemical blends is a prerequisite for the selection of raw materials for herbal medicine formulations; however, the influence of geographical distance and genetic diversity on the metabolome of Embelia fruits is unknown. Therefore, we collected Embelia fruits from four locations across the Western Ghats of India and analyzed the metabolic profile and genotypic diversity of Embelia fruits by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and inter simple sequence repeats (ISSR), respectively. LC-MS/MS analysis yielded 583 compounds; however, the trimmed data resulted in 149 compounds. Further, MS/MS analysis identified 36 compounds, among which we reported 30 compounds for the first time from Embelia. These compounds belong to 11 compound classes that suggest location-specific chemical blends of Embelia fruits. Multivariate analysis showed 94% compound diversity across the accessions. ISSR analysis suggests 95% polymorphism across the accessions. A significant positive correlation (80%) between metabolomics and genotypic data matrices validates the genotype's influence in tuning Embelia's metabolic profiles. We conclude that the chemical profiles of Embelia are location-specific, which can be explored for the selection of herbal trade sustainably.

The influence of geographic distance on life-history traits of the carob moth, Ectomyelois ceratoniae (Zeller) (Lepidoptera: Pyralidae)

The influence of geographic distance on life-history traits of the carob moth, Ectomyelois ceratoniae (Zeller) (Lepidoptera: Pyralidae)

Regional Prediction of Ozone and Fine Particulate Matter Using Diffusion Convolutional Recurrent Neural Network.

Accurate air quality forecasts can provide data-driven supports for governmental departments to control air pollution and further protect the health of residents. However, existing air quality forecasting models mainly focus on site-specific time series forecasts at a local level, and rarely consider the spatiotemporal relationships among regional monitoring stations. As a novelty, we construct a diffusion convolutional recurrent neural network (DCRNN) model that fully considers the influence of geographic distance and dominant wind direction on the regional variations in air quality through different combinations of directed and undirected graphs. The hourly fine particulate matter (PM2.5) and ozone data from 123 air quality monitoring stations in the Yangtze River Delta, China are used to evaluate the performance of the DCRNN model in the regional prediction of PM2.5 and ozone concentrations. Results show that the proposed DCRNN model outperforms the baseline models in prediction accuracy. Compared with the undirected graph model, the directed graph model considering the effects of wind direction performs better in 24 h predictions of pollutant concentrations. In addition, more accurate forecasts of both PM2.5 and ozone are found at a regional level where monitoring stations are distributed densely rather than sparsely. Therefore, the proposed model can assist environmental researchers to further improve the technologies of air quality forecasts and could also serve as tools for environmental policymakers to implement pollution control measures.

Does geographic distance benefit or harm cooperative NPD creativity? A contingency model

Existing research widely assumes that geographic distance between partners exerts a negative influence on cooperative outcomes. However, empirical evidence yields contradictory results. To reconcile the current inconsistencies, this study builds on the relational view to develop a conceptual model proposing that geographic distance has a curvilinear relationship with NPD creativity, which is moderated by technical‐level and relational‐level governance mechanisms. The results of hierarchical regressions on a sample of 209 Chinese manufacturing firms show that geographic distance of a firm’s cooperative relationship has a U‐shaped influence on NPD creativity, which is moderated by high levels of IT usage, trust, and shared goals. These findings help to explain the conflicting views on the influence of geographic distance on NPD creativity by demonstrating a curvilinear influence of distance and providing a nuanced understanding of the contingent roles of technical and relational factors as collaborative governance mechanisms affecting the influence of distance. This study contributes to a better understanding of how and under what conditions distance between cooperating firms can confer specific benefits to innovation.

Influence of geographic distance and environmental factors on beta diversity of plants in the Alxa gobi region in northern China

Influence of geographic distance and environmental factors on beta diversity of plants in the Alxa gobi region in northern China

Evaluating the correlation between area, environmental heterogeneity, and species richness using terrestrial isopods (Oniscidea) from the Pontine Islands (West Mediterranean)

Area and environmental heterogeneity influence species richness in islands. Whether area or environmental heterogeneity is more relevant in determining species richness is a central issue in island biogeography. Several models have been proposed, addressing the issue, and they can be reconducted to three main hypotheses developed to explain the species-area relationship: (1) the area-per se hypothesis (known also as the extinction-colonisation equilibrium), (2) the random placement (passive sampling), and the (3) environmental heterogeneity (habitat diversity). In this paper, considering also the possible influence of geographic distance on island species richness, we explore the correlation between area, environmental heterogeneity, and species richness by using faunistic data of Oniscidea inhabiting the Pontine Islands, a group of five small volcanic islands and several islets in the Tyrrhenian Sea, located about 60 km from the Italian mainland. We found that the colonisation of large Pontine Islands may occur via processes independent of geographic distance which could instead be an important factor at a much smaller scale. Such processes may be driven by a combination of anthropogenic influences and natural events. Even in very small-size island systems, environmental heterogeneity mostly contributes to species richness. Environmental heterogeneity could influence the taxocenosis structure and, ultimately, the number of species of Oniscidea via direct and indirect effects, these last mediated by area which may or may not have a direct effect on species richness.

Influence of Geographic Distance on the Floristic Composition of the Miombo Savannah in Unango, Northern Mozambique

Geographic distance results in population decline, influencing species richness, diversity and distribution. The aim of this research was to evaluate the influence of geography on the floristic composition in the Miombo Savannah in Unango the northern part Mozambique. The studied area was 1.8ha, where 20 sample units of 30m * 30m were established using systematic sampling with a distance of 20m and individuals with DBH ≥ 5 cm were measured. The description of species composition and distribution was evaluated using the Importance Value Index (IVI), diversity by the Shannon Index, and the influence of geographical distance on floristic similarity by the Mantel test. In the floristic survey a total of 999 individuals were sampled, belonging to 34 species distributed in 19 families, the Shannon index was 2.6 and in terms of number of species, the Fabaceae family was the most representative in the study area. The species with the highest importance index values in the study area were <i>Brachystegia spiciformis, Brachystegia boehmii, Uapaca kirkiana, Uapaca nitida, Julbernardia globiflora </i>and<i> Salix mucronata</i>. The Mantel test was not significant, showing that the geographical distance does not influence the floristic similarity within the forest formation on a local scale, other factors may have an influence on the similarity between areas such as climate, topography and soils.

Research on Spatial Pattern and Spatial Effect of Marine Science and Technology Innovation Efficiency in China's Coastal Provinces

Chen, Z. and Ma, L., 2020. Research on spatial pattern and spatial effect of marine science and technology innovation efficiency in china's coastal provinces. In: Bai, X. and Zhou, H. (eds.), Advances in Water Resources, Environmental Protection, and Sustainable Development. Journal of Coastal Research, Special Issue No. 115, pp. 42-45. Coconut Creek (Florida), ISSN 0749-0208.The intensity of interaction between China's marine economy and marine science and technology is not symmetrical and there are regional differences. The development of marine economy promotes the progress of marine science and technology. Under the strategic background of “marine power”, marine economy plays an increasingly important role in the national economy. Ecological efficiency takes into account the ecological and economic benefits of economic activities. It requires that the intensity of environmental impact and resource utilization be adapted to the level of the earth's carrying capacity. It is a concentrated expression of the goal of sustainable development. The spatial spillover degree of energy ecological efficiency in a certain area is stronger than that of error impact in the adjacent area. There are positive spatial correlation and spatial agglomeration phenomena in marine economic efficiency of coastal areas. The spatial correlation patterns of different areas have no obvious difference. There is obvious spatial spillover effect under the influence of geographical distance. Therefore, improving the efficiency of marine science and technology innovation is of great significance for accelerating the construction of a powerful marine country and a powerful scientific and technological country.

Geographic distance, venture capital and technological performance: Evidence from Chinese enterprises

Venture capital (VC) plays an increasingly important role in advancing the technological innovation of enterprises. A growing body of evidence suggests that VC influences the technological performance of enterprises. No known empirical studies have focused on the relationships between geographic distance and the enterprise's technological performance. This study explores whether and how the geographic distance between VC institutions and enterprises influences the enterprise's technological performance from the perspective of the VC's equity backgrounds (governmental, private, and foreign) and investment strategies (independent and joint). The findings and conclusions are as follows: (1) The geographic distance between VC institutions and enterprises has a significantly nonlinear effect on the technological performance of the VC-backed enterprise, and they are negatively correlated when the geographic distance is less than the specified threshold. (2) The influence of geographic distance on the enterprise's technological performance varies with the VC's equity backgrounds. Geographic distance has a more significant impact on the technological performance of governmental VC- and private VC-backed enterprise compared with foreign VC-backed enterprise. (3) For different investment strategies, geographic distance also has a distinct influence on the enterprise's technological performance. When compared with joint VC, the impact of independent VC on the enterprise's technological performance is more influenced by geographic distance.

The Information Effect of Securities Analysts’ Hometown Network Capital

Securities analysts are the backbone of transmitting capital market information and influencing resource allocation. However, the uncertainty in the development of China’s capital market and the lagging of public governance mechanisms have led the company to rely on relational contracts formed by long-term transactions. Due to each transaction of a relational contract has its own particularity, it must be embedded within the network of relationships to obtain information between the parties, in order to evaluate the company’s operating activities and value. Therefore, this paper explores the impact of social capital formed by analysts embedded in the company’s regional relationship network (herein referred to as “hometown network capital”) on the accuracy of analyst forecasts.Specifically, based on the research report released by 6970 analyst teams in China’s capital market from 2006 to 2016, this paper finds that: (1) Analysts are more accurate in predicting the profits of the listed companies where their household registration is located, with an average error of 3% lower than that of other analysts; (2) In the area where the social relationship network is more complex and social capital is more important, analysts’ hometown network capital has a greater comparative information advantage; (3) Research reports released by analysts with hometown network capital have produced stronger short-term and long-term market reactions. In addition, this paper finds that the information advantage of analysts’ hometown network capital is reflected not only in the acquisition of private information, but also in the interpretation of public information. At the same time, analysts are more likely to be invited to participate in the research activities of hometown listed companies.The research contributions of this paper are at least as follows: Firstly, it enriches the relevant research on the social relationship network of securities analysts. Different from the direct social relations between analysts and executives of listed companies, the essence of “hometown network capital” of analysts concerned in this paper is a kind of regional social capital of analysts, whose scope includes direct social relations and indirect social relations, thus expanding the research field of analysts’ social relations. Secondly, it supplements the relevant literature about the influence of geographic distance on information transmission mechanism. By comparing the differences between social network distance and geographic distance in information acquisition, this paper provides a new research dimension for understanding the influence of distance on information transmission. Finally, because the transaction behavior and content of the company under the relational transaction mode are dependent on the relationship network of the transaction subject, it is difficult for the analysts as an information intermediary to be independent of the company’s relationship network. With the arrival of the sci-tech innovation board and the registration system, the capital market operation system with “information disclosure as the core” needs to be established urgently.

Does the geographic proximity effect on knowledge spillovers vary across research fields?

Policy makers are interested in the influence of geographic distance on knowledge flows, however these can be expected to vary across research fields. The effects of geographic distance on flows are analyzed by means of citations to scientific literature. The field of observation consists of the 2010-2012 Italian publications and relevant citations up to the close of 2017. The geographic proximity effect is analyzed at national, continental, and intercontinental level in 244 fields, and results as evident at national level and in some cases at continental level, but not at intercontinental level. For flows between Italian municipalities, citations decrease with distance in all fields. At continental level, four fields are identified having knowledge flows that grow with distance; at intercontinental level, this occurs in 26 fields. The influence of distance is more limited in the fields of Humanities and Social sciences, much more significant in the Sciences, mainly in the Natural sciences.

Point-of-Interest Recommendation Based on User Contextual Behavior Semantics

By suggesting new visiting places, point-of-interest (POI) recommendation not only assists users to find their preferred places, but also helps businesses to attract potential customers. Recent studies have proposed many approaches to the POI recommendation. However, the data sparsity and complexity of user check-in behavior still pose big challenges to accurate personalized POI recommendation. To tackle these problems, in this paper, we propose a POI recommendation model named HeteGeoRankRec based on user contextual behavior semantics. First, we employ the meta-path of heterogeneous information network (HIN) to represent the complex semantic relationship among users and POIs. Second, we introduce different context constraints (such as time and weather) into the meta-path, to reveal the fine-grained user behavioral features. Afterwards, we propose a weighted matrix factorization model which considers the influence of geographical distance through the user–POI semantic correlativity matrices generated by multiple meta-paths. Finally, we present a fusion method based on learning to rank, which unifies the recommendation results of different meta-paths as the final user preference. The experiments on the real data collected from Foursquare demonstrate that HeteGeoRankRec has the better performance than the state-of-the-art baselines.

Corporate Investment under Time-Space Compression: Evidence from High-Speed Railway Coverage

The influence of geographical distance on the decision-making behaviors of economic entities is an interesting topic in new economic geography. To investigate the impact of high-speed railway coverage on firms, with high-speed railway coverage in China as a quasi-natural experiment and a different-in-different (DID) regression, the relation between the staggered coverage of high-speed railways and corporate investment was empirically explored using the data of stations of the Chinese high-speed railways and the listed firms from 2009-2017. Grouping tests were conducted according to corporate operational efficiency and financing constraints. In addition, whether the investment of non-state-owned enterprises(non-SOEs) and labor-intensive firms improved due to high-speed railways coverage was analyzed. Results corroborate that the investment in listed firms in cities covered by high-speed railways increases more significantly compared with cities that are not covered. Hence, high-speed railway coverage promoted capital factor liquidity, mitigated financing constraints, and increased corporate investment. Moreover, high-speed railway coverage is more likely to optimize the investment of the groups of firms that have higher asset liquidity, lower financing constraints, intensive labor, or private ownership. The conclusion provides critical insights for the decision-making behaviors of high-speed railway construction and constitutes theoretical basis for the promotion effect of transportation infrastructure construction on corporate investment. DOI: http://dx.doi.org/10.5755/j01.ee.30.2.22786

Molecular phylogeny of Paraonidae (Annelida)

A molecular phylogeny of the family Paraonidae was reconstructed on the basis of 16S rDNA, COI and 18S rDNA sequences obtained from 66 individuals belonging to 38 nominal species and subspecies. In agreement with previous findings, Paraonidae represent a monophyletic group, closely related to Sternaspidae. The topology obtained by the Bayesian and Maximum Likelihood analyses on the combined dataset was not consistent with the traditional view on Paraonidae evolution, nor with a recent cladistic analysis. According to our results, Paraonidae are divided in five clades. The earliest branching clade (Clade I) included five species of the genera Cirrophorus and Paradoneis, whereas the remaining species of these genera were included in the Clade II. The genus Levinsenia is monophyletic and represents the sister group of a highly supported clade including some morphologically homogeneous species previously assigned to the genus Aricidea, which is here described as Blakeia n. gen. The remaining species of Aricidea clustered in a clade that included Paraonis as well. Paraonis can be interpreted as a pedomorphic form of Aricidea, accounting for the strong morphological divergence between the two genera. For priority rules, Aricidea should be considered a junior synonym of Paraonis. None of the subgenera traditionally recognised within Aricidea were monophyletic; in addition, the shallow molecular divergence identified among species, in particular for 18S rDNA sequences, suggests that the adaptive radiation of the genus Aricidea is relatively recent.Phylogenetic relationships suggested that the median antenna is an ancestral character, which has been independently lost several times, though a long, cirriform antenna only occurs in the genus Aricidea. The ancestral number of pre-branchial chaetigers is most likely three, even though arrangements with a higher number of chaetigers have been probably achieved at least twice independently. Notopodial modified chaetae appear to be a plesiomorphy of Paraonidae and they have been lost subsequently, whereas neuropodial modified chaetae have been acquired at least thrice independently through the evolutionary history of the family.Paraonidae show a strikingly high occurrence of cryptic and pseudocryptic species; results of the present work suggest that environmental features play a crucial role in the diversification of this family, whereas the influence of geographical distance appears less pronounced. Lastly, despite their importance in deep-water environments, Paraonidae probably are a primarily shallow-water family, that radiated in the deep sea secondarily.

Corporate Investment under Time-Space Compression: Evidence from High-Speed Railway Coverage

The influence of geographical distance on the decision-making behaviors of economic entities is an interesting topic in new economic geography. To investigate the impact of high-speed railway coverage on firms, we considered high-speed railway coverage in China as a quasi-natural experiment, empirically explored the relation between the staggered coverage of high-speed railways and corporate investment using the data of the stations of Chinese high-speed railways and listed firms from 2009 to 2017and DID regression. Furthermore, grouping tests were conducted according to corporate operational efficiency and financing constraints. In addition, whether the investment of non-SOEs and labor-intensive firms improved due to high-speed railway coverage was analyzed. Results corroborate that the investment in listed firms in cities covered by high-speed railways increases more significantly compared with cities that are not covered. Hence, high-speed railway coverage promoted capital factor liquidity, mitigated financing constraints, and increased corporate investment. Moreover, high-speed railway coverage is more likely to optimize the investment of the groups of firms that have higher asset liquidity, lower financing constraints, intensive labor, or private ownership.The conclusion provides critical insights for the decision-making behaviors of high-speed railway construction and constitutes theoretical basis for the promotion effect of transportation infrastructure construction on corporate investment.

The effect of slope aspect on the phylogenetic structure of arbuscular mycorrhizal fungal communities in an alpine ecosystem

Slope aspect not only modifies microclimate and soil-forming processes, but also significantly influences biogeographical patterns of species and multiple ecosystem functions across terrestrial landscapes. However, the effect of slope aspect on arbuscular mycorrhizal (AM) fungi, a group of functionally important root-associated microorganisms, remains poorly understood. In this study, we investigated AM fungal communities in an alpine ecosystem on a northwest-facing slope (NS) and a southeast-facing slope (SS) along a steep environmental gradient. Ecological processes structuring the fungal communities were inferred according to phylogenetic patterns and species abundance distributions. Thirty-two distinct AM fungal virtual taxa (VTs) were identified, predominantly belonging to the genus Glomus. The change of slope aspect from SS to NS recorded a significant decline in AM fungal richness, resulting in a marked loss of Glomus VTs and the dominance of Rhizophagus. Moreover, both taxonomic and phylogenetic composition of AM fungal communities significantly varied between the two slope aspects, this being largely driven by niche partitioning based on microclimate, soil pH and plant species composition. The influence of geographical distance was negligible. AM fungal communities were phylogenetically clustered on SS and random on NS, suggesting that the central process structuring communities shifted from a niche-dominated filter to the combination of competitive exclusion and a niche filter. Similarly, AM fungal species abundance distribution showed the best fit with the Lognormal model on SS and the Zipf-Mandelbrot model on NS, indicating that community dynamics on both slopes were also in accordance with niche-based mechanisms.

Bird diversity along a gradient of fragmented habitats of the Cerrado.

Understanding the factors that affect biodiversity is of central interest to ecology, and essential to species conservation and ecosystems management. We sampled bird communities in 17 forest fragments in the Cerrado biome, the Central-West region of Brazil. We aimed to know the communities structure pattern and the influence of geographical distance and environmental variables on them, along a gradient of fragmented habitats at both local and landscape scales. Eight structural variables of the fragments served as an environmental distance measurement at the local scale while five metrics served as an environmental distance measurement at the landscape scale. Species presence-absence data were used to calculate the dissimilarity index. Beta diversity was calculated using three indices (βsim, βnes and βsor), representing the spatial species turnover, nestedness and total beta diversity, respectively. Spatial species turnover was the predominant pattern in the structure of the communities. Variations in beta diversity were explained only by the environmental variables of the landscape with spatial configuration being more important than the composition. This fact indicates that, in Cerrado of Goiás avian communities structure, deterministic ecological processes associated to differences in species responses to landscape fragmentation are more important than stochastic processes driven by species dispersal.