Complex Ecological Environment Research Articles

Morphological characters and molecular data reveal ten new forest macrofungi species from Hebei Province, North China

ABSTRACT China has a complex and diverse forest ecological environment, which breeds abundant forest macrofungi, including some edible, medicinal, and poisonous species. During the investigations of macrofungi in the Saihanba National Nature Reserve, North China, we collected abundant specimens of Agaricales and Polyporales within the Agaricomycetes. Based on the morphological characters and molecular evidence of DNA sequences including the internal transcribed spacer (ITS) regions, the large subunit of nuclear ribosomal RNA gene (nLSU), the small subunit of mitochondrial rRNA gene (mtSSU), the small subunit of nuclear ribosomal RNA gene (nuSSU), the largest subunit of RNA polymerase II (RPB1), the second largest subunit of RNA polymerase II gene (RPB2), the β-tubulin gene (TUB), and the translation elongation factor 1-α gene (TEF1), this study identifies ten species of Agaricales and Polyporales new to science, viz. Cyanosporus subpopuli, Gelatinofungus betulina, Lycoperdon pseudoperlatum, Macrocystidia hebeiensis, Mycena subbrunnea, M. subpura, M. variispora, M. violocea-ardesiaca, Picipes griseus, and Pleuroflammula hebeiensis. Detailed morphological descriptions, fruiting bodies, and microscopic structure diagrams of these ten novel species are provided.

A Novel Approach for Simultaneous Localization and Dense Mapping Based on Binocular Vision in Forest Ecological Environment

The three-dimensional reconstruction of forest ecological environment by low-altitude remote sensing photography from Unmanned Aerial Vehicles (UAVs) provides a powerful basis for the fine surveying of forest resources and forest management. A stereo vision system, D-SLAM, is proposed to realize simultaneous localization and dense mapping for UAVs in complex forest ecological environments. The system takes binocular images as input and 3D dense maps as target outputs, while the 3D sparse maps and the camera poses can be obtained. The tracking thread utilizes temporal clue to match sparse map points for zero-drift localization. The relative motion amount and data association between frames are used as constraints for new keyframes selection, and the binocular image spatial clue compensation strategy is proposed to increase the robustness of the algorithm tracking. The dense mapping thread uses Linear Attention Network (LANet) to predict reliable disparity maps in ill-posed regions, which are transformed to depth maps for constructing dense point cloud maps. Evaluations of three datasets, EuRoC, KITTI and Forest, show that the proposed system can run at 30 ordinary frames and 3 keyframes per second with Forest, with a high localization accuracy of several centimeters for Root Mean Squared Absolute Trajectory Error (RMS ATE) on EuRoC and a Relative Root Mean Squared Error (RMSE) with two average values of 0.64 and 0.2 for trel and Rrel with KITTI, outperforming most mainstream models in terms of tracking accuracy and robustness. Moreover, the advantage of dense mapping compensates for the shortcomings of sparse mapping in most Smultaneous Localization and Mapping (SLAM) systems and the proposed system meets the requirements of real-time localization and dense mapping in the complex ecological environment of forests.

Spatial-temporal variations of forest and grassland phenology in the Yellow River Basin during 2000-2018.

The study of vegetation phenology is of great significance for understanding global climate change. The Yellow River basin has a wide spatial range and a complex ecological environment. The phenological characteristics of forest and grassland need further clarification. Based on the MODIS-EVI data from 2000 to 2018, we extracted the phenology of forest and grassland in the Yellow River basin using piecewise logistic and double logistic phenological models with the corresponding curvature change extremum method and derivative method, respectively. The temporal and spatial variations of phenological parameters were analyzed. The start of growing season (SOS) was at 90-165 day of year (DOY), and gradually delayed from southeast to northwest. The increase of 100 m elevation delayed SOS 0.94 d, and the SOS of forest was earlier than that of grassland. The end of growing season (EOS) was at 270-315 DOY, which delayed from west to southeast. For every 100 m increase in altitude, the EOS advanced 0.63 d, with EOS of forest being later than that of grassland. The length of growing season (LOS) was 110-230 d, which shortened gradually from southeast to northwest. The LOS of forest was larger than that of grassland. During the study, SOS showed an advance trend from 2000 to 2018 with a rate of 4.1 d·(10 a)-1, and the proportion of spatial advance area was 73.2%. There was an obvious advance in the central part of the basin. EOS generally showed a significant postponement trend with a rate of 2.3 d·(10 a)-1, and the proportion of spatially delayed area was 63.4%, the phenological advance and delay of forest was less stronger than that of grassland. LOS showed a significant prolongation trend with a rate of 6.4 d·(10 a)-1, and the proportion of spatial extension was 71.8%. The piecewise Logistic and double Logistic phenological models and the corresponding curvature extremum method and derivative method were suitable for the extraction of natural vegetation in the Yellow River Basin. The overall LOS of forest and grassland showed a prolonging trend, which was shortened with the increases of altitude. The LOS of forest was longer than that of grassland in the study area.

Spaetzle responds to the process of Neoseiulus barkeri resistance to Beauveria bassiana infection

The application of Beauveria bassiana is proved to be a feasible biological control measure against pest insects and mites (e.g. Liu et al. 2018; Al Khoury et al. 2020). But the complex and variable ecological environment can affect the efficiency of B. bassiana. Due to the powerful search and spread ability of predatory mites, they were proposed to carry and spread pathogenic microbial spores to places that are difficult to be covered by conventional spray methods (Chen et al. 2020; Hao et al. 2021). This biocontrol strategy of combining fungi with predator mites is predicted to play a synergistic role in pest control. Therefore, the tolerance of predator mites to B. bassiana and the underlying mechanism have been the subject of extensive research and remained to be explored further. The infection of insects by B. bassiana can induce insect innate immune response. Spaetzle protein (Spz), as an important ligand of insect Toll pathway, has been demonstrated to play an important role in insect innate immune defense system. 

Changes in near-surface permafrost temperature and active layer thickness in Northeast China in 1961–2020 based on GIPL model

Characteristics of active layer processes depend on the conditions of the ground surface, coupled water-heat balance, soil hydrology, and soil properties under frozen and thawed states at shallow depths. Mean annual temperature at the bottom of the active layer (MATBAL) and active layer thickness (ALT) are important metrics in studying the features of active layer processes and the thermal stability of permafrost. Affected by the changing climate, permafrost regions in Northeast China have undergone remarkable changes in the past 30 years, many of which are still ongoing. In Northeast China, however, model studies on examining hydrothermal dynamics and on changes in frozen ground have faced serious challenges, including a complex ecological environment and rugged terrains. In this study, the Geophysical Institute Permafrost Lab (GIPL) model was used to map temporal and spatial variations in MATBAL and ALT in Northeast China, where discontinuous, island, and sporadic permafrost coexists with seasonal frost. Using the parameters of ground surface temperature (GST) and soil properties as input, we applied the GIPL model to analyze the distributive characteristics of near-surface permafrost in Northeast China. The results indicate a sharply shrinking permafrost area from 5.49 × 105 to 2.29 × 105 km2 but rapidly rising rates of 0.17–0.83 °C/decade in MATBAL in Northeast China during the period from 1961 to 2020. Under a persistently warming climate, accelerating permafrost degradation will inevitably affect the hydrological environment, boreal ecosystem, soil biology, and engineering infrastructure. This work fills a gap in the distribution of MATBAL and ALT in Northeast China.

Ecological quality assessment and monitoring using a time-series remote sensing-based ecological index (ts-RSEI)

ABSTRACT Ecological quality assessment is fundamental to revealing changes in ecological environments before the development of effective ecological conservation policies. The complex ecological environment can be assessed more reliably when multiple remote sensing indices are integrated, such as in the use of the prevalent Remote Sensing-based Ecological Index (RSEI). However, for effective ecological quality assessment, the requirement of acquisition time consistency for images has become an outstanding issue for broadening the application of the RSEI. In this study, we adjusted the RSEI to the Continuous Change Detection and Classification (CCDC) algorithm that predicts synthetic images instead of real images. Based on this algorithm, we mapped time-series RSEI (ts-RSEI), which provide comparable results for tracing the dynamics of ecological quality at any time. Our major findings are as follows: (1) The RSEI is very sensitive to the timespan of the image acquisition dates, with the Mean Absolute Difference (MAD) of 0.111 (19.2%) when the interval between dates exceeds one month. (2) The ts-RSEI from synthetic images is comparable to the RSEI from real images, with the MAD of 0.075 (10.5%), which is superior to that of two real images with the timespan of half-a-month. (3) For Hangzhou, the ecological quality was maintained for almost the past 35 years (the ts-RSEI changed from 0.679 to 0.705). However, special attention should be paid to the spatial polarization between natural (“better”) and human-dominated (“worse”) environments. The high temporal consistency and the capability of any- time mapping of the ts-RSEI are expected to be of value to policy makers and authorities in implementing effective ecological conservation measures.

Sponge City Policy and Sustainable City Development: The Case of Shenzhen

The massive construction of buildings has changed the city’s aquatic ecological environment. The aquatic ecological condition of the city has been deteriorated with serious water issues. To coordinate various departments to jointly build the sponge city and improve the water environment, the Shenzhen government formulated the policy note on “Interim Measures for the Construction Management of Shenzhen Sponge City”. This article discusses the impact of the policy note on Shenzhen’s construction of sponge cities. The result shows that the policy is effective from the perspective of the environment. However, in the face of a complex water ecological environment, there are still some deficiencies in the policy. We therefore put forward policy suggestions for the Shenzhen municipal government to better manage its construction of sponge city in the future.

Ecosystem service value evaluation method in a complex ecological environment: A case study of Gansu Province, China.

The scientific assessment of regional ecosystem service value (ESV) is helpful in developing scientific ecological protection plans and compensation policies. However, an ESV evaluation method that can adapt to the complex and diverse characteristics of the ecological environment has not been established. This study takes Gansu Province in China as an example, fully considering the regional differences in ecosystem service function. Five correction indices for the value equivalent factor per unit area were constructed on a provincial scale, and a regional difference adjustment index for 11 categories of ecosystem services was constructed on a regional scale. In this way, a value evaluation model based on regional differences was established. The results show that in 2015, the total ESV reached 2,239.56 billion yuan in Gansu Province, with ESV gradually increasing from the northeast to the southwest, and the high-value areas of service function being located in Qilian and Longnan Mountains. The forest and grassland ecosystems contributed the most to the ESV. From the perspective of value composition, local climate regulation and biodiversity maintenance functions are the main service functions of Gansu Province. From 2000 to 2015, ESV increased by 3.43 billion yuan in the province. The value of forest and urban ecosystems continued to increase, whereas the value of cultivated land ecosystem continued to decrease. In terms of spatial characteristics of the service value change, the area that experienced value reduction gradually moved from the central part of Gansu Province to the surrounding areas. The evaluation method proposed in this paper provides a relatively comprehensive evaluation scheme for the spatiotemporal dynamic evaluation of ESV in complex ecological environments.

Co-culture: stimulate the metabolic potential and explore the molecular diversity of natural products from microorganisms.

Microbial secondary metabolites have long been considered as potential sources of lead compounds for medicinal use due to their rich chemical diversity and extensive biological activities. However, many biosynthetic gene clusters remain silent under traditional laboratory culture conditions, resulting in repeated isolation of a large number of known compounds. The co-culture strategy simulates the complex ecological environment of microbial life by using an ecology-driven method to activate silent gene clusters of microorganisms and tap their metabolic potential to obtain novel bioactive secondary metabolites. In this review, representative studies from 2017 to 2020 on the discovery of novel bioactive natural products from co-cultured microorganisms are summarized. A series of natural products with diverse and novel structures have been discovered successfully by co-culture strategies, including fungus-fungus, fungus-bacterium, and bacterium-bacterium co-culture approaches. These novel compounds exhibited various bioactivities including extensive antimicrobial activities and potential cytotoxic activities, especially when it came to disparate marine-derived species and cross-species of marine strains and terrestrial strains. It could be concluded that co-culture can be an effective strategy to tap the metabolic potential of microorganisms, particularly for marine-derived species, thus providing diverse molecules for the discovery of lead compounds and drug candidates.

A Framework of Resilience Development for Poor Villages after the Wenchuan Earthquake Based on the Principle of “Build Back Better”

Under the current resilience development framework, which is mainly based on urban communities, it is difficult to meet the needs of the vulnerable populations in poor villages. This article aims to explore a specific and operable guidance framework suitable for the resilient development of Chinese poor villages after disasters from the perspective of social equity. The framework will help guide the sustainable development of poor villages after disasters and also provide a reference for the resilience of other similar vulnerable areas. When integrating climate change response and disaster risk management to explore sustainable development in poor villages, the essence is to explore the resilience development framework focused on the construction of resilient communities in poor villages. We take the recovery and reconstruction of poor villages after the Wenchuan earthquake in 2008 as an example. Through the analysis of the effects of post-disaster recovery and reconstruction, we found that although poor communities have made significant achievements since the earthquake, there are still many aspects that need to be improved, including social life systems, economic production systems, and natural ecosystems. Therefore, we comprehensively analyzed the characteristics of poor socio-economic conditions, the complex ecological environment, and the low cultural level of residents in poor villages. Furthermore, this study followed the principle of “Build back better” (BBB) and conducted an in-depth study of the framework for the resilience of poor villages. In terms of risk reduction, it is recommended to improve structural resilience from guarantee of preferential prices and selection of environmentally friendly materials, avoid risk and villagers’ participation in the formulation of general plans, and promote disaster prevention and mitigation capabilities from risk prediction and curriculum development. In terms of community recovery, it is suggested to promote community economics and victims’ livelihoods by promoting industrial transformation and sustainable livelihoods and promote social and psychological health development from social relations and psychological rehabilitation. In terms of efficient implementation, specific improvements include the improvement of public participation systems and the establishment of coordination offices and sound institutional mechanisms, the development of community standards and the introduction of financial support policies, the improvement of laws and regulations, and the improvement of monitoring and evaluation from dynamic monitoring and mass satisfaction surveys. It is important to guide the sustainable development of vulnerable communities by constructing a post-disaster resistant development framework based on BBB principles.

Evaluation of Geological and Ecological Bearing Capacity and Spatial Pattern along Du-Wen Road Based on the Analytic Hierarchy Process (AHP) and the Technique for Order of Preference by Similarity to an Ideal Solution (TOPSIS) Method

As China is a mountainous country, a large quantity of the population has to live in mountainous areas due to limited living space. Most of them cluster along roads in areas with relatively poor traffic conditions. In view of the spatial-temporal change of complex geological and ecological environment along the roads in the mountains, this paper takes the Dujiangyan- Wenchuan (Du-Wen) Road as the research object, and puts forward a method to evaluate the bearing capacity of regional geological and ecological environment based on the evaluation of quality and spatial coupling of bearing capacity. For the needs of the current research, a total number of 20 indicators from three aspects of geological, ecological, and social attributes were selected to carry out the assessment. Based on the GIS platform and evaluation index system, the weight of each evaluation index factor is determined by Analytic Hierarchy Process (AHP). The comprehensive quality of bearing capacity is calculated by the Technique for Order of Preference by Similarity to an Ideal Solution (TOPSIS) algorithm through weighted superposition, which comes to result in the evaluation of geological, ecological, and social environment. Afterward, the bearing capacity of the study area is classified, combining the results of hot spot analysis. The study shows that the spatial distribution of geological, ecological, and socio-economic bearing capacity in this area is highly aggregated, with 31.12% of the area to be classified as suitable construction area, 31.98% as backup reserve area, and 36.79% as unsuitable construction area. The studied triangle area, composed of Yingxiu Town, Xuankou Town, and Dujiangyan City, presents a large area of a high-valued aggregation area, with comprehensive high quality bearing capacity and spatial aggregation, which is better for planning and construction.

The delineation of urban growth boundaries in complex ecological environment areas by using cellular automata and a dual-environmental evaluation

Urban growth boundaries are an efficient tool for protecting non-urban land uses from being dominated by urban sprawl and can promote sustainable urban development. Previous studies have explored the use of a cellular automata simulation and its visualization products in delimiting future UGBs. However, existing CA-UGB delineation models lack a transcendental component for ecological evaluation and are difficult to apply to areas with complex ecological environments or heterogeneous resource endowments. Therefore, this paper introduces an innovative model by coupling the dual-environmental evaluation and the Future Land-use Simulation CA model for delimiting future UGBs. To prioritize ecological protection, some intermediate products of the DEE are processed as pivotal components in the CA simulations. Strict urban simulation constraints are also applied in the FLUS model to meet the DEE regulations and prioritize ecological protection. This model was implemented to plan future UGBs in Chungking, China. After quantifying and comparing the proposed UGB scheme with other UGB delineations of Chungking by using various landscape metrics, the DEE-UGBs show a stronger ability to manage urban patches via aggregation with the simultaneous reconciliation of contradictions among land uses.

A conceptual framework for establishing the index system of ecological environment evaluation–A case study of the upper Hanjiang River, China

Abstract Index system is a vital tool for evaluating the ecological environment. In this study, we present a version of ecological hierarchy network (EHN) called “ecological-factor conceptual framework” for the organization of index system. This conceptual framework divides the complex ecological environment into four subsystems that all have explicit definitions or ranges, namely climate factors, soil-terrain factors, biology resource factors and human factors. Our framework makes the selection of indices more explicit and based on science, as well as more representative. Using the ecological-factor conceptual framework, we established an evaluation index system for the upper Hanjiang River in Shaanxi province, China. The index system contained fourteen indicators, such as average annual precipitation, elevation, biological abundance index, net primary productivity (NPP), highway net density and industrial wastewater emission. The ecological environment was comprehensively evaluated using spatial principal component analysis (SPCA). In addition, we used the matrix of principal components to quantitatively analyze the driving forces that affected the ecological environment. The results show that Hanzhong Downtown and Chenggu County had poor ecological environment with ecological environment index (EEI) values of −0.1459 and 0.3506, respectively. Areas that were rated as moderate, high and very high accounted for 86.07% of the study area. We found that human factors were the most important factors driving the deterioration of the ecological environment in the study area.

Comprehensive analysis of the mitochondrial DNA diversity in Chinese cattle.

Complete mitochondrial DNA D-loop sequences of 1105 individuals were used toassess the diversity of maternal lineages of cattle populations in China. In total, 250 taurine and 88 zebu haplotypes were identified. Five main haplogroups-T1a, T2, T3, T4 and T5-were identified in Bos taurus, whereas Bos indicus harbored two haplogroups-I1 and I2. Our results suggest that the distribution of T1a in Asia was concentrated mainly in the northeast region (northeast China, Korea and Japan); haplogroups T2, T3 and T4 were predominant in Chinese cattle; and T5 was sporadically detected in Mongolian and Pingwu cattle. In contrast to the widespread presence of I1, I2 was distributed only in southwestern China (Yunnan-Guizhou Plateau and the Tibet Autonomous Region) and Xinjiang Uygur Autonomous Region. This is the first time that all five taurine haplogroups and two zebu haplogroups have been found in Mongolian cattle. In addition, eight individuals in Tibetancattle carried the Bos grunniens mtDNA type. The high mtDNA diversity (H=0.904±0.008) and the weak genetic structure among the 57 Chinese cattle breeds/populations are consistent with their complex historical background, migration route and ecological environment.

The complete mitochondrial DNA genome sequence of a terrestrial grasshopper, Curvipennis wixiensis (Acrididae: Podismini)

Curvipennis wixiensis is a rare species of terrestrial grasshopper with limited distribution in a few untraversed mesophorbium regions of the northwest Yunnan Province. This species has specific morphological characteristics, and the local complex ecological environment is considered to play an important role in the evolution of the species. Characterization of the sources of C. wixiensis is useful for local biodiversity conservation and ecological preservation. In this study, we determined the complete mitochondrial DNA genome of C. wixiensis. This circular genome (15,528 bp in length) contains 13 protein-coding genes (PCGs), 2 rRNA genes, 22 tRNA genes and one control region. All PCGs in C. wixiensis are distributed on the H-strand, except for the ND6 gene and eight tRNA genes, which are encoded on the L-strand. We expect that the complete mitochondrial DNA genome of C. wixiensis will provide valuable molecular data for species identification, conservation genetics research and evolutionary studies.

Quantifying PM2.5 capture capability of greening trees based on leaf factors analyzing.

As PM2.5 affect human health, it is important to target tree planting in the role of reducing air pollution concentrations. PM2.5 capture capability of greening trees is associated with leaf morphology, while quantitative research is scanty. In this paper, the PM2.5 capture capability of 25 species in Beijing and Chongqing were examined by a chamber device. Groove proportion, leaf hair, stomatal density, and stomata size were selected as indexes of leaf morphology. Results showed that groove proportion and stomata size significantly relate to PM2.5 capture quantity, while no significantly positive correlations were found for leaf hairs and stomatal density. Broadleaf species are conducive to PM2.5 capture for their rich leaf morphology and have an edge over coniferous in PM2.5 capture per leaf area. However, coniferous had a larger PM2.5 capture capability per tree due to the advantage of a large leaf area. Significant difference existed between the species in Beijing and Chongqing due to the different leaf morphology. Urban greening trees are diverse and the structures are complicated. Complex ecological environment may lead to different morphology characteristics. Climate and pollution conditions should be considered when greening.

Land Cover Change Characteristics of North-South Transect in Northeast Asia from 2001 to 2012

Abstract: Northeast Asia is an area with relative concentrations of resources, a complex ecological environment pattern, and a marked human—land contrast relationship. This area has significance for analyzing land cover patterns and variations for regional sustainable development among the trans-boundary areas of China, Russia, and Mongolia. In this paper, the transect analysis research tool and transfer matrix method are used to capture the regional land cover change characteristics by using Moderate Resolution Imaging Spectroradiometer(MODIS) datasets recorded from 2001 to 2012. The spatial distribution results show that forests have increased dramatically, cropland increased marginally, and grassland and shrubs decreased totally. The inter-annual variation, results show a steady and slowly increasing trend for grassland and shrubs, dramatic fluctuation features with an increasing trend for forest land, and zigzag wave changing characteristic for cropland. The total land use dynamic degree (TLUDD)was st...

Dynamic monitoring of wetland cover changes using time-series remote sensing imagery

Time-series remote sensing data, such as Moderate Resolution Imaging Spectroradiometer (MODIS) data hold considerable promise for investigating long-term dynamics of land use/cover change (LUCC), given their significant advantages of frequent temporal coverage and free cost. However, because of the complex ecological environment of wetlands, the applicability of these data for studying temporal dynamics of wetland-related land-cover types is limited. This is especially so for the Poyang Lake, China's largest freshwater lake, which has active seasonal and inter-annual dynamics. The primary objective of this study is to investigate the suitability of MODIS 250-m maximum value composite (MVC) vegetation indexes (VIs) for dynamics monitoring of the Poyang Lake. We applied a time-series 16-day MODIS NDVI from 2000 to 2012 and developed a method to classify wetland cover types based on timing of inundation. We combined techniques of applying iterative self-organizing data analysis (ISODATA) with varying numbers of clusters and a transformed divergence (TD) statistic, to implement annual classification of smoothed time-series NDVI. In addition, we propose a decision tree based on features derived from NDVI profiles, to characterize phenological differences among clusters. Supported by randomly generated validation samples from TM images and daily water level records, we obtained a satisfactory accuracy assessment report. Classification results showed various change patterns for four dominant land cover types. Water area showed a non-significant declining trend with average annual change rate 33.25km2, indicating a drier Poyang lake, and emergent vegetation area had weak change over the past 13years. Areas of submerged vegetation and mudflat expanded, with significant average annual change rate 23.51km2 for the former. The results suggest that MODIS' 250-m spatial resolution is appropriate and the classification method based on timing of inundation is useful for mapping general land cover patterns of Poyang Lake.

Analysis of kinetoplast cytochrome b gene of 16 Leishmania isolates from different foci of China: different species of Leishmania in China and their phylogenetic inference.

BackgroundLeishmania species belong to the family Trypanosomatidae and cause leishmaniasis, a geographically widespread disease that infects humans and other vertebrates. This disease remains endemic in China. Due to the large geographic area and complex ecological environment, the taxonomic position and phylogenetic relationship of Chinese Leishmania isolates remain uncertain. A recent internal transcribed spacer 1 and cytochrome oxidase II phylogeny of Chinese Leishmania isolates has challenged some aspects of their traditional taxonomy as well as cladistics hypotheses of their phylogeny. The current study was designed to provide further disease background and sequence analysis.MethodsWe systematically analyzed 50 cytochrome b (cyt b) gene sequences of 19 isolates (16 from China, 3 from other countries) sequenced after polymerase chain reaction (PCR) using a special primer for cyt b as well as 31 sequences downloaded from GenBank. After alignment, the data were analyzed using the maximum parsimony, Bayesian and netwok methods.ResultsSequences of six haplotypes representing 10 Chinese isolates formed a monophyletic group and clustered with Leishmania tarentolae. The isolates GS1, GS7, XJ771 of this study from China clustered with other isolates of Leishmania donovani complex. The isolate JS1 was a sister to Leishmania tropica, which represented an L. tropica complex instead of clustering with L. donovani complex or with the other 10 Chinese isolates. The isolates KXG-2 and GS-GER20 formed a monophyletic group with Leishmania turanica from central Asia. In the different phylogenetic trees, all of the Chinese isolates occurred in at least four groups regardless of geographic distribution.ConclusionsThe undescribed Leishmania species of China, which are clearly causative agents of canine leishmaniasis and human visceral leishmaniasis and are related to Sauroleishmania, may have evolved from a common ancestral parasite that came from the Americas and may have split off earlier than the other old world Leishmania. Our results also suggest the following: the isolates GS7, GS1 and XJ771 occur as part of the L. donovani complex; the JS1 isolate is L. tropica; and the isolate GS-GER20 identified as Leishmania gerbilli is close to KXG-2 which is L. turanica.

A probabilistic cellular automata approach for predator–prey interactions of arrowtooth flounder (Atheresthes stomias) and walleye pollock (Theragra chalcogramma) in the eastern Bering Sea

We developed a hybrid cellular automata (CA) modelling approach to explore the dynamics of a key predator–prey interaction in a marine system; our study is motivated by the quest for better understanding of the scale and heterogeneity-related effects on the arrowtooth flounder (Atheresthes stomias) and walleye pollock (Theragra chalcogramma) dynamics during the summer feeding season in the eastern Bering Sea (EBS), but can be readily extended to other systems. The spatially explicit and probabilistic CA model incorporates individual behaviours and strategies and local interactions among species, as well as spatial and temporal heterogeneity due to geographical and (or) environmental changes in the physical environment. The model is hybridized, with an individual-based model (IBM) approach for increasing its capacity and continuum and for balancing between computational efficiency and model validity, which makes it suitable for simulating predator–prey dynamics in a large, complex ecological environment. We focus on the functional and aggregative responses of predators to prey density at different spatial scales, the effects of individual behaviours, and the impacts of systematic heterogeneity. Simulations from the model with suitable parameter values share qualitatively similar features found in field observations, e.g., local aggregations around hydrographical features. Spatial heterogeneity is an important aspect of whether local-scale functional and aggregative responses reflect those operating over large, or global, scales.