Overlap Index Research Articles

Ecological Traits and Intraguild Competition Mediate Spatial and Temporal Overlaps Among Sympatric Mesocarnivores

In terrestrial mammalian carnivore guilds, interspecific competitions (interferences and resource competitions) among sympatric species induce their ecological and behavioral patterns and population dynamics, thereby shaping community structures. Competitive species must partition their ecological niches for sympatry, while the extent of niche overlaps is mediated by either the ecological traits (e.g., body size differences) or environmental features. We aimed to elucidate the patterns of spatial and temporal niche overlaps in mesocarnivore guilds, which are mediated by their ecological traits, regional environments, and anthropogenic disturbances. We investigated the spatial occurrence and diel activities of six mesocarnivore species and estimated their spatial and temporal overlap indices in various landscapes with different anthropogenic disturbances in central Bulgaria. Statistical modeling demonstrated that spatial overlap among mesocarnivores declined when mesocarnivore pairs were within the same family and when large carnivores (particularly wolves, Canis lupus) were present. Furthermore, we found that the extent of their temporal overlaps was associated with taxonomic and body size differences in mesocarnivore pairs as well as their trophic competitions. Our findings indicated that the intensity of interferences among mesocarnivore species was key for the decline of spatial or temporal niche overlap to relax antagonistic interactions.

Diet, feeding, and niche overlap of west coast steenbras (Lithognathus aureti) and silver kob (Argyrosomus inodorus) in the northern Benguela.

In this study, we described and compared the diet, monthly feeding intensity, and condition of west coast steenbras (Lithognathus aureti) and silver kob (Argyrosomus inodorus) caught at a unique habitat in the northern Benguela. Stomach contents of 179 west coast steenbras and 114 silver kob caught from October 2020 to September 2022 were investigated. The peak in feeding intensity of west coast steenbras appeared to be opportunistic during winter and summer periods depending on food availability. The fish condition, however, peaked at the beginning (October) and at the end (April) of the austral summer spawning period, with the hepatosomatic index (HSI) at 1.5% and the condition factor (CF) at 0.022%. Seven prey taxa were found in the diet of west coast steenbras (bivalves, bony fishes, other mollusks, algae, crustaceans, cnidaria, and polychaetas) and six taxa in the diet of silver kob (bivalves, crustaceans, bony fishes, algae, starfish, and zooplankton), indicating generalist feeding behavior in both the species. The bivalves were the most important prey items in the diet of west coast steenbras (95.9% index of relative importance [IRI]). The most important prey items in the diet of silver kob were crustaceans (83.1% IRI) and bony fishes (16.0% IRI). Crustaceans were most important in the diet of small-to-medium-sized silver kob, whereas bony fishes were most important in the diet of larger silver kob(>75 cm), with significant differences of IRI% by size class. Schoener's index of niche overlap indicated a relatively low overall niche overlap (0.11) between west coast steenbras and silver kob. This allows them to coexist as their feeding habits allow them to occupy unique niches in the coastal reef and sandy habitat and reduce competition for resources.

Species behavioral characteristics lead to unique fragmentation threats: The Nubian ibex as a case study

AbstractThe behavioral characteristics of species may result in certain populations being inherently more susceptible to fragmentation. For example, species exhibiting spatial sexual segregation or those constrained to elongated and narrow habitats. We studied the fragmentation threats, spatial dynamics, resource utilization, and movement ecology of a particularly vulnerable species that is both sexually segregated and constrained to elongated and narrow habitat—the north Judean Desert population of Nubian ibex (Capra nubiana). From 2016‒2020 we tracked 48 marked ibex (27 male, 21 female), of which 38 (20 male, 18 female) also had global position system (GPS) collars. Using GPS‐collar and camera‐trap data in zones delineated around perennial water sources (PWSs), we calculated ibex drinking frequencies and individual utilization distributions by season and sex, focusing on their overall (95% isopleth) and core (50% isopleth) home ranges. We quantified joint space use between sexes using a utilization distribution overlap index (UDOI) and ibex daily movements and space use via movement indices. Female groups formed philopatric activity centers that were anchored around PWSs year‐round and arranged in a metapopulation‐like structure, with no female movement detected between them. Conversely, movement of adult males changed seasonally, with the cores of male groups anchored around PWSs only during the dry season, and long‐range movement between female activity centers during the rut. Female groups also spent more time at steeper terrain and higher elevations compared with male groups. Outside the rut, groups of males and groups of females exhibited minimal joint space use (i.e., average dry season UDOI was 0.06). These patterns indicate high sensitivity of this population to intersexual fragmentation by obstacles (physical or virtual). Management strategies to mitigate fragmentation threats for such populations should be sex‐specific and landscape‐oriented.

Assessing weak interaction and threshold effects of the trophic field overlap index on the relationship between species uniqueness and centrality in food webs

Assessing weak interaction and threshold effects of the trophic field overlap index on the relationship between species uniqueness and centrality in food webs

An optimal configuration strategy of multi-chiller system based on overlap analysis and improved GA

For design of the multi-chiller system, the configuration can be optimized that the system is high efficiency when it is operated under frequent load and operation condition in one year. Base on this idea, the paper presents a novel strategy of optimal configuration of multi-chiller system. The high hour-density range of annual load distribution and the high-efficiency region of combination of chillers are presented respectively, and their obtaining methods are developed. The overlap index is defined to evaluate the overlap between the high-efficiency region and high hour-density range, and it is maximized for the proposed optimal configuration strategy. GA is improved and employed for optimization. The proposed optimal configuration strategy is validated in a real multi-chiller system. The results show that the optimal configuration configured by the proposed strategy can improve annual Energy Efficiency Ratio (EER) about 5 % comparing with the original configuration of the real system. The configurations using equivalent strategy and typical non-equivalent strategy are compared, and the results show that both of hourly COP and annual EER of the configuration of the proposed strategy are better than them. 50 random configurations enumerated from chiller candidates are also compared. The results show that the overlap index is strongly correlated to annual EER, and it can be taken as optimization object for optimal configuration. Improved GA is compared with original GA, and the results show that of computation time cost can be reduced more than 60 % by use of Improved GA. The validation results show that the proposed strategy can obtain the optimal configuration of multi-chiller system directly from chiller candidates.

Water Niche Characteristics of Subalpine Shrub in Eastern Qilian Mountains, China

ABSTRACTThe investigation and research of plant niche provide new ideas for understanding the extent of resource utilization by plants and the coexistence relationship among species. Taking the subalpine shrub plants in the eastern Qilian Mountains as the research object, the contribution rate of each potential water source to the shrub plants was estimated using the Bayesian mixed modelling (MixSIAR), and the spatial and temporal characteristics of their water niche were analysed quantitatively using Levins' niche breadth index and Pianka's niche overlap index. The results showed that shrub plants on the semi‐shady slope exhibited larger water niche breadth and overlap compared to those on the semi‐sunny slope, which indicated that shrub plants on the semi‐shady slope had strong adaptability to the water environment, but the competition for water among them was more intense. Furthermore, the water niche breadth and overlap of shrub plants decreased with the promotion of the growth stage, which was related to changes in precipitation and plant physiological characteristics during their growth cycle. Among the studied species, Potentilla fruticosa Linn., Salix oritrepha Schneid., Salix cupularis Rehd. and Rhododendron thymifolium Maxim. had broader water niche breadth in different habitats, indicating superior adaptability to the subalpine environment. Despite that the water niche overlap among shrub plants was high and their competition for water resources was intense, there was no absolute positive correlation between niche breadth and overlap. The research can provide a theoretical reference for the rational allocation of species during vegetation restoration in Qilian Mountain National Park.

Analysis of the Interrelation and Seasonal Variation Characteristics of the Spatial Niche of Dominant Fishery Species-A Case Study of the East China Sea.

The spatial niche has garnered significant attention in ecological research, particularly regarding species distribution patterns. The East China Sea, known for its favorable natural conditions and abundant fishery resources, exhibits diverse spatial distribution patterns among species, shaped by their seasonal physiological needs. This study utilized a habitat suitability index model to explore the spatial distribution patterns of key fishery resources in the East China Sea across four seasons and their interactions. Two methodologies were employed to identify key environmental factors and assess the ecological niche overlap among different species and seasons. Results indicated that the initial method identified water temperature as the critical factor for hairtail, while the subsequent method emphasized water temperature and salinity for hairtail, salinity for small yellow croaker, and water depth for Bombay duck. The main spatial habitat overlap was observed between paired species, likely driven by predator-prey interactions. During summer and autumn, increased overlap among multiple species was primarily influenced by synchronized life cycles. An overlap index formula quantified the seasonal species overlap, showing an increase from spring to winter, reflecting changes in convergent habitat preferences. The peak overlap occurred in winter, driven by overwintering, reduced food competition, and enhanced coexistence potential, while the lowest overlap was noted in spring as overwintering ended and predation and competition intensified.

The Ecological Niches and Interspecific Associations of the Dominant Fishes in the Xiamen Seas, China

Fish are vital in enhancing the stability of marine ecosystems. Therefore, understanding the ecological niches and interspecific correlation characteristics of their dominant species provides a good scientific basis for the protection and management of marine biodiversity. In this study, on the basis of survey data from trawls conducted in the waters off Xiamen in the spring (April) and autumn (November) of 2021, the ecotopes and interspecies connectivity of the dominant fish species were investigated using the relative importance index (IRI), χ2 tests, the association coefficient (AC), and Pearson and Spearman analyses. According to the IRI, there were 23 fish species with higher values, including 15 species in spring and 15 species in autumn. The 15 dominant fish species could be subdivided into wide-, medium-, and narrow-ecotope species, of which there were 2 and 3 wide-ecotope types in spring and autumn. The niche overlap indices exhibited a range of 0.000–0.809 in the spring and 0.000–0.915 in the autumn, showing small differences between the two seasons. The interspecific correlations between the dominant fishes in Xiamen’s waters in spring and autumn were weak, and both showed non-significant positive correlations, indicating that the correlations between the dominant fishes in this sea area are relatively independent. The findings of this investigation provide a fundamental database and theoretical framework for researching the adaptive mechanisms of marine fish in the Xiamen Seas.

Niche of woody plant populations in Picea purpurea community in the upper Taohe River

The niche of plant populations is affected by the environment, species characteristics and anthropogenic disturbance. Picea purpurea, as a major constructive species in the northeastern Qinghai-Tibetan Plateau, had been severely damaged. Although the national project for the protection of natural forests has promoted the recovery of its community, its structure, survival status, development trend, and the factors affecting it are still unclear. We selected P. purpurea communities in Zecha, Dayugou and Yeliguan forest zones at different altitudes and disturbance levels. We analyzed niche characteristics of the woody plants and the relationship between niche and altitude, and disturbance. P. purpurea has absolute advantages as a constructive species, and its population dominance and niche width in the tree layer show a decreasing trend with decreasing altitude, there is niche overlap between all species pairs. In the shrub layer, the dominant species are mostly Caprifoliaceae and Rosaceae besides P. purpurea seedlings, the proportion of species pairs with niche overlap is YLG>ZC>DYG, and all appeared niche divergence and convergence species pairs. In addition, P. purpurea seedlings had niche overlap with most woody species, and this overlap index was the highest. The mean values of the niche overlap index between species in the tree and shrub layers were all YLG>DYG>ZC. The niche overlap index between species in the tree layer was greater than that in the shrub layer in the same forest zones, indicating that the tree layer is more stable than the shrub layer, providing evidence that niche overlap maintains community stability. Regression analyses showed that minimum temperature was the main factor affecting dominance, niche, niche overlap and shrub layer species richness of the P. purpurea population. Disturbance did not significantly affect dominance and niche of P. purpurea seedling populations, but promoted niche differentiation of shrub layer species. We conclude that the P. purpurea community is mainly influenced by altitude and anthropogenic disturbance. Altitude-induced climatic variation fundamentally determines the distinct community composition and population niche. Anthropogenic disturbance has altered habitat heterogeneity and enriched community structure. Furthermore, the P. purpurea populations show a trend towards expansion. Understanding the structure and niche characteristics of P. purpurea communities on different environmental gradients enriches our ideas for implementing vegetation restoration and sustainable forest management in subalpine zones in the context of climate change, and is conducive to improving the conservation capacity of this population or community type.

Intraspecific and interspecific resource partitioning between bumblebee workers and males related to nectar quantity and quality.

Bumblebees are important pollinators for many natural and agricultural systems in temperate regions. Interspecific and intraspecific variation in floral resource preferences have been proposed to influence bumblebee community structure. In particular, sexual dimorphism is a major source of intraspecific niche variation. Although interspecific resource partitioning is well studied, few studies have explored the intraspecific dynamics between workers and males. Here, we report a study on a total of 11528 workers and 2220 males of 14 bumblebee species recorded over 5years in the Hengduan Mountains of Southwest China. We first compared the potential for interspecific and intraspecific competition between workers and males using visitation records and resource partitioning indices (overlap index). We then evaluated the influence of nectar traits on flower preference, including nectar volume and the levels of hexose, sucrose and 10 essential amino acids (EAAs). We found that the niche overlap between intraspecific workers and males was higher than that between different species, and temporal overlap alone did not strongly determine diet overlap. Males of most species preferred flowers with high levels of EAAs and hexose, whereas workers of some species preferred flowers with high nectar volume and sucrose levels. This study suggests that there is floral resource partitioning among bumblebee species, and between workers and males, which may play a key role in alleviating interspecific and intraspecific competition. These findings also provide a useful guide for which kinds of plants might be most valuable for bumblebees, especially the understudied males, in this biodiversity hotspot.

Range dynamics of Anopheles mosquitoes in Africa suggest a significant increase in the malaria transmission risk.

Despite a more than 100-year effort to combat malaria, it remains one of the most malignant infectious diseases globally, especially in Africa. Malaria is transmitted by several Anopheles mosquitoes. However, until now few studies have investigated future range dynamics of major An. mosquitoes in Africa through a unified scheme. Through a unified scheme, we developed 21 species distribution models to predict the range dynamics of 21 major An. species in Africa under future scenarios and also examined their overall range dynamic patterns mainly through suitability overlap index and range overlap index. Although future range dynamics varied substantially among the 21 An. species, we predicted large future range expansions for all 21 An. species, and increases in suitability overlap index were detected in more than 90% of the African continent for all future scenarios. Additionally, we predicted high range overlap index in West Africa, East Africa, South Sudan, Angola, and the Democratic Republic of the Congo under future scenarios. Although the relative impacts of land use, topography and climate variables on the range dynamics depended on species and spatial scale, climate played the strongest roles in the range dynamics of most species. Africa might face an increasing risk of malaria transmissions in the future, and better strategies are required to address this problem. Mitigating climate change and human disturbance of natural ecosystems might be essential to reduce the proliferation of An. species and the risk of malaria transmissions in Africa in the future. Our strategies against their impacts should be species-specific.

Habitat use by a bird community in a Caatinga area: habitat seasonality and overlap

Habitat degradation is one of the main drivers of biodiversity loss, a phenomenon that significantly manifests in the Caatinga domain, where extensive habitat areas undergo modifications. Therefore, understanding how organisms select their habitats becomes crucial for effective conservation management. In this context, the present study aims to analyze habitat use, seasonality, and overlap within a bird community in an area located within the Caatinga domain, specifically at Fazenda Aba. Twelve monthly expeditions were conducted using the point-count method to estimate usage areas, habitat intensity, and overlap during both dry and rainy periods. Usage areas were measured using the Minimum Convex Polygon (MCP 100%) method, while the Kernel 95% estimator was employed to assess habitat intensity. Overlap was calculated using the Utilization Distribution Overlap Index (UDOI). The results revealed comprehensive use of the study area by the bird community, with more pronounced usage intensity in riparian forest environments. Additionally, an increase in usage areas was observed during the rainy period compared to the dry season, reflecting greater overlap during the scarcity season. It is suggested that riparian forest habitats play a fundamental role in maintaining avifauna, especially during droughts, promoting seasonal movements of species that tend to shift to areas with higher resource availability, resulting in convergence of utilized areas.

Dietary habits of fishing cats in a human-dominated wetland in Coastal Thailand

Abstract. Wongson T, Khaewphakdee S, Mongkonsin W, Serieys LEK, Wong W-M, Yindee M, Pattanarangsan R, Suksavate W, Promkuntod P, Klakhaeng C, Sukmasuang R. 2024. Dietary habits of fishing cats in a human-dominated wetland in Coastal Thailand. Biodiversitas 25: 2788-2797. Fishing cats, intimately connected to wetland habitats, face an escalating threat from human activities and environmental change. With its significant findings, this study offers a comprehensive insight into the dietary habits of fishing cats in a human-dominated wetland in coastal Thailand. By examining the scats of 192 fishing cats (Prionailurus viverrinus Bennett 1833) and the remains of 328 prey items, we detailed the fishing cat's diet and assessed its seasonality. Consequently, we identified 16 prey species consumed by fishing cats during the study period. The primary prey was fish, followed by rodents, birds, Indo-Chinese rat snakes (Ptyas korros (Hermann Schlegel 1837)), insects, crabs, and snails. The most crucial prey was the climbing perch (Anabas testudineus Bloch 1792) (n=69), followed by bandicoot rats (Bandicota indica Bechstein, 1800) (n=54), domestic chicken (Gallus gallus Linnaeus 1758) (n=48), and snakehead murrel (Channa striata Bloch 1793) (n=38). The niche breadth index indicated the highest specialization during the summer, while the dietary diversity index was 0.44, 0.52, and 0.38 during the summer, rainy, and winter seasons, respectively. Seasonal variations in dietary composition were not statistically significant. The niche overlap index was 0.95 between the summer and the rainy season, 0.91 between the rainy season and winter, and 0.87 between the summer and winter. These findings, with their direct implications for the conservation of fishing cats, highlight the urgent need for effective land-use management in species preservation.

Distance mapping overlap complexity metric for class-imbalance problems

Data complexity for class-imbalance problems is a hot topic in the field of data mining. Classical data complexity measures use techniques such as kNN, which computes the nearest neighbors of each instance. However, the kNN-based method to obtain the nearest neighbors of all instances is an NP-hard problem, which is not conducive to large-scale data complexity calculations. In order to solve this problem, from the global and local perspectives, four distance map complexity metric methods are proposed, and the complexity values is called the distance map overlap index (DMOI). Firstly, we use Mahalanobis distance or standardized Euclidean distance to calculate the distance of the instance to the center point of the data set, and arrange by the distance value of each instance. Then, according to the sequential label vector, iteratively searches the number of map cut-points for each class. Finally, according to the number of map cut-points of different classes, the DMOI of the data set is calculated. Experiments on 50 class-imbalanced datasets show that the DMOI method outperforms state-of-the-art complexity measures for class-imbalanced problems. Although there is still a gap between DMOI and ONB for rule-based or tree-based classifiers, the use of Pearson correlation coefficient shows that DMOI can effectively approximate ONB, and there is a strong positive correlation between them.

Home range of three turtle species in Central Yucatan. A comparative study

Home range is a fundamental characteristic of an animal natural history. The study of home range provides information on the sites where organisms forage for food, find shelter, or locate mates. Home range size and shape can change throughout the lifespan of an organism, during the year, or across seasons, driven by resource availability and the basic needs for each organism. For freshwater and semi-aquatic turtles, home range is greatly affected by water availability, humidity, and temperature throughout the year, nevertheless demographic factors such age and sex are also important determinants of home range size. In this study we estimated home range and dispersal movements for Kinosternon creaseri, Terrapene yucatana, and Rhinoclemmys areolata in a semi-tropical dry forest in central Yucatán. For a two-year period, turtles were surveyed using hoop traps and visual encounters. Twenty-one individuals (5–8 per species) were equipped with radio transmitters to track them across the landscape. Distances between relocations and home range were compared across species seasons, sex, and interactions of these variables. Monthly average movements were positively correlated with rain in the three species studied. Home range of R. areolata was larger than those of K. creaseri and T. yucatana. Home range of the three studied species were larger during the wet season. Home range overlap index within same species individuals was higher during the rainy than dry season, but overall overlap is low between and within species.

IL-2-free tumor-infiltrating lymphocyte therapy with PD-1 blockade demonstrates potent efficacy in advanced gynecologic cancer

BackgroundTumor-infiltrating lymphocyte (TIL) therapy has been restricted by intensive lymphodepletion and high-dose intravenous interleukin-2 (IL-2) administration. To address these limitations, we conducted preclinical and clinical studies to evaluate the safety, antitumor activity, and pharmacokinetics of an innovative modified regimen in patients with advanced gynecologic cancer.MethodsPatient-derived xenografts (PDX) were established from a local recurrent cervical cancer patient. TILs were expanded ex vivo from minced tumors without feeder cells in the modified TIL therapy regimen. Patients underwent low-dose cyclophosphamide lymphodepletion followed by TIL infusion without intravenous IL-2. The primary endpoint was safety; the secondary endpoints included objective response rate, duration of response, and T cell persistence.ResultsIn matched patient-derived xenografts (PDX) models, homologous TILs efficiently reduced tumor size (p < 0.0001) and underwent IL-2 absence in vivo. In the clinical section, all enrolled patients received TIL infusion using a modified TIL therapy regimen successfully with a manageable safety profile. Five (36%, 95% CI 16.3–61.2) out of 14 evaluable patients experienced objective responses, and three complete responses were ongoing at 19.5, 15.4, and 5.2 months, respectively. Responders had longer overall survival (OS) than non-responders (p = 0.036). Infused TILs showed continuous proliferation and long-term persistence in all patients and showed greater proliferation in responders which was indicated by the Morisita overlap index (MOI) of TCR clonotypes between infused TILs and peripheral T cells on day 14 (p = 0.004) and day 30 (p = 0.004). Higher alteration of the CD8+/CD4+ ratio on day 14 indicated a longer OS (p = 0.010).ConclusionsOur modified TIL therapy regimen demonstrated manageable safety, and TILs could survive and proliferate without IL-2 intravenous administration, showing potent efficacy in patients with advanced gynecologic cancer.Trial registrationNCT04766320, Jan 04, 2021.

Evaluating geometric measurement accuracy based on 3D model reconstruction of nursery tomato plants by Agisoft photoscan software

Measuring the vegetation structure of a plant with the help of 3D images is a non-destructive method that can be used to monitor the plant’s status during the growing season. Structure from motion (SfM) is a popular optical distance measurement method that uses 2D images to create 3D models. Identifying factors that influence the precision of SfM is important due to its increasing use in phenotyping. The primary objectives of this study were, i) to scrutinize the impact of imaging parameters—including, color checkerboard location, overlap size of images, and background filtering—on the quality indices of 3D models, and ii) to attain precise measurements of leaf area, stem diameter, and height through the combination of images captured from different camera shooting angles. The three nursery tomato plants were photographed at every five-degree rotation of the turntable, five different locations of color checkerboards, and five camera shooting angles. Results indicated the color checkerboard’s presence and position affect the quality indices of the 3D models. Visually and by the lowest mean keypoint size value, the least noisy 3D model was obtained when the wall of the plant pot was covered with a checkerboard. When the base-to-distance (b/y) ratio as the image overlap index increased from 0.1 to 0.2, the generation time of the 3D models decreased by more than two times. Optimal Mean Absolute Percentage Error (MAPE) values of 1.08 %, 1.01 %, and 1.38 % were achieved for the estimation of leaf area, stem diameter, and height, respectively. This was recorded by using images taken at 0°, 30°, and 105° vertical azimuth angles. Constructing a 3D model by integrating images captured from other angles or more azimuth angles represents numerous visual challenges and leads to problems of point mismatch, which affects the accuracy of measurements.

Climate change will likely facilitate invasion of Asian orchid Eulophia graminea into new areas

Climate change plays an increasing role in the global biodiversity crisis. Alteration in local climatic conditions not only can negatively affect native biodiversity but also can accelerate the introduction and spread of invasive species. In this study the ecological niche modelling approach was used to evaluate possible changes in the distribution of suitable niches of invasive orchid Eulophia graminea within its native (Asia) and non-native geographical range (America, Australia). We mapped the current potential range of this species and analysed three various projections of future climate (for 2100) each with four different climate change scenarios (SSPs). Calculated niche overlap indexes indicated low similarity of niches occupied by native and invasive populations of E. graminea and Australian populations seem to be the most unique, while American and Asian groups share partially similar niches. The occurrence of the American population of E. graminea was correlated especially with the temperature seasonality, while the Asian and Australian populations with annual precipitation and precipitation of the wettest quarter. As indicated in our analyses within Asia and America, E. graminea does not occupy all climatically suitable niches. On the other hand, in Australia the species studied already occupies all appropriate niche space. Climate change will likely be favorable for species studied to expand its range if the biotic components of its niche space (e.g., mycorrhizal fungi) will respond similarly. The most significant range expansion is predicted to occur in Australia which is interesting considering the marginally suitable habitats that E. graminea currently occupies.

Impacts of locust feeding on interspecific relationships and niche of the major plants in Inner Mongolia grasslands

Oedaleus decorus asiaticus (O. asiaticus), the dominant species of steppe locust, plays a crucial role in driving the dynamic changes of the grassland ecosystem. However, there are a limited number of studies on the impact of locust feeding on the relationship of the major plants in the species community. This study has employed the Shannon-Wiener index, Pianka index, and the maximum information coefficient (MIC) to assess the impact of O. asiaticus feeding on the community structure and interspecific relationships in the grasslands of Inner Mongolia. The chosen indices measured niche breadth, niche overlap, and interspecies correlation. The topological network structure between the main species was further analyzed. The results indicated that: 1) locust gnawing expands the niche width of major species and increases the niche overlap index of food-loving species; 2) the feeding of locusts reduces the overall correlation between species but increases the interspecific relatedness between food-loving species and other species. 3) the number of links in the species topological network structure is reduced due to locust gnawing.

Mixed eigenstates in the Dicke model: Statistics and power-law decay of the relative proportion in the semiclassical limit.

How the mixed eigenstates vary when approaching the semiclassical limit in mixed-type many-body quantum systems is an interesting but still less known question. Here, we address this question in the Dicke model, a celebrated many-body model that has a well defined semiclassical limit and undergoes a transition to chaos in both quantum and classical cases. Using the Husimi function, we show that the eigenstates of the Dicke model with mixed-type classical phase space can be classified into different types. To quantitatively characterize the types of eigenstates, we study the phase space overlap index, which is defined in terms of the Husimi function. We look at the probability distribution of the phase space overlap index and investigate how it changes with increasing system size, that is, when approaching the semiclassical limit. We show that increasing the system size gives rise to a power-law decay in the behavior of the relative proportion of mixed eigenstates. Our findings shed more light on the properties of eigenstates in mixed-type many-body systems and suggest that the principle of uniform semiclassical condensation of Husimi functions should also be valid for many-body quantum systems.