Coexistence Mechanisms Research Articles

Temporal Foraging and Ranging Patterns Suggested the Niche Partitioning of Two Sympatric Herbivores, Axis axis and Bubalus bubalis, in the Nijhum Dweep National Park of Bangladesh

For proper conservation measures and to elucidate coexistence mechanism of sympatric herbivore, we assessed the temporal foraging and ranging patterns of the Axis axis (spotted deer) and feral and/or semi domesticated Bubalus bubalis (buffalos) in the Nijhum Dweep National Park (NDNP) of Bangladesh. We have collected the data by day long scan sampling method for 12 months. We found that spotted deer and buffalos, respectively, spent 50.34% and 36.41% of their total day time in foraging. To avoid clash with the larger sized buffalos in the grazing ground, the spotted deer choose a slightly different time for grazing. At least three foraging peaks were found for spotted deer, whereas, buffalos showed two foraging peaks in a day. More importantly, spotted deer relied more on browsing for their food collection although they are natural gazer, whereas, buffalos relied more on their natural grazing habit for food collection. Spotted deer spent most of their time inside the forest and forest edges, whereas, buffalos mostly spent their time in the open grazing grounds. The range of total distance moved (TDM) per day for spotted deer and buffalos was 1.56 to 2.67 km and 1.02 to 3.30 km, respectively. The total area ranged (TAR) per day were 0.23 km2 to 0.8 km2 for spotted deer and 0.03 km2 to 0.35 km2 for buffalos. Although, these two parameters varied seasonally for both species, only in case of TAR of spotted deer the variation was statistically significant ( P < 0.05 ). We conclude that because of the presence of a larger sympatric herbivore, the spotted deer did some alterations in their temporal foraging and ranging pattern (TFRP) to survive in the small island which has very limited resources for their existence and survival.

Elucidating the role of competition in driving spatial and trophic niche patterns in sympatric juvenile sharks

The coexistence of ecologically and morphologically similar species is often facilitated by the partitioning of ecological niches. While subordinate species can reduce competition with dominant competitors through spatial and/or trophic segregation, empirical support from wild settings, particularly those involving large-bodied taxa in marine ecosystems, are rare. Shark nursery areas provide an opportunity to investigate the mechanisms of coexistence. We used experimental and field studies of sympatric juvenile sharks (blacktip reef shark, Carcharhinus melanopterus; sicklefin lemon shark, Negaprion acutidens) to investigate how competitive ability influenced realized niches at St. Joseph Atoll, Seychelles. Captive trials revealed that sicklefin lemon sharks were dominant over blacktip reef sharks, consistently taking food rewards. In the field, blacktip reef sharks were captured over a broader area than sicklefin lemon sharks, but daily space use of actively tracked sharks showed a high degree of overlap across microhabitats. While stomach contents analysis revealed that blacktip reef shark diets included a broader range of prey items, stable isotope analysis demonstrated significantly higher mean δ13C values for sicklefin lemon sharks, suggesting diverging dietary preferences. Overall, our results matched theoretical predictions of subordinate competitors using a greater range of habitats and displaying broader feeding niches than competitively dominant species. While separating the realized and fundamental niche of marine predators is complicated, we provide evidence that resource partitioning is at least partially driven by interspecific competition.

Intraguild predation is increased in areas of low prey diversity in a generalist predator community.

Niche differentiation and intraguild predation (IGP) can allow ecologically similar species to coexist, although it is unclear which coexistence mechanism predominates in consumer communities. Until now, a limited ability to quantify diets from metabarcoding data has precluded the use of sequencing data to determine the relative importance of these mechanisms. Here, we pair a recent metabarcoding quantification approach with stable isotope analysis to examine diet composition in a wolf spider community. We compare the prevalence of resource partitioning and IGP in these spiders and test whether factors that influence foraging performance, including individual identity, morphology, prey community and environmental conditions, can explain variation in diet composition and IGP. Extensive IGP is likely the primary coexistence mechanism in this community, and other factors to which foraging variation is often attributed do not explain diet composition and IGP here. Rather, IGP increases as prey diversity decreases. Foragers are driven to IGP where resource niches are limited. We highlight the need to examine how drivers of predator-prey interaction strengths translate into foraging in natural systems.

Temporal Response of Mesocarnivores to Human Activity and Infrastructure in Taihang Mountains, Central North China: Shifts in Activity Patterns and Their Overlap

Mesocarnivores play essential roles in terrestrial ecosystems, but anthropocentric disturbances have profoundly transformed their intraguild interactions worldwide. In this study, we explored how a guild of four mesocarnivores (red fox Vulpes vulpes, leopard cat Prionailurus bengalensis, Asian badger Meles leucurus, and hog badger Arctonyx collaris) partition their temporal niche in the temperate montane forests in North China under different human influences. We conducted a systemic camera-trapping survey on the study species in the central Taihang Mountains from 2016 to 2020. With an extensive survey effort of 111,063 camera-days from 187 camera stations, we obtained 10,035 independent detections of the four mesocarnivores and examined the activity patterns of each species under different levels of human disturbance and their overlaps. The results showed that, while the leopard cat and the badgers shifted their activity towards nocturnality, the red fox showed no significant change. The leopard cat's degree of nocturnality varied between growing and non-growing seasons, likely a response to avoid humans and other competitors. However, the activity overlaps between species pairs demonstrated no statistically significant difference, indicating a long-developed coexistence mechanism that is homogenous across the landscape. Demonstrating how mesocarnivores shift activity patterns in response to human risks while partitioning resources, this study enhances our understanding of mesocarnivore behavioral changes and interspecific interactions at human-nature interfaces.

Topological dual and extended relations between networks of clathrate hydrates and Frank-Kasper phases

Clathrate hydrates are a class of ordered structures that are stabilized via the delicate balance of hydrophobic interactions between water and guest molecules, of which the space-filling network of hydrogen-bonded (H-bonded) water molecules are closely related to tetrahedrally close-packed structures, known as Frank-Kasper (FK) phases. Here we report an alternative way to understand the intricate structures of clathrate hydrates, which unveils the diverse crystalline H-bonded networks that can be generated via assembly of one common building block. In addition to the intrinsic relations and pathways linking these crystals, we further illustrate the rich structural possibilities of clathrate hydrates. Given that the topological dual relations between networks of clathrate hydrates and tetrahedral close-packed structures, the descriptors presented for clathrate hydrates can be directly extended to other ordered materials for a more thorough understanding of their nucleation, phases transition, and co-existence mechanisms.

Coexistence patterns of sympatric giant pandas (Ailuropoda melanoleuca) and Asiatic black bears (Ursus thibetanus) in Changqing National Nature Reserve, China

Similar species may co-occur in sympatry because of the partitioning of habitat use and resources at different spatial and temporal scales. Understanding coexistence patterns of species may contribute to further uncovering the underlying coexistence mechanisms, and ultimately benefit the conservation of threatened species. In this study, camera trapping was used to investigate spatial and temporal activity patterns of sympatric giant pandas (Ailuropoda melanoleuca) and Asiatic black bears (Ursus thibetanus) in Changqing National Nature Reserve in Qinling Mountains, China. Our study obtained 281 independent detections of giant pandas and 185 of Asiatic black bears during 93,606 camera-trap days from April 2014 to October 2017. We performed occupancy modeling and temporal overlap analyses to examine the spatial-temporal relationships between pandas and bears, and results showed that: (1) giant pandas had higher detection probabilities than Asiatic black bears, while having lower occupancy probabilities; (2) Elevation positively predicted giant panda and negatively predicted Asiatic black bear occupancy, understory vegetation type negatively predicted giant panda occupancy, and distance to nearest settlement positively predicted Asiatic black bear occupancy; (3) giant pandas were more active in spring and winter, while Asiatic black bears were more active in summer, and the two species had low spatial overlap with one another throughout the year; (4) both giant pandas and Asiatic black bears showed mainly diurnal activity patterns, and had high temporal overlap with one another in spring and moderate temporal overlap with one another in autumn. Our results provide detailed information of the spatial and temporal ecology of sympatric giant pandas and Asiatic black bears in the Qinling Mountains of China, which could act as a guide to construct conservation priorities as well as design efficient management programs.

Performance of Offloading Strategies in Collocated Deployments of Millimeter Wave NR-U Technology

5G New Radio (NR) technology operating in millimeter wave (mmWave) band is expected to be utilized in areas with high and fluctuating traffic demands such as city squares, shopping malls, etc. The latter may result in quality of service (QoS) violations. To deal with this challenge, 3GPP has recently proposed NR unlicensed (NR-U) technology that may utilize 60 GHz frequency band. In this paper, we investigate the deployment of NR-U base stations (BS) simultaneously operating in licensed and unlicensed mmWave bands in presence of competing WiGig traffic, where NR-U users may use unlicensed band as long as session rate requirements are met. To this aim, we utilize the tools of stochastic geometry, Markov chains, and queuing systems with random resource requirements to simultaneously capture NR-U/WiGig coexistence mechanism and session service dynamics in the presence of mmWave-specific channel impairments. We then proceed comparing performance of different offloading strategies by utilizing the eventual session loss probability as the main metric of interest. Our results show non-trivial behaviour of the collision probability in the unlicensed band as compared to lower frequency systems. The baseline strategy, where a session is offloaded onto unlicensed band only when there are no resources available in the licensed one, leads to the best performance. The offloading strategy, where sessions with heavier-than-average requirements are immediately directed onto unlicensed band results in just <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$2\!-\!5\%$</tex-math></inline-formula> performance loss. The worst performance is observed when sessions with smaller-than-average requirements are offloaded onto unlicensed band.

Density, Temperature, and Comingled Species Affect Fitness within Carrion Communities: Coexistence in Phormia regina and Lucilia sericata (Diptera: Calliphoridae)

Blow fly (Diptera: Calliphoridae) interactions vary between competition and facilitation. Female blow flies engage in aggregated egg-laying, resulting in larval feeding masses differing in density and species composition. Numerous species are abundant within the same season, and some oviposit near or directly on eggs of other species, modifying their oviposition location choice depending on the presence or absence of other species. The ability to coexist on carrion, a temporary resource, was successfully attributed to resource, spatial, and temporal heterogeneity. Despite these broad categorizations, the specific mechanisms of coexistence within blow fly communities require further investigation. This study investigates variation in temperature and larval density as potential mechanisms of coexistence between two forensically important blow fly species: Lucilia sericata Meigen and Phormia regina Meigen (Diptera: Calliphoridae). Larval density, species ratio mix, and ambient temperature during development were manipulated in the presence of conspecifics and heterospecifics in the laboratory, and the fitness of each species was measured. In heterospecific treatments, the survival and body size of P. regina increased even at high ambient temperatures. In contrast, the survival of L. sericata remained unaffected by density or presence of heterospecifics, whereas body size increased in L. sericata-dominated heterospecific treatments depending on temperature and density. The negative effects of density were observed at high ambient temperatures, suggesting that density impacts are a function of ambient temperature. Overall, species coexistence was dependent on temperature, which mediated the outcome of species interactions.

A trade-off between space exploration and mobilization of organic phosphorus through associated microbiomes enables niche differentiation of arbuscular mycorrhizal fungi on the same root.

Ecology seeks to explain species coexistence, but experimental tests of mechanisms for coexistence are difficult to conduct. We synthesized an arbuscular mycorrhizal (AM) fungal community with three fungal species that differed in their capacity of foraging for orthophosphate (P) due to differences in soil exploration. We tested whether AM fungal species-specific hyphosphere bacterial assemblages recruited by hyphal exudates enabled differentiation among the fungi in the capacity of mobilizing soil organic P (Po). We found that the less efficient space explorer, Gigaspora margarita, obtained less 13C from the plant, whereas it had higher efficiencies in Po mobilization and alkaline phosphatase (AlPase) production per unit C than the two efficient space explorers, Rhizophagusintraradices and Funneliformis mosseae. Each AM fungus was associated with a distinct alp gene harboring bacterial assemblage, and the alp gene abundance and Po preference of the microbiome associated with the less efficient space explorer were higher than those of the two other species. We conclude that the traits of AM fungal associated bacterial consortia cause niche differentiation. The trade-off between foraging ability and the ability to recruit effective Po mobilizing microbiomes is a mechanism that allows co-existence of AM fungal species in a single plant root and surrounding soil habitat.

Food webs reveal coexistence mechanisms and community organization in carnivores

Globally, massive carnivore guild extirpations have led to trophic downgrading and compromised ecosystem services. However, the complexity of multi-carnivore food webs complicates accurate identification of species interactions and community organization. Here, we used fecal DNA metabarcoding to investigate three communities that together encompass eight large- and meso-carnivore species and their 44 prey taxa of the Qinghai-Tibet Plateau (QTP), one of the last places on Earth that still harbors intact carnivore assemblages. Quantitative food-web analyses revealed pronounced interspecific variations in the carnivores' prey compositions and dietary partitioning both between and within guilds. Additionally, body masses of the carnivores and their prey exhibited consistent hump-shaped correlations across communities. Overall, differences in prey diversity, size category, and proportional utilization among the carnivore species result in trophic niche segregation that likely promotes carnivore coexistence in the harsh QTP environment. Network structure analyses detected significant modularity in all food webs but nestedness in only one. Furthermore, network characterization identified pikas (Ochotona spp.), bharal (Pseudois nayaur), and domestic yak (Bos grunniens) as potential keystone prey across the areas. Our results paint a holistic and detailed picture of the QTP carnivore assemblages' trophic networks and demonstrate that the combined use of the molecular dietary approach and network analysis can generate structural insights into carnivore coexistence and can identify functionally important species in complex communities. Such knowledge can help safeguard carnivore guild integrity and enhance community resilience to environmental perturbations in the sensitive QTP ecosystems.

Spatial determinants of tree recruitment in mixed stands in southeastern Poland- silver fir's interaction with lowland tree species

Silver fir (Abies alba Mill.) is a typical mountain tree species, but it can also grow in lowlands below 300 m a.s.l., where it must coexist with a variety of competitors. Much less were studied in the northeastern part of its natural range, where annual precipitation varies between 500 and 600 mm, distinctly less than in the mountains. The general objective of this study was to investigate the regeneration process of silver fir in mixed lowland forests in regions with water shortage. The evaluation of spatial relationships between old, dominant and newly established trees was used to clarify the mechanisms of tree species coexistence. The study was conducted in managed and protected stands in Janów Forests in the southeastern part of Poland. We selected mature forest stands (oldest trees older than 100 years) representing three types of mixed stands in nature reserves, as well as in comparable managed forests. Data was collected on 500 m2 sample plots established randomly in each stand category (20 sample plots × 6 stands). Silver fir as the target tree showed statistically significant segregation from other species in 15 cases. Small silver fir trees were associated with large pines in two forest types and segregated form large firs in one. The spatial relationships between fir and black alder were negative. Black alder was the second species with the most statistically significant spatial relationships with other tree species (11 cases). Alders separated from large pines and large firs and from medium and small silver firs. Strong segregation of medium-sized hornbeam from the small class of silver fir was observed. Our study showed that silver fir natural regeneration and colonization of new areas at the northeastern limit of its range are limited by low seed rain density, interactions with other competing species, and local site conditions. Areas with moderately high water table are potentially suitable for fir regeneration, but black alder has a competitive advantage in wetter parts of forest stand. The major advantage of such sites is the absence of beech populations, which are an important competitor to fir in the central European mountains, but a likely equally important limitation would be the presence of hornbeam populations. Our results suggest that less intensive cuttings at carefully selected places are more conducive to fir regeneration than more intensive salvage cuttings.

Multiple canopy opening effects on recruited saplings in a typhoon‐disturbed tropical rainforest, Taiwan

AbstractTo investigate the influence of multiple canopy openings on the composition and diversity of recruited saplings in a forest frequently disturbed by typhoons. We conducted tree‐by‐tree censuses (diameter at breast height ≥ 1 cm) and mapped gaps (canopy height &lt; 5 m) in 1993, 2000, 2008, and 2013 in a tropical mountain zonal foothill evergreen broad‐leaved forest in Nanjenshan Nature Reserve, Taiwan. We analyzed the composition and diversity of recruited saplings within a 2.1 ha plot (840 sampling quadrats (5 m × 5 m)) with variable numbers of canopy openings recorded during the study period. Composition of recruited saplings was dissimilar between quadrats that stayed opened and those that stayed closed throughout the study period (pairwise similarity estimates C02 = 0.52, 95% CI = 0.38–0.66). The quadrats under closed canopy had high diversity when weighting rare species (species richness), whereas quadrats with one or two gap opening records during the past 20 years had high diversity when weighting the abundance of species. Although canopy openings provided establishment conditions for saplings of some shade‐intolerant species, due to the nature of small gap size, such habitats do not favor the dominance of shade‐intolerant species. Even in a frequently disturbed forest, species composition and richness of recruited saplings were mainly contributed by shade‐tolerant species. Although multiple canopy openings facilitated the establishment of shade‐intolerant species, species diversity in the study forests is possibly mainly mediated by coexistence mechanisms of those shade‐tolerant species rather than light‐gap‐related species strategies.

Nitrogen enrichment and foliar fungal pathogens affect the mechanisms of multispecies plant coexistence.

Changes in resources (e.g., nitrogen) and enemies (e.g., foliar pathogens) are key drivers of plant diversity and composition. However, their effects have not been connected to the niche and fitness differences that determine multispecies coexistence. Here, we combined a structuralist theoretical approach with a detailed grassland experiment factorially applying nitrogen addition and foliar fungal pathogen suppression to evaluate the joint effect of nitrogen and pathogens on niche and fitness differences, across a gradient from two to six interacting species. Nitrogen addition and pathogen suppression modified species interaction strengths and intrinsic growth rates, leading to reduced multispecies fitness differences. However, contrary to expected, we also observed that they promote stabilising niche differences. Although these modifications did not substantially alter species richness, they predicted major changes in community composition. Indirect interactions between species explained these community changes in smaller assemblages (three and four species) but lost importance in favour of direct pairwise interactions when more species were involved (five and six). Altogether, our work shows that explicitly considering the number of interacting species is critical for better understanding the direct and indirect processes by which nitrogen enrichment and pathogen communities shape coexistence in grasslands.

A study of periodic solutions and periodic background solutions for the reverse-space–time modified nonlinear Schrödinger equation

The modified nonlinear Schrödinger (MNLS) equation is used to describe the effect of femtosecond pulses and nonlinear dispersion in long single-mode fibers and the propagation of modulated Alfvén waves along a magnetic field in a cold plasma. Under investigation in this paper is its nonlocal reverse-space–time type, extending it to the more general case, which has much physical significance in the field of nonlocal nonlinear dynamical systems. Through constructing nonlocal type Darboux transformations (DTs), we will derive a series of new solutions as follows: (1)Bright and dark solitons on plane wave backgrounds, single and double periodic solutions; (2)Breather, rogue wave solutions and their coexistence mechanism on single periodic backgrounds via odd-fold DTs; (3) Bright and dark breather-like solutions on single periodic backgrounds, breather, rogue wave solutions and their degenerate and coexistence forms on double periodic backgrounds via even-fold DTs. In addition, we will discuss dynamic behaviors of those solutions through graphic simulations.

Some of the Mechanisms for Coexistence of Tree Species Diversity in Tropical Forests: A Review of Effects of Tree Density Dependence

Tree communities contribute to maintenance of species diversity in tropical forests. Coexistence of many tree species is not without competition. Therefore, coexistence of tree species and size diversities occur sequentially or simultaneously in tropical natural forests. Understanding coexistence and competition mechanisms of tree species requires knowledge of interactions within and between species. However, many conservation efforts and strategies failed due to inability to identify and maintain functional coexistence mechanisms among tree species in the forest. Also, most trees died because of pressure on their habitats and not because of limiting growth resources. Hence, species identity, minimum distance and size of the neighbouring trees which are responsible for coexistence of competing trees in most tropical forests have not been explicitly reviewed. Therefore, this review evaluated some of the density dependent mechanisms for coexistence of tree species alpha diversity in tropical forests. Many interactive mechanisms are responsible for coexistence tree species in tropical forests. Inter- and intra-specific competitions are the most significant and both facilitate positive and negative density dependence. Therefore, switching from negative to positive density dependence may occur in some situations. Positive and negative density effects regulate species abundance and coexistence through conspecific and heterospecific structures. Aggregates of conspecific and heterospecific neighbours constitute forest spatial structure. Negative density interactions are mutually exclusive and basically ranged from effect of species identity of neighbours, distance to neighbours and tree size of the neighbours to reference trees in the community structures. Some mechanisms shorten distances for heterospecific than conspecific interactions. Conspecific structures improved survival and growth of rare tree species. Interactive mechanisms in tree community and population structures facilitate species diversity and size inequality, respectively.

The uniaxial zero thermal expansion and zero linear compressibility in distorted Prussian blue analogue RbCuCo(CN)6.

The uniaxial zero thermal expansion (ZTE) in distorted Prussian blue analogue (PBA) RbCuCo(CN)6 is reproduced by employing first-principles calculations, which agrees well with the experimental data. Also, the zero linear compressibility (ZLC) behavior in RbCuCo(CN)6 can be found. The special Jahn-Teller distortion introduced by Cu2+ in RbCuCo(CN)6 is noticed by investigating the change of the local structure with temperature and hydrostatic pressure. The lattice thermal conductivity (LTC) and phonon group velocity of RbCuCo(CN)6 are studied, where the LTC and phonon group velocity are significantly anisotropic. Especially, RbCuCo(CN)6 exhibits a quite low LTC, and its c-axis shows a characteristic of glasslike LTC at low temperatures. Our work facilitates a deep understanding of the coexistence mechanisms of uniaxial ZTE and ZLC properties in RbCuCo(CN)6.

Trophic resources use pathways between two coexisting freshwater shrimp (Palaemon argentinus and Macrobrachium borellii)

Context A better understanding of the use of different trophic pathways as a mechanism for adjusting interactions between coexisting omnivorous decapod species may help define the extent of their influence on energy flows in freshwater ecosystems. Aims Analyse the patterns of use of the benthic and littoral pathways by Macrobrachium borellii and Palaemon argentinus during a hydrological cycle in lakes of the middle Paraná River. Methods The study was conducted during one high-water (HW) and one low-water (LW) period in three lakes permanently connected to the middle Paraná River. We calculated the relative contributions of potential basal resources (benthic and littoral) to each species for each lake and hydrological period using mixing models. Key results It was observed that M. borellii feeds more in the littoral pathway and P. argentinus in the benthic pathway, especially in low water where we observed that the partitioning of resources was more pronounced. Conclusion The more aggessive species, M. borelli, during HW period quickly utilises the bioavailable material. Trophic dynamics and resource use are part of the coexistence mechanisms of both decapod species. Implications This may have important consequences in the aquatic trophic webs in which these organisms participate, because when segregating the use of resources, they intervene in different energetic pathways.

同域分布的野猪与狍活动节律及与月光周期的关系

PDF HTML阅读 XML下载 导出引用 引用提醒 同域分布的野猪与狍活动节律及与月光周期的关系 DOI: 10.5846/stxb202203100582 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 穆棱红豆杉国家级自然保护区野生动物监测;黑龙江省省属科研院所科研业务费项目(CZKYF2021B002);藏财预指(2020-11-05) Activity rhythm of wild boar and roe deer and its relationship with moonlight cycle in sympatric distribution Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:完全的竞争者不能共存,物种间生态位分化是同域物种长期稳定共存的基础。不同物种在同一分布区时间生态位的分化对其共存至关重要。为研究同域分布物种的共存机制,在2018年11月到2021年7月利用远红外相机监测技术对穆棱东北红豆杉国家级自然保护区同域分布的野猪(Sus scrofa)和狍(Capreolus pygargus)进行了野外监测研究,并利用核密度估计方法和雅各布斯选择指数(JSI)对日活动节律和一段时间内的活动周期选择进行了评估,同时还利用非参数检验评估了2个物种的活动与月光周期的关系。研究结果表明,狍不管在全年还是在不同的季节,日活动节律均为双峰模式,而野猪的活动模式表现出明显的可塑性,在全年和冷季为单峰型,暖季为双峰型,二者在日活动节律上的重叠程度较高(Dhat>0.59),在暖季的重叠系数最高(Dhat=0.65)。此外,在时间段的选择上,狍在全年和冷季更喜欢在黎明和黄昏活动(0.170.32),而野猪活动在全年和冷季对白天和黄昏的选择更多(JSI>0.3),暖季则更喜欢在白天活动(JSIday=0.86),二者在夜晚的活动都较少(JSInight< 0),其中野猪尤为明显(JSInight< -0.63)。狍在各月光周期间的出现频次存在显著差异(P<0.05),满月期活动较频繁,下弦月期活动频次最少,而野猪的活动与月光周期的相关性较弱(P>0.05)。研究野猪和狍的时间重叠,为研究大型食肉动物与猎物的互作关系奠定了基础。 Abstract:Complete competitors cannot coexist, and the long-term stable coexistence of sympatric species is based on interspecific niche differentiation. The temporal niche differentiation of different species in the same distribution area is very important for their coexistence. In order to study the coexistence mechanism of sympatric species, we used camera trapping to conduct field survey on wild boar (Sus scrofa) and roe deer (Capreolus pygargus), which were both distributed in the same area in the Muling Japanese Yew National Nature Reserve from November 2018 to July 2021. We used the kernel density estimation method and the Jacobs Selection Index (JSI) to evaluate the daily activity rhythm and the selection for a period of the diel cycle, and also analyzed the relationship between the activities of the two species and the moonlight cycle by nonparametric tests. The results showed that the daily activity rhythm of roe deer was two higher peaks of activity in the whole year or in different seasons. Nevertheless, the activity pattern of wild boar showed obvious plasticity, which was unimodal in the whole year and the cold season, and bimodal in the warm season. The results showed that there was a moderate degree of overlap between them in daily activity rhythm (Dhat>0.59), and the degree of overlap was the highest (Dhat=0.65, 0.55-0.75) in warm season. In addition, in terms of time period selection, the roe deer were more likely active at dawn and dusk in the whole year and the cold season (0.170.32). However, the wild boar activities were more frequent during the day and dusk in the whole year and the cold season (JSI>0.3), and preferred to be active during the day in the worm season (JSIday=0.86). Furthermore, two species of wild boar and roe deer were less active at night (JSInight<0), especially for wild boar (JSInight<-0.63). The frequency of roe deer behaviors differed significantly by moon phase (P<0.05), and roe deer were more active during the full moon period. However, the activity of wild boar was not related to the moonlight cycle (P>0.05). The study of temporal niche overlap of wild boar and roe deer provides research basis for the interaction between large carnivores and prey. 参考文献 相似文献 引证文献

Coexistence mechanisms of negative differential resistance and resistive switching effects in a WOx-based memristor

Metal oxide memristors are highly desirable for bionic synaptic applications.

Population dynamics of three cloud forest ferns of different growth form

AbstractCloud forests are highly diverse mountain ecosystems, but habitat loss and fragmentation threaten many species with extinction. Demographic parameters are essential to implement effective conservation actions and to understand the mechanisms of species coexistence, but there are very few population models with transition matrices for fern species. We evaluated the demographic dynamics of three coexisting fern species of different growth form in a cloud forest in eastern central Mexico for six years. The matrix analyses showed that the populations of a trunk‐forming fern (Cyathea divergens) and a short caulescent fern (Marattia laxa) were stable while the population of a trunkless, herbaceous fern (Parablechnum schiedeanum) was decreasing. Survival was the demographic process of the life cycle that contributed the most to the population growth of the three species. As expected, with shorter longevity and high precocity, P. schiedeanum exhibited the demographic pattern of herbaceous species. In contrast, with greater longevity and a longer maturation period, the demography of C. divergens and M. laxa was more comparable with that of tree species. Our results support the hypothesis that the demography of the tropical fern species can be compared with life‐history strategies of angiosperms and gymnosperms.