The formation of pantropical intercontinental disjunction(PID)in plants has generally been attributed to vicariance,boreotropical migration,and long-distance dispersal.However,this pattern has primarily been examined ...The formation of pantropical intercontinental disjunction(PID)in plants has generally been attributed to vicariance,boreotropical migration,and long-distance dispersal.However,this pattern has primarily been examined in herbs,shrubs,and trees,and less commonly studied in interlayer plant taxa.Here we examined evolutionary processes that resulted in the PID of a pantropical woody liana,Uncaria(Rubiaceae).We first constructed a comprehensive phylogeny by employing 73 plastid protein-coding sequences from 29 accessions of Uncaria(including 16 newly sequenced)from different continents.We then inferred divergence time,history and ecological niche evolution of this genus.Our results showed that Uncaria consisted of four well-supported clades that belonged to two geographically distinct lineages:the Asia-Oceania lineage and the Afro-Neotropical lineage.Biogeographic reconstruction showed this genus likely originated in Asia during the early Miocene(ca.19.03 Ma)and the Middle Miocene Climatic Optimum may have triggered the early diversification of Uncaria.Due to its recent origin and small seeds with long wings,wind or water-mediated long-distance dispersal may have contributed to the distribution of Uncaria in tropical Oceania(via stepping-stone dispersal)and tropical Africa and America(by transoceanic dispersal).Our findings also indicate that diversification of Uncaria was primarily driven by ecological niche divergence,particularly climatic factors.Our study emphasizes the dual role of climatic niche divergence and long-distance dispersal in shaping the PID of Uncaria,providing references for many other extant lineages with similar distributions.展开更多
Seed long-distance dispersal(LDD) events are typically rare, but are important in the population processes that determine large-scale forest changes and the persistence of species in fragmented landscapes. However, pr...Seed long-distance dispersal(LDD) events are typically rare, but are important in the population processes that determine large-scale forest changes and the persistence of species in fragmented landscapes. However, previous studies focused on species dispersed via animal-mediated LDD, and ignored those dispersed by wind. The aim of this study was to assess the effects of canopy openness, edge, seed source, and patch tree density on the LDD of seeds by wind in forest. We collected birch seeds, a typical wind-dispersed species, throughout a larch plantation. We then assessed the relationship between birch LDD and each factor that may influence LDD of seeds by wind including distance to edge, canopy openness size, distance to mature forest, and the tree density of the larch plantation. We used univariate linear regression analysis to assess the influence of those factors on birch LDD, and partial correlations to calculate the contribution of each factor to LDD. The results showed that both canopy openness and edge had significant influences on birch LDD. Specifically, a negative relationship was observed between distance to edge and birch LDD, whereas there was a positive correlation between canopy openness size and LDD. In contrast, the distance to the mature forest was not correlated with birch LDD. Our results suggest that patch tree density could potently affect the probability of LDD by wind vectors, which provides novel and revealing insights regarding the effect of fragmentation on wind dynamics. The data also provide compelling evidence for the previously undocumented effect of habitat fragmentation on wind-dispersed organisms. As such, these observations will facilitate reasonable conservation planning, which requires a detailed understanding of the mechanisms by which patch properties hamper the delivery of seeds of wind-dispersed plants to fragmented areas.展开更多
The relative contribution of long-distance dispersal and local diffusion in the spread of invasive species has been a subject of much debate. Invasion of the intertidal mudflats by Spartina alterniflora is an ideal ex...The relative contribution of long-distance dispersal and local diffusion in the spread of invasive species has been a subject of much debate. Invasion of the intertidal mudflats by Spartina alterniflora is an ideal example of stratified diffusion, involving both long-distance dispersal of seeds and local diffusion due to clonal growth. In conjunction with experimental data on range radius-versus-time curve, a traveling wave equation-based model is used to investigate the sensitivity of the spread rate of exotic S. alterniflora to parameters of long distance dispersal (c, maximum colonial establishment rate) and local colony diffusion (r, intrinsic growth rate) at two tidal marshes, the Eastern Chongming and the Jiuduansha Islands, at the Yangtze River estuary. Both Eastern Chong ming and Jiuduansha Islands are now national natural reserves in China, which were established in 2005. However, the mudflats and salt marshes in the two reserves are now heavily infested with introduced S. alterniflora, which may threaten the estuarine ecosystems and their biodiversity. S. alterniflora was first found in 1995 on Chongming. For rapid sediment accretion in mudflats in the estuary, S. alterniflora was also intentionally introduced to Jiuduansha in 1997 and Chongming in 2001, which has led to a rapid range expansion in the estuary. Our results show that range expansion of species with stratified diffusion is affected by both long-distance dispersal and local colony diffusion, and that there is a critical c*, below which the spread rate is more influenced by long-distance dispersal than by local diffusion. After applying this model to the invasion of S. alterniflora in the Yangtze River estuary, we derive that c = 1.7 × 10-3, c* = 0.126 and c = 4.8 × 10-3 km-2·yr-1, c* = 0.140 km-2·yr-1 at Chongming and Jiuduansha (Shanghai), respectively. Our results suggest that the range spread of S. alterniflora in the Yangtze River estuary is more influenced by long-distance dispersal than local colony diffusion, and that S. alterniflora generates about 1.7 × 10-3 to 4.8 × 10-3 colonies per square kilometers per year. This study provides important information about dispersal dynamics of S. alterniflora that may be useful for finding optimal control strategies. ·展开更多
The study of land bridge based on con- tinental drift1) and long-distance dispersal are gaining increasing attention in biogeography. We review several major dispersal theories including the Mal- pigiacea route, patte...The study of land bridge based on con- tinental drift1) and long-distance dispersal are gaining increasing attention in biogeography. We review several major dispersal theories including the Mal- pigiacea route, patterns of chameleon dispersal and the floating island model. The Malpigiaceae route indicates that the Malpigiaceae family originated in northern South America and that members of several clades migrated into North America and subsequently moved via north Atlantic land connections into the Old World starting in the Eocene. This route may also explain many other pantropic disjunction patterns, including some Chinese plants disjunctions, involving South America. Not all biogeographical distribution patterns can be explained by vicariance theory, so more research, including chameleon distribution, has recently focused on long-distance dispersal. The lat- est analyses suggest that chameleons have dis- persed over long-distances from Madagascar on several occasions. The floating island model would explain flora and fauna similarities between South America and Africa. Studying long-distance dispersal mechanisms is important for understanding distribu- tion patterns and even the spread of pandemics. More research on the specific implications of long- distance dispersal for biogeography is necessary.展开更多
Dispersals,colonisation,immigration and population assimilation or replacement are fundamental themes in the Palaeolithic record of East Asia.Some of these issues can be studied within a biogeographic framework that e...Dispersals,colonisation,immigration and population assimilation or replacement are fundamental themes in the Palaeolithic record of East Asia.Some of these issues can be studied within a biogeographic framework that explains why and how the distribution of hominin species changed over time and space in response to climatic and environmental change.Because hominins(and especially humans)can change their behaviour through technical,social and cognitive developments,biogeographic models also have to incorporate this factor when investigating dispersals.This is particularly important with the dispersals in East Asia by Homo sapiens into rainforests,across open sea to off-shore islands,to the Arctic and the highest parts of the Tibetan Plateau.This paper suggests how hominin and human dispersals in East Asia might be investigated by using a biogeographic framework that can incorporate changes in hominin adaptability and behaviour.展开更多
Dispersal is an important life history trait with signifcant consequences for spatially structured populations,as the exchange of individuals between habitat patches is crucial for maintaining metapopulation connectiv...Dispersal is an important life history trait with signifcant consequences for spatially structured populations,as the exchange of individuals between habitat patches is crucial for maintaining metapopulation connectivity.In this study,we used a long-term data set(2005–2023)to describe dispersal patterns in a patchy population of the Western Yellow Wagtail Motacilla fava within a large(approximately 1,300 km2)study area in the boreal zone of European Russia.We quantifed dispersal distances for birds that dispersed outside their natal or breeding habitat patches and applied a multistate capture–recapture approach to estimate natal and breeding dispersal probabilities.Of 395 adult wagtails and 1,610 nestlings ringed,3%of birds ringed as adults and 3%of birds ringed as nestlings were resighted outside their natal or breeding patches.The probability of natal dispersal(0.29±0.05)was signifcantly higher than the probability of breeding dispersal(0.05±0.01).The median natal dispersal distances(2.8 km for males,3.9 km for females)were the same as the median breeding dispersal distances(2.7 km for males,3.9 km for females).We did not fnd a signifcant effect of the fedging date on either the natal dispersal distance or the natal dispersal probability.Similarly,we did not fnd a signifcant effect of the previous reproductive success on either the breeding dispersal distance or the breeding dispersal probability.Our results indicate that strong breeding site fdelity and short-distance natal dispersal are the dominant dispersal strategies in a patchy population of the western yellow wagtail.展开更多
This study investigates inductively coupled transmission technology using seawater and underwater anchor chains as the transmission medium for real-time data transfer from underwater measurement instruments.Because of...This study investigates inductively coupled transmission technology using seawater and underwater anchor chains as the transmission medium for real-time data transfer from underwater measurement instruments.Because of the physical properties of seawater,challenges,such as frequency selective fading and multipath effect,limit long-distance current signal transmission.Conventional modulation techniques,such as amplitude shift keying(ASK)and differential phase shift keying(DPSK),are constrained by low bandwidth utilization and high bit error rates(BER).To address these issues,we optimize the seawater channel model using data from the National Oceanographic Data Center and previous measurements,analyzing the relationship between seawater conductivity,depth,and signal frequency.We constructed an experimental platform using a six-winding manganese-zinc ferrite ring based on an inductive coupling model for data transmission.A steel cable is anchored at both ends of a seawater bucket through two rings,exposing the cable core to establish a closed loop in seawater.An orthogonal frequency division multiplexing(OFDM)algorithm is used to improve transmission performance by distributing data across multiple subcarriers,effectively mitigating multipath fading and frequency selective fading.Compared with ASK and DPSK,this method significantly reduces the BER and improves the channel capacity,exhibiting robustness in underwater communication.Finally,in our study,a mathematical model of the underwater multipath channel for distances of 300,1000,and 2000 m is established,showing an improvement in channel capacity of approximately 2.5 bps/Hz based on the OFDM algorithm.This advancement is essential for enhancing the performance of underwater signal transmission and supporting its practical application.展开更多
Natal dispersal is a critical trait for individual ftness and the viability,structure,and genetic identity of populations.However,there is a pronounced information gap for large and long-lived species due to the diffc...Natal dispersal is a critical trait for individual ftness and the viability,structure,and genetic identity of populations.However,there is a pronounced information gap for large and long-lived species due to the diffculty of monitoring individuals at appropriate spatio-temporal scales.Here we study how individual traits and social and environmental characteristics infuence natal dispersal decisions of griffon vultures(Gypsfulvus)using long-term(30 years)monitoring of a large number of individuals marked as nestlings in Spain.Our results show a strong philopatryin both sexes,with some individuals recruiting as breeders on the same cliffs,and even the same nests,where they were born.This philopatrictendency was modulated by the effect of conspecifc density on individual parameters and emphasized the importance of conspecifc attraction and changes in food availability that may have infuenced the increment in colony size and the colonization of new areas.Although furtherresearch is needed considering smaller colonies and more isolated population nuclei,our results highlight the importance of long-term studieson long-lived species to understand the factors that determine their population dynamics and their relationship with anthropogenic activities,whose effects should be predicted and managed using conservation criteria.展开更多
Mimetic seeds attract birds to disperse seeds mainly by mimicking fleshy fruits or arillate seeds,however,they provide little nutritive reward for bird dispersers.The key characteristics of mimetic seeds are conspicuo...Mimetic seeds attract birds to disperse seeds mainly by mimicking fleshy fruits or arillate seeds,however,they provide little nutritive reward for bird dispersers.The key characteristics of mimetic seeds are conspicuous seed color,hard seed coat,certain toxic secondary metabolites,and perhaps smooth waxy layer.In this review,we discuss the global distribution of mimetic seeds,the interaction of mimetic seeds with bird dispersers,and secondary metabolites that underlie key characteristics of mimetic seeds.Mimetic-seed species mainly occur in the tropics,with large numbers distributed along coastal areas.The interaction between mimetic-seed species and bird dispersers can be antagonistic,mutualistic,or both.These interactions are generally established by conspicuous visual cues and hard tactile cues from mimetic seeds.The formation and variation of key characteristics of mimetic seeds may contribute to the metabolism of several kind of secondary compounds.Here,we also discuss mimetic-seed dispersal in the context of an evolutionary game,and propose several aspects of mimetic-seed dispersal that remain unstudied.While this review is based on preliminary findings and does not account for other potential influencing factors such as climate,it is expected to contribute to an improved understanding of mimetic-seed dispersal.展开更多
This paper examines an epidemic predator-prey model with prey dispersal and Holling type-II functional response. In this model, it is assumed that the predator population suffers a transmissible disease. By analyzing ...This paper examines an epidemic predator-prey model with prey dispersal and Holling type-II functional response. In this model, it is assumed that the predator population suffers a transmissible disease. By analyzing the corresponding characteristic equations, the local stability of each of feasible equilibria and the existence of Hopf bifurcations at the coexistence equilibrium is addressed. Using Lyapunov functionals and LaSalle's invariance principle, we obtained the sufficient conditions for the global stability of the trivial equilibrium, the predator-extinction equilibrium, the disease-free equilibrium and the coexistence equilibrium, respectively. The paper also includes numerical simulations to illustrate the analytical results.展开更多
It is well-known that the propagation phenomena of nonlocal dispersal equations have been extensively studied,and the known results on the interface dynamics of this equation are under the compactly supported initial ...It is well-known that the propagation phenomena of nonlocal dispersal equations have been extensively studied,and the known results on the interface dynamics of this equation are under the compactly supported initial value.Moreover,there was no explicit formula regarding the interface due to the peculiarity of nonlocal dispersal operators.Anatural question is whether it is possible to provide a precise characterization of the interface with respect to small parameter for the general initial values(including exponentially bounded and unbounded).This paper is concerned with the interface dynamics of the nonlocal dispersal equation with scaling parameter.For the exponentially bounded initial value,by choosing the hyperbolic scaling,we show that at a very small time,the interface is confined within a generated layer whose thickness is at most O(√ɛ|ln ɛ|),,and subsequently,the interface propagates at a linear speed determined by the decay rate of initial value.For a class of exponentially unbounded initial value,by introducing the nonlinear scaling based on the decay of initial value,we deduce the corresponding Hamilton-Jacobi equation and describe precisely the propagation of the interface,which provides a superlinear speed of the interface.The investigation of the interface dynamics under different scaling reflects multiplex propagation modes in spatial dynamics and provides a new perspective on the wave propagation in nonlocal dispersal equations.展开更多
Elucidating the mechanisms underlying community assembly remains a central question in community ecology,especially in aquatic ecosystems disrupted by human activities.Understanding the causes and consequences of comm...Elucidating the mechanisms underlying community assembly remains a central question in community ecology,especially in aquatic ecosystems disrupted by human activities.Understanding the causes and consequences of community responses to changing environment is essential for revealing the ecological effects of anthropogenic disturbances and proposing practical strategies for ecological restoration.While stochastic dispersal and species sorting are known to influence local biological communities,most studies have focused on horizontal dispersal,often neglecting the vertical exchange of organisms between planktonic and sedimentary communities when studying stochastic dispersal.We used a highly disturbed urban river in Beijing as a model system to investigate the relative roles of stochastic dispersal versus species sorting driven by local pollution,as well as two components of stochastic dispersal,vertical exchange and horizontal dispersal,in structuring local bacterial communities.Our integrated analyses of planktonic and sedimentary bacterial communities revealed that,despite different spatial patterns along the river,both types of bacterial communities were primarily shaped by stochastic dispersal processes rather than species sorting influenced by the environmental gradient.Notably,in addition to the effect of horizontal dispersal along the river,the vertical exchange between planktonic and sedimentary bacterial communities significantly contributed to the formation of local communities.These findings suggest that both vertical exchange and horizontal dispersal should be considered when assessing the role of stochastic dispersal in shaping local community structure in microbial communities.展开更多
A predator-prey model with prey dispersal and Holling type-Ⅱ functional response is investigated.In this model,the time delay due to the gestation of the predator and stagestructure for the predator are considered.By...A predator-prey model with prey dispersal and Holling type-Ⅱ functional response is investigated.In this model,the time delay due to the gestation of the predator and stagestructure for the predator are considered.By analyzing the corresponding characteristic equations,the local stability of each of the nonnegative equilibria is discussed.The existence of Hopf bifurcations at the positive equilibrium is established.By using Lyapunov functionals and LaSalle’s invariance principle,sufficient conditions are obtained for the global stability of the positive equilibrium,the nonnegative boundary equilibrium and the trivial equilibrium of the model,respectively.Numerical simulations are carried out to illustrate the main results.展开更多
To assess the population development of submerged plant species in disturbed lake ecosystems,we need to better understand the genetic diversity and spatial genetic structure at a fine scale,as well as the impact of di...To assess the population development of submerged plant species in disturbed lake ecosystems,we need to better understand the genetic diversity and spatial genetic structure at a fine scale,as well as the impact of disturbances on the populations.Caohai Lake,in southwest China,is a suitable natural sampling lake because of its abundance of submerged plants and the intense human disturbance.Three widely distributed species,Potamogeton lucens,Ceratophyllum demersum,and Myriophyllum spicatum,were sampled;the spatial position of each individual was recorded in two-dimensional coordinates;and the species were analyzed genetically using microsatellite markers.Among the species studied,M.spicatum exhibited the highest genetic and clonal diversities.All P.lucens subpopulations but one showed a significant fine-scale spatial genetic structure(FSGS),which may result from the limited gene dispersal.However,M.spicatum and C.demersum,with a relatively large distance of gene dispersal,had no significant FSGS.The FSGS pattern of P.lucens at the dock site with intense boat disturbance was significantly different from that at other sites.Our results imply that the FSGS of submerged plants is affected by many factors including seed dispersal,vegetative reproduction and disturbance from birds and boats.Most subpopulations of the three species hadσ_(sex)^(2)/σ_(veg)^(2)values greater than one,implying that the sexual dispersal contributes more than vegetative dispersal to total gene dispersal.Therefore,it is worth paying attention to the importance of seed dispersal for population development of submerged plants in lake ecosystems.展开更多
This letter addresses challenges in the clinical translation of BIBR1532,a promising telomerase inhibitor,for the treatment of esophageal squamous cell carcinoma(ESCC).BIBR1532 exerts its anti-cancer effect by activat...This letter addresses challenges in the clinical translation of BIBR1532,a promising telomerase inhibitor,for the treatment of esophageal squamous cell carcinoma(ESCC).BIBR1532 exerts its anti-cancer effect by activating DNA damage response(ATR/CHK1 and ATM/CHK2)pathways and downregulating telomere-binding proteins.Although its therapeutic potential is limited by poor aqueous solubility,solid dispersion(SD)technology may overcome this obstacle.Systematic analysis using PubChem-derived simplified molecular input line entry system identifiers and artificial intelligence-driven FormulationDT platform evaluation(oral formulation feasibility index:0.38)revealed that the SD technology,with superior scalability(32 approved products by 2021)and lower production risks,outperforms lipid-based formulations as an optimal dissolution strategy.Material analysis revealed hydroxypropyl methylcellulose(HPMC)as the optimal carrier with lower hygroscopicity,higher temperature and no intestinal targeting,thus enabling ESCC therapy.HPMC-based SD enhances BIBR1532 solubility and bioavailability for effective ESCC treatment.Future studies should focus on pilot tests for SD fabrication.展开更多
Oxide dispersion strengthened(ODS)alloys are extensively used owing to high thermostability and creep strength contributed from uniformly dispersed fine oxides particles.However,the existence of these strengthening pa...Oxide dispersion strengthened(ODS)alloys are extensively used owing to high thermostability and creep strength contributed from uniformly dispersed fine oxides particles.However,the existence of these strengthening particles also deteriorates the processability and it is of great importance to establish accurate processing maps to guide the thermomechanical processes to enhance the formability.In this study,we performed particle swarm optimization-based back propagation artificial neural network model to predict the high temperature flow behavior of 0.25wt%Al2O3 particle-reinforced Cu alloys,and compared the accuracy with that of derived by Arrhenius-type constitutive model and back propagation artificial neural network model.To train these models,we obtained the raw data by fabricating ODS Cu alloys using the internal oxidation and reduction method,and conducting systematic hot compression tests between 400 and800℃with strain rates of 10^(-2)-10 S^(-1).At last,processing maps for ODS Cu alloys were proposed by combining processing parameters,mechanical behavior,microstructure characterization,and the modeling results achieved a coefficient of determination higher than>99%.展开更多
Aim To study fuel dispersion in fuel air explosive(FAE) and computational ways of fuel dispersion velocity in the near area. Methods\ The dispersion process of fuel in FAE was analyzed by the use of results measured ...Aim To study fuel dispersion in fuel air explosive(FAE) and computational ways of fuel dispersion velocity in the near area. Methods\ The dispersion process of fuel in FAE was analyzed by the use of results measured with KODAK EKTAPRO EM Motion Analyzer and setting up mechanical models. Results\ Computational methods for fuel dispersion velocity in the acceleration stage is given and taken as a base for the study of fuel dispersion in the intermediate and the far area. Conclusion\ When the fuel flow velocity is higher than that of the explosion gas in the center cavity, the fuel divides with the explosion gas and its velocity of flow reaches a maximum. The acceleration stage ends at that time. The fuel dispersion velocity at this time is the initial conditions for numeral analyses of dispersion process in the intermediate and far areas.展开更多
基金funded equally by grants from the National Natural Science Foundation of China(32322006 and 32100187)the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(2024QZKK0200)+5 种基金by the Key Projects of the Joint Fund of the National Natural Science Foundation of China(U23A20149)the Key R&D Program of Yunnan Province(202103AF140005 and 202101BC070002)the Yunnan Provincial Science and Technology Talent and Platform Plan(202305AM070005)the Key Specialized Research and Development Breakthrough Program in Henan Province(232102110237)the Natural Science Foundation of Henan Province(242300421572)the Strategic Biological Resources Capacity Building Project of Chinese Academy of Sciences(KFJ-BRP-017-08).
文摘The formation of pantropical intercontinental disjunction(PID)in plants has generally been attributed to vicariance,boreotropical migration,and long-distance dispersal.However,this pattern has primarily been examined in herbs,shrubs,and trees,and less commonly studied in interlayer plant taxa.Here we examined evolutionary processes that resulted in the PID of a pantropical woody liana,Uncaria(Rubiaceae).We first constructed a comprehensive phylogeny by employing 73 plastid protein-coding sequences from 29 accessions of Uncaria(including 16 newly sequenced)from different continents.We then inferred divergence time,history and ecological niche evolution of this genus.Our results showed that Uncaria consisted of four well-supported clades that belonged to two geographically distinct lineages:the Asia-Oceania lineage and the Afro-Neotropical lineage.Biogeographic reconstruction showed this genus likely originated in Asia during the early Miocene(ca.19.03 Ma)and the Middle Miocene Climatic Optimum may have triggered the early diversification of Uncaria.Due to its recent origin and small seeds with long wings,wind or water-mediated long-distance dispersal may have contributed to the distribution of Uncaria in tropical Oceania(via stepping-stone dispersal)and tropical Africa and America(by transoceanic dispersal).Our findings also indicate that diversification of Uncaria was primarily driven by ecological niche divergence,particularly climatic factors.Our study emphasizes the dual role of climatic niche divergence and long-distance dispersal in shaping the PID of Uncaria,providing references for many other extant lineages with similar distributions.
基金National Natural Science Foundation of China(No.31300526)National Key Technologies R&D Program of China(No.2012BAD22B04)Chinese Forest Ecosystem Research Network&GENE Award Funds on Ecological Paper
文摘Seed long-distance dispersal(LDD) events are typically rare, but are important in the population processes that determine large-scale forest changes and the persistence of species in fragmented landscapes. However, previous studies focused on species dispersed via animal-mediated LDD, and ignored those dispersed by wind. The aim of this study was to assess the effects of canopy openness, edge, seed source, and patch tree density on the LDD of seeds by wind in forest. We collected birch seeds, a typical wind-dispersed species, throughout a larch plantation. We then assessed the relationship between birch LDD and each factor that may influence LDD of seeds by wind including distance to edge, canopy openness size, distance to mature forest, and the tree density of the larch plantation. We used univariate linear regression analysis to assess the influence of those factors on birch LDD, and partial correlations to calculate the contribution of each factor to LDD. The results showed that both canopy openness and edge had significant influences on birch LDD. Specifically, a negative relationship was observed between distance to edge and birch LDD, whereas there was a positive correlation between canopy openness size and LDD. In contrast, the distance to the mature forest was not correlated with birch LDD. Our results suggest that patch tree density could potently affect the probability of LDD by wind vectors, which provides novel and revealing insights regarding the effect of fragmentation on wind dynamics. The data also provide compelling evidence for the previously undocumented effect of habitat fragmentation on wind-dispersed organisms. As such, these observations will facilitate reasonable conservation planning, which requires a detailed understanding of the mechanisms by which patch properties hamper the delivery of seeds of wind-dispersed plants to fragmented areas.
文摘The relative contribution of long-distance dispersal and local diffusion in the spread of invasive species has been a subject of much debate. Invasion of the intertidal mudflats by Spartina alterniflora is an ideal example of stratified diffusion, involving both long-distance dispersal of seeds and local diffusion due to clonal growth. In conjunction with experimental data on range radius-versus-time curve, a traveling wave equation-based model is used to investigate the sensitivity of the spread rate of exotic S. alterniflora to parameters of long distance dispersal (c, maximum colonial establishment rate) and local colony diffusion (r, intrinsic growth rate) at two tidal marshes, the Eastern Chongming and the Jiuduansha Islands, at the Yangtze River estuary. Both Eastern Chong ming and Jiuduansha Islands are now national natural reserves in China, which were established in 2005. However, the mudflats and salt marshes in the two reserves are now heavily infested with introduced S. alterniflora, which may threaten the estuarine ecosystems and their biodiversity. S. alterniflora was first found in 1995 on Chongming. For rapid sediment accretion in mudflats in the estuary, S. alterniflora was also intentionally introduced to Jiuduansha in 1997 and Chongming in 2001, which has led to a rapid range expansion in the estuary. Our results show that range expansion of species with stratified diffusion is affected by both long-distance dispersal and local colony diffusion, and that there is a critical c*, below which the spread rate is more influenced by long-distance dispersal than by local diffusion. After applying this model to the invasion of S. alterniflora in the Yangtze River estuary, we derive that c = 1.7 × 10-3, c* = 0.126 and c = 4.8 × 10-3 km-2·yr-1, c* = 0.140 km-2·yr-1 at Chongming and Jiuduansha (Shanghai), respectively. Our results suggest that the range spread of S. alterniflora in the Yangtze River estuary is more influenced by long-distance dispersal than local colony diffusion, and that S. alterniflora generates about 1.7 × 10-3 to 4.8 × 10-3 colonies per square kilometers per year. This study provides important information about dispersal dynamics of S. alterniflora that may be useful for finding optimal control strategies. ·
基金This work was jointly supported by the National Key Basic Research Program （973） （Grant No. 2003CB415102） the National Natural Science Foundation of China （Grants Nos. 40332021 ＆ 30540077）the Yunnan Provincial Govern- ment through an Award for Prominent Contributions in Science and Technology to Prof. Wu Zhengyi in 2001 （Grant No. KIB-WU-2001-01）.
文摘The study of land bridge based on con- tinental drift1) and long-distance dispersal are gaining increasing attention in biogeography. We review several major dispersal theories including the Mal- pigiacea route, patterns of chameleon dispersal and the floating island model. The Malpigiaceae route indicates that the Malpigiaceae family originated in northern South America and that members of several clades migrated into North America and subsequently moved via north Atlantic land connections into the Old World starting in the Eocene. This route may also explain many other pantropic disjunction patterns, including some Chinese plants disjunctions, involving South America. Not all biogeographical distribution patterns can be explained by vicariance theory, so more research, including chameleon distribution, has recently focused on long-distance dispersal. The lat- est analyses suggest that chameleons have dis- persed over long-distances from Madagascar on several occasions. The floating island model would explain flora and fauna similarities between South America and Africa. Studying long-distance dispersal mechanisms is important for understanding distribu- tion patterns and even the spread of pandemics. More research on the specific implications of long- distance dispersal for biogeography is necessary.
文摘Dispersals,colonisation,immigration and population assimilation or replacement are fundamental themes in the Palaeolithic record of East Asia.Some of these issues can be studied within a biogeographic framework that explains why and how the distribution of hominin species changed over time and space in response to climatic and environmental change.Because hominins(and especially humans)can change their behaviour through technical,social and cognitive developments,biogeographic models also have to incorporate this factor when investigating dispersals.This is particularly important with the dispersals in East Asia by Homo sapiens into rainforests,across open sea to off-shore islands,to the Arctic and the highest parts of the Tibetan Plateau.This paper suggests how hominin and human dispersals in East Asia might be investigated by using a biogeographic framework that can incorporate changes in hominin adaptability and behaviour.
基金supported by the Russian Science Foundation(grant number 23-24-00042).
文摘Dispersal is an important life history trait with signifcant consequences for spatially structured populations,as the exchange of individuals between habitat patches is crucial for maintaining metapopulation connectivity.In this study,we used a long-term data set(2005–2023)to describe dispersal patterns in a patchy population of the Western Yellow Wagtail Motacilla fava within a large(approximately 1,300 km2)study area in the boreal zone of European Russia.We quantifed dispersal distances for birds that dispersed outside their natal or breeding habitat patches and applied a multistate capture–recapture approach to estimate natal and breeding dispersal probabilities.Of 395 adult wagtails and 1,610 nestlings ringed,3%of birds ringed as adults and 3%of birds ringed as nestlings were resighted outside their natal or breeding patches.The probability of natal dispersal(0.29±0.05)was signifcantly higher than the probability of breeding dispersal(0.05±0.01).The median natal dispersal distances(2.8 km for males,3.9 km for females)were the same as the median breeding dispersal distances(2.7 km for males,3.9 km for females).We did not fnd a signifcant effect of the fedging date on either the natal dispersal distance or the natal dispersal probability.Similarly,we did not fnd a signifcant effect of the previous reproductive success on either the breeding dispersal distance or the breeding dispersal probability.Our results indicate that strong breeding site fdelity and short-distance natal dispersal are the dominant dispersal strategies in a patchy population of the western yellow wagtail.
基金supported by grants from the National Natural Science Foundation of China(No.62071329)the National Science Foundation of Tianjin(No.23JCZDJC00440)the Key Areas R&D Programs of Guangdong Province(No.2020B1111020001).
文摘This study investigates inductively coupled transmission technology using seawater and underwater anchor chains as the transmission medium for real-time data transfer from underwater measurement instruments.Because of the physical properties of seawater,challenges,such as frequency selective fading and multipath effect,limit long-distance current signal transmission.Conventional modulation techniques,such as amplitude shift keying(ASK)and differential phase shift keying(DPSK),are constrained by low bandwidth utilization and high bit error rates(BER).To address these issues,we optimize the seawater channel model using data from the National Oceanographic Data Center and previous measurements,analyzing the relationship between seawater conductivity,depth,and signal frequency.We constructed an experimental platform using a six-winding manganese-zinc ferrite ring based on an inductive coupling model for data transmission.A steel cable is anchored at both ends of a seawater bucket through two rings,exposing the cable core to establish a closed loop in seawater.An orthogonal frequency division multiplexing(OFDM)algorithm is used to improve transmission performance by distributing data across multiple subcarriers,effectively mitigating multipath fading and frequency selective fading.Compared with ASK and DPSK,this method significantly reduces the BER and improves the channel capacity,exhibiting robustness in underwater communication.Finally,in our study,a mathematical model of the underwater multipath channel for distances of 300,1000,and 2000 m is established,showing an improvement in channel capacity of approximately 2.5 bps/Hz based on the OFDM algorithm.This advancement is essential for enhancing the performance of underwater signal transmission and supporting its practical application.
基金partially funded through projects PID2019-109685GB-I00,CGL2007-61395,CGL2010-15726,and CGL2013-42451-P,of the Spanish Ministry of Science and Innovation.
文摘Natal dispersal is a critical trait for individual ftness and the viability,structure,and genetic identity of populations.However,there is a pronounced information gap for large and long-lived species due to the diffculty of monitoring individuals at appropriate spatio-temporal scales.Here we study how individual traits and social and environmental characteristics infuence natal dispersal decisions of griffon vultures(Gypsfulvus)using long-term(30 years)monitoring of a large number of individuals marked as nestlings in Spain.Our results show a strong philopatryin both sexes,with some individuals recruiting as breeders on the same cliffs,and even the same nests,where they were born.This philopatrictendency was modulated by the effect of conspecifc density on individual parameters and emphasized the importance of conspecifc attraction and changes in food availability that may have infuenced the increment in colony size and the colonization of new areas.Although furtherresearch is needed considering smaller colonies and more isolated population nuclei,our results highlight the importance of long-term studieson long-lived species to understand the factors that determine their population dynamics and their relationship with anthropogenic activities,whose effects should be predicted and managed using conservation criteria.
基金supported by the Yunnan Ten Thousand Talents Plan Young&Elite Talents Project(YNWR-QNBJ-2018-017)the National Natural Science Foundation of China(32371564)+2 种基金the Key Project of Basic Research of Yunnan Province,China(202101AS070035202301AS070001)to G.ChenYunnan Provincial Science and Technology Talent and Platform Plan(202305AM070005).
文摘Mimetic seeds attract birds to disperse seeds mainly by mimicking fleshy fruits or arillate seeds,however,they provide little nutritive reward for bird dispersers.The key characteristics of mimetic seeds are conspicuous seed color,hard seed coat,certain toxic secondary metabolites,and perhaps smooth waxy layer.In this review,we discuss the global distribution of mimetic seeds,the interaction of mimetic seeds with bird dispersers,and secondary metabolites that underlie key characteristics of mimetic seeds.Mimetic-seed species mainly occur in the tropics,with large numbers distributed along coastal areas.The interaction between mimetic-seed species and bird dispersers can be antagonistic,mutualistic,or both.These interactions are generally established by conspicuous visual cues and hard tactile cues from mimetic seeds.The formation and variation of key characteristics of mimetic seeds may contribute to the metabolism of several kind of secondary compounds.Here,we also discuss mimetic-seed dispersal in the context of an evolutionary game,and propose several aspects of mimetic-seed dispersal that remain unstudied.While this review is based on preliminary findings and does not account for other potential influencing factors such as climate,it is expected to contribute to an improved understanding of mimetic-seed dispersal.
基金Supported by the Social Science Foundation of Hebei Province(Grant No.HB23TJ003)the Science Research Project of Hebei Education Department(Grant No.BJK2024197)。
文摘This paper examines an epidemic predator-prey model with prey dispersal and Holling type-II functional response. In this model, it is assumed that the predator population suffers a transmissible disease. By analyzing the corresponding characteristic equations, the local stability of each of feasible equilibria and the existence of Hopf bifurcations at the coexistence equilibrium is addressed. Using Lyapunov functionals and LaSalle's invariance principle, we obtained the sufficient conditions for the global stability of the trivial equilibrium, the predator-extinction equilibrium, the disease-free equilibrium and the coexistence equilibrium, respectively. The paper also includes numerical simulations to illustrate the analytical results.
基金partially supported by the NSF of China(12271226)partially supported by the NSF of China(12201434)+4 种基金the NSF of Gansu Province of China(21JR7RA537)the NSF of Gansu Province of China(21JR7RA535)the Fundamental Research Funds for the Central Universities(lzujbky-2021-kb15)partially supported by the NSF of China(12371170)the R&D Program of Beijing Municipal Education Commission(KM202310028017)。
文摘It is well-known that the propagation phenomena of nonlocal dispersal equations have been extensively studied,and the known results on the interface dynamics of this equation are under the compactly supported initial value.Moreover,there was no explicit formula regarding the interface due to the peculiarity of nonlocal dispersal operators.Anatural question is whether it is possible to provide a precise characterization of the interface with respect to small parameter for the general initial values(including exponentially bounded and unbounded).This paper is concerned with the interface dynamics of the nonlocal dispersal equation with scaling parameter.For the exponentially bounded initial value,by choosing the hyperbolic scaling,we show that at a very small time,the interface is confined within a generated layer whose thickness is at most O(√ɛ|ln ɛ|),,and subsequently,the interface propagates at a linear speed determined by the decay rate of initial value.For a class of exponentially unbounded initial value,by introducing the nonlinear scaling based on the decay of initial value,we deduce the corresponding Hamilton-Jacobi equation and describe precisely the propagation of the interface,which provides a superlinear speed of the interface.The investigation of the interface dynamics under different scaling reflects multiplex propagation modes in spatial dynamics and provides a new perspective on the wave propagation in nonlocal dispersal equations.
基金supported by the National Natural Science Foundation of China(No.32471608)the Open Project of Key Laboratory of Environmental Biotechnology,CAS(No.kf2020002)Yunnan Collaborative Innovation Center for Plateau Lake Ecology and Environmental Health.
文摘Elucidating the mechanisms underlying community assembly remains a central question in community ecology,especially in aquatic ecosystems disrupted by human activities.Understanding the causes and consequences of community responses to changing environment is essential for revealing the ecological effects of anthropogenic disturbances and proposing practical strategies for ecological restoration.While stochastic dispersal and species sorting are known to influence local biological communities,most studies have focused on horizontal dispersal,often neglecting the vertical exchange of organisms between planktonic and sedimentary communities when studying stochastic dispersal.We used a highly disturbed urban river in Beijing as a model system to investigate the relative roles of stochastic dispersal versus species sorting driven by local pollution,as well as two components of stochastic dispersal,vertical exchange and horizontal dispersal,in structuring local bacterial communities.Our integrated analyses of planktonic and sedimentary bacterial communities revealed that,despite different spatial patterns along the river,both types of bacterial communities were primarily shaped by stochastic dispersal processes rather than species sorting influenced by the environmental gradient.Notably,in addition to the effect of horizontal dispersal along the river,the vertical exchange between planktonic and sedimentary bacterial communities significantly contributed to the formation of local communities.These findings suggest that both vertical exchange and horizontal dispersal should be considered when assessing the role of stochastic dispersal in shaping local community structure in microbial communities.
基金Supported by the Social Science Foundation of Hebei Province(HB23TJO03)。
文摘A predator-prey model with prey dispersal and Holling type-Ⅱ functional response is investigated.In this model,the time delay due to the gestation of the predator and stagestructure for the predator are considered.By analyzing the corresponding characteristic equations,the local stability of each of the nonnegative equilibria is discussed.The existence of Hopf bifurcations at the positive equilibrium is established.By using Lyapunov functionals and LaSalle’s invariance principle,sufficient conditions are obtained for the global stability of the positive equilibrium,the nonnegative boundary equilibrium and the trivial equilibrium of the model,respectively.Numerical simulations are carried out to illustrate the main results.
基金Supported by the National Natural Science Foundation of China(No.31600325)the Self-determined Research Funds of the Central China Normal University(CCNU)from the Colleges’Basic Research and Operation of MOE(No.CCNU20TS022)。
文摘To assess the population development of submerged plant species in disturbed lake ecosystems,we need to better understand the genetic diversity and spatial genetic structure at a fine scale,as well as the impact of disturbances on the populations.Caohai Lake,in southwest China,is a suitable natural sampling lake because of its abundance of submerged plants and the intense human disturbance.Three widely distributed species,Potamogeton lucens,Ceratophyllum demersum,and Myriophyllum spicatum,were sampled;the spatial position of each individual was recorded in two-dimensional coordinates;and the species were analyzed genetically using microsatellite markers.Among the species studied,M.spicatum exhibited the highest genetic and clonal diversities.All P.lucens subpopulations but one showed a significant fine-scale spatial genetic structure(FSGS),which may result from the limited gene dispersal.However,M.spicatum and C.demersum,with a relatively large distance of gene dispersal,had no significant FSGS.The FSGS pattern of P.lucens at the dock site with intense boat disturbance was significantly different from that at other sites.Our results imply that the FSGS of submerged plants is affected by many factors including seed dispersal,vegetative reproduction and disturbance from birds and boats.Most subpopulations of the three species hadσ_(sex)^(2)/σ_(veg)^(2)values greater than one,implying that the sexual dispersal contributes more than vegetative dispersal to total gene dispersal.Therefore,it is worth paying attention to the importance of seed dispersal for population development of submerged plants in lake ecosystems.
基金Supported by“Continuation”Project of Excellent Doctors,Guangdong Basic and Applied Basic Research Foundation,No.2025A04J5082Guangdong Basic and Applied Basic Research Foundation,No.2024A1515011236.
文摘This letter addresses challenges in the clinical translation of BIBR1532,a promising telomerase inhibitor,for the treatment of esophageal squamous cell carcinoma(ESCC).BIBR1532 exerts its anti-cancer effect by activating DNA damage response(ATR/CHK1 and ATM/CHK2)pathways and downregulating telomere-binding proteins.Although its therapeutic potential is limited by poor aqueous solubility,solid dispersion(SD)technology may overcome this obstacle.Systematic analysis using PubChem-derived simplified molecular input line entry system identifiers and artificial intelligence-driven FormulationDT platform evaluation(oral formulation feasibility index:0.38)revealed that the SD technology,with superior scalability(32 approved products by 2021)and lower production risks,outperforms lipid-based formulations as an optimal dissolution strategy.Material analysis revealed hydroxypropyl methylcellulose(HPMC)as the optimal carrier with lower hygroscopicity,higher temperature and no intestinal targeting,thus enabling ESCC therapy.HPMC-based SD enhances BIBR1532 solubility and bioavailability for effective ESCC treatment.Future studies should focus on pilot tests for SD fabrication.
基金financial support of the National Natural Science Foundation of China(No.52371103)the Fundamental Research Funds for the Central Universities,China(No.2242023K40028)+1 种基金the Open Research Fund of Jiangsu Key Laboratory for Advanced Metallic Materials,China(No.AMM2023B01).financial support of the Research Fund of Shihezi Key Laboratory of AluminumBased Advanced Materials,China(No.2023PT02)financial support of Guangdong Province Science and Technology Major Project,China(No.2021B0301030005)。
文摘Oxide dispersion strengthened(ODS)alloys are extensively used owing to high thermostability and creep strength contributed from uniformly dispersed fine oxides particles.However,the existence of these strengthening particles also deteriorates the processability and it is of great importance to establish accurate processing maps to guide the thermomechanical processes to enhance the formability.In this study,we performed particle swarm optimization-based back propagation artificial neural network model to predict the high temperature flow behavior of 0.25wt%Al2O3 particle-reinforced Cu alloys,and compared the accuracy with that of derived by Arrhenius-type constitutive model and back propagation artificial neural network model.To train these models,we obtained the raw data by fabricating ODS Cu alloys using the internal oxidation and reduction method,and conducting systematic hot compression tests between 400 and800℃with strain rates of 10^(-2)-10 S^(-1).At last,processing maps for ODS Cu alloys were proposed by combining processing parameters,mechanical behavior,microstructure characterization,and the modeling results achieved a coefficient of determination higher than>99%.
文摘Aim To study fuel dispersion in fuel air explosive(FAE) and computational ways of fuel dispersion velocity in the near area. Methods\ The dispersion process of fuel in FAE was analyzed by the use of results measured with KODAK EKTAPRO EM Motion Analyzer and setting up mechanical models. Results\ Computational methods for fuel dispersion velocity in the acceleration stage is given and taken as a base for the study of fuel dispersion in the intermediate and the far area. Conclusion\ When the fuel flow velocity is higher than that of the explosion gas in the center cavity, the fuel divides with the explosion gas and its velocity of flow reaches a maximum. The acceleration stage ends at that time. The fuel dispersion velocity at this time is the initial conditions for numeral analyses of dispersion process in the intermediate and far areas.
