Works concerning zooplankton of freshwaters of the western area of Algeria are only very fragmentary and remain at an embryonic state. Remediating to this situation, it led a study of the biodiversity and zooplanktoni...Works concerning zooplankton of freshwaters of the western area of Algeria are only very fragmentary and remain at an embryonic state. Remediating to this situation, it led a study of the biodiversity and zooplanktonic populations distribution in time and space in the Boughrara dam lake which remains subject to a strong pollution coming essentially from Morocco. The preliminary results of the faunistic analysis of the zooplanktonic populations enabled to highlight an important richness of zoological groups. The CFA （correspondences factorial analysis） and the AHC （ascending hierarchical classification） methods used both enabled to define the species distribution of both open waters and littoral ones, and also to perform existing affinities between them and the state of the used medium. Compared to other barrages, such as those of Bouhanifia and of Sarno, the zooplanktonic populations of both open waters and littoral populations appear to a great extent numerous in rain period. On the quantitative and qualitative level, the zooplanktonic populations strongly suffer from the pollution contamination coming from the Mouillah River especially in summer period. It is time to think about the protection of this fauna which is the second trophic chain link and this intending to preserve the ecosystems in an equilibrium state and to consider the exploitation of natural resources in the realization of an aquacultural farm.展开更多
When facilitating other species and sustaining plant community structures and biodiversity,alpine cushion plants simultaneously experience negative feedback effects from surrounding vegetation.However,the impact of su...When facilitating other species and sustaining plant community structures and biodiversity,alpine cushion plants simultaneously experience negative feedback effects from surrounding vegetation.However,the impact of surrounding vegetation on cushion dynamics remains poorly understood,particularly in terms of allelopathic potentials.To investigate the allelopathic potentials of surrounding vegetation on seedling establishment of the typical cushion plant Arenaria polytrichoides Edgew.along an elevational gradient,we extracted potential allelopathic compounds and tested their impacts on seed germination and seedling growth of A.polytrichoides.In addition,exclusion experiments using activated carbon were conducted to further elucidate these effects.Our results demonstrate that surrounding vegetation exhibits certain allelopathic potentials on A.polytrichoides seedling establishment,with variations observed based on elevation,source and concentration of allelopathy compounds,as well as growing season.Specifcally,low-elevation vegetation exerts pronounced suppression on seedling establishment.Conversely,higher-elevation vegetation generally shows no effect on seed germination but stimulates seedling growth through allelopathy mechanisms.Moreover,aboveground vegetation predominantly inhibits both seed germination and seedling growth in low-elevation communities;however,the effects of belowground vegetation depend on elevation and extract concentration levels.The identifed allelopathic potentials of surrounding vegetation signifcantly infuence the population dynamics of cushion A.polytrichoides by potentially accelerating population degeneration in lower-elevation communities while ensuring consistent population recruitment and expansion in higher-elevation communities.展开更多
In this paper, a pest control model with state-dependent impulses is firstly established, which relies on releasing of natural enemies, together with spraying pesticides. By using the successor function of differentia...In this paper, a pest control model with state-dependent impulses is firstly established, which relies on releasing of natural enemies, together with spraying pesticides. By using the successor function of differential equation geometry rules, the existence of order one periodic solution is discussed. According to the Analogue of Poincare＇s Criterion, the orbitally asymptotic stability of the order one periodic solution is obtained. Furthermore, we investigated the global attractor of the system. From a biological point of view, our results indicate that： （1） the pest population can be controlled below some threshold; （2） compared to single measure, it is more efficient to take two measures for reducing the level of the pests.展开更多
Understanding how population sizes vary over time is a key aspect of ecological research. Unfortunately, our under- standing of population dynamics has historically been based on an assumption that individuals are ide...Understanding how population sizes vary over time is a key aspect of ecological research. Unfortunately, our under- standing of population dynamics has historically been based on an assumption that individuals are identical with homogenous life-history properties. This assumption is certainly false for most natural systems, raising the question of what role individual variation plays in the dynamics of populations. While there has been an increase of interest regarding the effects of within popula- tion variation on the dynamics of single populations, there has been little study of the effects of differences in within population variation on patterns observed across populations. We found that life-history differences （clutch size） among individuals ex- plained the majority of the variation observed in the degree to which population sizes of eastern fence lizards Sceloporus undula- tus fluctuated. This finding suggests that differences across populations cannot be understood without an examination of differences at the level of a system rather than at the level of the individual展开更多
This paper deals with the existence of traveling wave solutions in a three-species food-chain model with spatial diffusion and time delays due to gestation and negative feedback. By using a cross iteration scheme and ...This paper deals with the existence of traveling wave solutions in a three-species food-chain model with spatial diffusion and time delays due to gestation and negative feedback. By using a cross iteration scheme and Schauder＇s fixed point theorem, we reduce the existence of traveling wave solutions to the existence of a pair of upper-lower solutions. By constructing a pair of upper-lower solutions, we derive the existence of a traveling wave solution connecting the trivial steady state and the positive steady state. Numerical simulations are carried out to illustrate the main results. In particular, our results extend and improve some known results.展开更多
We study cavity optomechanics of ultracold dual-species atomic mixtures with nonlinear collisions.Interspecies interactions provide a direct parametric coupling of fictitious mechanical elements which,through interfer...We study cavity optomechanics of ultracold dual-species atomic mixtures with nonlinear collisions.Interspecies interactions provide a direct parametric coupling of fictitious mechanical elements which,through interfering with the intracavity optical field,leads to a switchable optically-dark state for either species.This demonstrates a matterwave analog of recently observed mechanical wave mixing and quantum motional-state swapping,with applications in the construction of integrated phononic devices,and the cavity-enhanced detection of quantum degenerate atomic mixtures.展开更多
文摘Works concerning zooplankton of freshwaters of the western area of Algeria are only very fragmentary and remain at an embryonic state. Remediating to this situation, it led a study of the biodiversity and zooplanktonic populations distribution in time and space in the Boughrara dam lake which remains subject to a strong pollution coming essentially from Morocco. The preliminary results of the faunistic analysis of the zooplanktonic populations enabled to highlight an important richness of zoological groups. The CFA （correspondences factorial analysis） and the AHC （ascending hierarchical classification） methods used both enabled to define the species distribution of both open waters and littoral ones, and also to perform existing affinities between them and the state of the used medium. Compared to other barrages, such as those of Bouhanifia and of Sarno, the zooplanktonic populations of both open waters and littoral populations appear to a great extent numerous in rain period. On the quantitative and qualitative level, the zooplanktonic populations strongly suffer from the pollution contamination coming from the Mouillah River especially in summer period. It is time to think about the protection of this fauna which is the second trophic chain link and this intending to preserve the ecosystems in an equilibrium state and to consider the exploitation of natural resources in the realization of an aquacultural farm.
基金supported by the Second Tibetan Plateau Scientifc Expedition and Research Program(2019QZKK0502)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20050203)+1 种基金the Yunnan Applied Basic Research Project(202001AT070060,202301AS070058)the Young Academic and Technical Leader Raising Foundation of Yunnan Province(202205AC160053)。
文摘When facilitating other species and sustaining plant community structures and biodiversity,alpine cushion plants simultaneously experience negative feedback effects from surrounding vegetation.However,the impact of surrounding vegetation on cushion dynamics remains poorly understood,particularly in terms of allelopathic potentials.To investigate the allelopathic potentials of surrounding vegetation on seedling establishment of the typical cushion plant Arenaria polytrichoides Edgew.along an elevational gradient,we extracted potential allelopathic compounds and tested their impacts on seed germination and seedling growth of A.polytrichoides.In addition,exclusion experiments using activated carbon were conducted to further elucidate these effects.Our results demonstrate that surrounding vegetation exhibits certain allelopathic potentials on A.polytrichoides seedling establishment,with variations observed based on elevation,source and concentration of allelopathy compounds,as well as growing season.Specifcally,low-elevation vegetation exerts pronounced suppression on seedling establishment.Conversely,higher-elevation vegetation generally shows no effect on seed germination but stimulates seedling growth through allelopathy mechanisms.Moreover,aboveground vegetation predominantly inhibits both seed germination and seedling growth in low-elevation communities;however,the effects of belowground vegetation depend on elevation and extract concentration levels.The identifed allelopathic potentials of surrounding vegetation signifcantly infuence the population dynamics of cushion A.polytrichoides by potentially accelerating population degeneration in lower-elevation communities while ensuring consistent population recruitment and expansion in higher-elevation communities.
基金Research is supported by the National Natural Science Foundation of China （11271260）, Shanghai Leading Academic Discipline Project （No. XTKX2012）, the Hujiang Foundation of China （B14005） and the Innovation Program of Shanghai Municipal Education Committee （13ZZ116）.
文摘In this paper, a pest control model with state-dependent impulses is firstly established, which relies on releasing of natural enemies, together with spraying pesticides. By using the successor function of differential equation geometry rules, the existence of order one periodic solution is discussed. According to the Analogue of Poincare＇s Criterion, the orbitally asymptotic stability of the order one periodic solution is obtained. Furthermore, we investigated the global attractor of the system. From a biological point of view, our results indicate that： （1） the pest population can be controlled below some threshold; （2） compared to single measure, it is more efficient to take two measures for reducing the level of the pests.
文摘Understanding how population sizes vary over time is a key aspect of ecological research. Unfortunately, our under- standing of population dynamics has historically been based on an assumption that individuals are identical with homogenous life-history properties. This assumption is certainly false for most natural systems, raising the question of what role individual variation plays in the dynamics of populations. While there has been an increase of interest regarding the effects of within popula- tion variation on the dynamics of single populations, there has been little study of the effects of differences in within population variation on patterns observed across populations. We found that life-history differences （clutch size） among individuals ex- plained the majority of the variation observed in the degree to which population sizes of eastern fence lizards Sceloporus undula- tus fluctuated. This finding suggests that differences across populations cannot be understood without an examination of differences at the level of a system rather than at the level of the individual
文摘This paper deals with the existence of traveling wave solutions in a three-species food-chain model with spatial diffusion and time delays due to gestation and negative feedback. By using a cross iteration scheme and Schauder＇s fixed point theorem, we reduce the existence of traveling wave solutions to the existence of a pair of upper-lower solutions. By constructing a pair of upper-lower solutions, we derive the existence of a traveling wave solution connecting the trivial steady state and the positive steady state. Numerical simulations are carried out to illustrate the main results. In particular, our results extend and improve some known results.
基金Supports of the National Natural Science Foundation of China under Grant No. 10974045the Fok Y-T Education Foundation,and the Henan Chuangxin Program
文摘We study cavity optomechanics of ultracold dual-species atomic mixtures with nonlinear collisions.Interspecies interactions provide a direct parametric coupling of fictitious mechanical elements which,through interfering with the intracavity optical field,leads to a switchable optically-dark state for either species.This demonstrates a matterwave analog of recently observed mechanical wave mixing and quantum motional-state swapping,with applications in the construction of integrated phononic devices,and the cavity-enhanced detection of quantum degenerate atomic mixtures.
