We investigate the stochastic resonance (SR) phenomenon induced by the periodic signal in a metapopulation system with colored noises. The analytical expression of signal-to-noise is derived in the adiabatic limit. ...We investigate the stochastic resonance (SR) phenomenon induced by the periodic signal in a metapopulation system with colored noises. The analytical expression of signal-to-noise is derived in the adiabatic limit. By numerical calculation, the effects of the addictive noise intensity, the multiplicative noise intensity and two noise self-correlation times on SNR are respectively discussed. It shows that: (i) in the case that the addictive noise intensity M takes a small value, a SR phenomenon for the curve of SNR appears; however, when M takes a large value, SNR turns into a monotonic function on the multiplicative noise intensity Q. (ii) The resonance peaks in the plots of the multiplicative noise intensity Q versus its self-correlation time Vl and the addictive noise intensity M versus its self-correlation time ~2 translate in parallel. Mean- while, a parallel translation also appears in the plots of vl versus Q and v2 versus M. (iii) The interactive effects between self-correlation times Vl and v2 are opposite.展开更多
Hydrobiidae is one of the most diverse taxa among limnic and estuarine mollusks. Patterns of spatial and seasonal distribution of Heleobia australis were studied in ten stations over two years, in the urban eutrophic ...Hydrobiidae is one of the most diverse taxa among limnic and estuarine mollusks. Patterns of spatial and seasonal distribution of Heleobia australis were studied in ten stations over two years, in the urban eutrophic bay of Guanabara, Rio de Janeiro, Brazil. Spatial dispersal strategies in adults of this species, analyzed in the laboratory, revealed three patterns: 1) mobility on soft sediments;2) mobility on hard substrata;and 3) the ability to lift from the bottom to the surface, to again sink down. This facilitate species movement from one location to another by surface currents or attached to floating debris. Thus, individuals are able to escape from an impacted area and further re-colonize other patches after recovering from local impacts. The hypothesis of metapopulation dynamics (source– sink) was analyzed. Two stations with high and constant numbers of individuals were grouped and tested as possible ‘sources’. The number of specimens in the remaining stations was highly variable, even with the complete disappearance and posterior highly dense re-occurrence of the mollusk, whereby these were tested as possible ‘sinks’. Results derived from nested ANOVA supported the hypothesis of metapopulation dynamics in the case of H. australis adults, ex-pressed through opportunistic-species domi- nation of a highly impacted estuarine system, such as Guanabara Bay.展开更多
Objective: To verify phylogeography and genetic structure of Acanthamoeba populations among the Iranian clinical isolates and natural/artificial environments distributed in various regions of the country.Methods: We s...Objective: To verify phylogeography and genetic structure of Acanthamoeba populations among the Iranian clinical isolates and natural/artificial environments distributed in various regions of the country.Methods: We searched electronic databases including Medline, Pub Med, Science Direct, Scopus and Google Scholar from 2005 to 2016. To explore the genetic variability of Acanthamoeba sp, 205 sequences were retrieved from keratitis patients, immunosuppressed cases and environmental sources as of various geographies of Iran.Results: T4 genotype was the predominant strain in Iran, and the rare genotypes belonged to T2, T3, T5(Acanthamoeba lenticulata), T6, T9, T11, T13 and T15(Acanthamoeba jacobsi).A total of 47 unique haplotypes of T4 were identified. A parsimonious network of the sequence haplotypes demonstrated star-like feature containing haplogroups IR6(34.1%) and IR7(31.2%) as the most common haplotypes. In accordance with the analysis of molecular variance, the high value of haplotype diversity(0.612–0.848) of Acanthamoeba T4 represented genetic variability within populations. Neutrality indices of the 18 S ribosomal RNA demonstrated negative values in all populations which represented a considerable divergence from neutrality. The majority of genetic diversity belonged to the infected contact lens and dust samples in immunodeficiency and ophthalmology wards, which indicated potential routes for exposure to a pathogenic Acanthamoeba sp. in at-risk individuals. A pairwise fixation index(FST) was from low to high values(0.024 33–0.418 92). The statistically FST points out that T4 is genetically differentiated between north-west, north-south and centralsouth metapopulations, but not differentiated between west-central, west-south, centralsouth, and north-central isolates.Conclusions: An occurrence of IR6 and IR7 displays that possibly a gene flow of Acanthamoeba T4 occurred after the founder effect or bottleneck experience through ecological changes or host mobility. This is the first systematic review and meta-analysis providing new approaches into gene migration and transmission patterns of Acanthamoeba sp, and targeting at the high-risk individuals/sources among the various regions of Iran.展开更多
According to investigation on two species of melitaeine butterflies in Yanjiaping Village, Chicheng County, Hebei Province, China, between 1998—2002, to-gether with the use of 1︰10000 contour map of the local area, ...According to investigation on two species of melitaeine butterflies in Yanjiaping Village, Chicheng County, Hebei Province, China, between 1998—2002, to-gether with the use of 1︰10000 contour map of the local area, some conclusions are shown by the SPSS and GIS analysis of data obained from GPS: (1) The two species of melitaeine butterflies have different metapopulation struc-tures. M. phoebe is a source-sink metapopulation, while E. aurinia is a classical metapopulation, supporting the analytic result from our former genetic research. (2) The two species of melitaeine butterflies exhibit different trends of popula-tion dynamics. M. phoebe source-sink metapopulation is very unsteady, and is always small, thus has a tendency to go ex-tinct gradually. But E. aurinia classical metapopulation is stable, and has maintained a larger population size. There-fore, it stands a better chance of long-term survival. (3) The two species of melitaeine butterflies are significantly related in both patch occupancy and local population size. (4) The effect of isolation is significant on the metapopulations of these two species of melitaeine butterflies, consistent with the classical theories, whereas the effect of patch area is not sig-nificant on the metapopulations of these two species of meli-taeine butterflies, which is inconsistent with the classical theories. Therefore, other factors, such as habitat quality, should be considered for their influences on metapopula-tions.展开更多
This article discusses the influence of phenology-related intraseasonal asynchrony on metapopulation dynamics and stability. As the part played by intraseasonal asynchrony is as yet unclear and poorly described, great...This article discusses the influence of phenology-related intraseasonal asynchrony on metapopulation dynamics and stability. As the part played by intraseasonal asynchrony is as yet unclear and poorly described, greater account of it should be taken in both metapopulation research and conservation practice. The subpopulations of the Parnassius mnemosyne metapopulation studied here are strongly isolated because of the phenological shift between them, despite the relatively small physical distances between them. This isolation is the result of a significant temporal shift in the species' flight periods in the main metapopulation centers: in som e seasons its flight times in the different subpopulations did not overlap at all. The predicted results of such strong intraseasonal asynchrony are not altogether clear. On the one hand, they reduce the vulnerability of the entire metapopulation to the effects of short-term random disasters. On the other, the ever-greater isolation of subpopulations may cause the metapopulation to becom e a nonequilibrium one, which will have a serious impact on its long-term survival.展开更多
India has been the latest global epicenter for COVID-19,a novel coronavirus disease that emerged in China in late 2019.We present a base mathematical model for the transmission dynamics of COVID-19 in India and its ne...India has been the latest global epicenter for COVID-19,a novel coronavirus disease that emerged in China in late 2019.We present a base mathematical model for the transmission dynamics of COVID-19 in India and its neighbor,Pakistan.The base model was rigorously analyzed and parameterized using cumulative COVID-19 mortality data from each of the two countries.The model was used to assess the population-level impact of the control and mitigation strategies implemented in the two countries(notably non-pharmaceutical interventions).Numerical simulations of the basic model indicate that,based on the current baseline levels of the control and mitigation strategies implemented,the pandemic trajectory in India is on a downward trend.This downward trend will be reversed,and India will be recording mild outbreaks,if the control and mitigation strategies are relaxed from their current levels.By early September 2021,our simulations suggest that India could record up to 460,000 cumulative deaths under baseline levels of the implemented control strategies,while Pakistan(where the pandemic is comparatively milder)could see over 24,000 cumulative deaths at current mitigation levels.The basic model was extended to assess the impact of back-and-forth mobility between the two countries.Simulations of the resulting metapopulation model show that the burden of the COVID-19 pandemic in Pakistan increases with increasing values of the average time residents of India spend in Pakistan,with daily mortality in Pakistan peaking in mid-August to mid-September of 2021.Under the respective baseline control scenarios,our simulations show that the backand-forth mobility between India and Pakistan could delay the time-to-elimination of the COVID-19 pandemic in India and Pakistan to November 2022 and July 2022,respectively.展开更多
The spread of methicillin-resistant strains of Staphylococcus aureus(MRSA)in health-care settings has become increasingly difficult to control and has since been able to spread in the general community.The prevalence ...The spread of methicillin-resistant strains of Staphylococcus aureus(MRSA)in health-care settings has become increasingly difficult to control and has since been able to spread in the general community.The prevalence of MRSA within the general public has caused outbreaks in groups of people in close quarters such as military barracks,gyms,daycare centres and correctional facilities.Correctional facilities are of particular importance for spreading MRSA,as inmates are often in close proximity and have limited access to hygienic products and clean clothing.Although these conditions are ideal for spreading MRSA,a recent study has suggested that recurrent epidemics are caused by the influx of colonized or infected individuals into the correctional facility.In this paper,we further investigate the effects of community dynamics on the spread of MRSA within the correctional facility and determine whether recidivism has a significant effect on disease dynamics.Using a simplified hotspot model ignoring disease dynamics within the correctional facility,as well as two metapopulation models,we demonstrate that outbreaks in correctional facilities can be driven by community dynamics even when spread between inmates is restricted.We also show that disease dynamics within the correctional facility and their effect on the outlying community may be ignored due to the smaller size of the incarcerated population.This will allow construction of simpler models that consider the effects of many MRSA hotspots interacting with the general community.It is suspected that the cumulative effects of hotspots for MRSA would have a stronger feedback effect in other community settings.展开更多
Background:Philopatry rate is one of the main factors shaping population dynamics in colonial seabirds.Low rates of philopatry are linked to populations with high dispersal,while high rates are linked to populations w...Background:Philopatry rate is one of the main factors shaping population dynamics in colonial seabirds.Low rates of philopatry are linked to populations with high dispersal,while high rates are linked to populations with a very high spatial structure pattern(i.e.,metapopulations).The Cantabrian Yellow-legged Gull(Larus michahellis)population is considered to be resident,with relatively low dispersal rates.Precise estimations of its philopatry rates are however still lacking.Here,we aimed to estimate philopatry rates in the main Yellow-legged Gull colonies of the province of Gipuzkoa,in the southeastern part of the Bay of Biscay.Methods:We analysed 734 resightings,during the breeding season at the colonies of Getaria,Santa Clara and Ulia,relative to a total of 3245 individuals ringed at birth in these same colonies during a period of 13 years.These data were analysed using Multi-State Recapture models in MARK.Results:After controlling survival and resighting probability,the average dispersal rate among colonies was 4%(±SD=2%)when individuals are immature,decreasing to 1±1%)for adult breeding gulls(i.e.,philopatry rate was 99%).Annual survival rates were assessed to be 0.27±0.02 for birds in their first year of life and 0.87±0.01 for older individuals.The probability of observing immature birds in the colonies was 0.08±0.01,as compared to 0.21±0.02 in adult birds.Conclusions:We obtained evidence of extremely high local philopatry rates,clearly within the upper limit found in gulls.A high philopatry favour a speciation in these species who are vulnerable to obtain the main food source(land-fills and fishing discard)which are transforming under new ecological process.展开更多
The construction of nature reserves plays an essential role in protecting natural resources and the ecological environment,especially the conservation of rare and endangered species,which also has a vital function in ...The construction of nature reserves plays an essential role in protecting natural resources and the ecological environment,especially the conservation of rare and endangered species,which also has a vital function in maintaining the ecological security of the national territory.China has built up a comprehensive network of nature reserves after waves of development,but there are still many problems with the management of nature reserves,such as the definition of boundaries,zoning theory,zoning methods,and legal protection.The definition of boundaries is a tool for effective management of nature reserves,but achieving scientific and effective boundary definition is a difficult problem for the construction and management of reserves.It is also a problem that must be solved to achieve sustainable development.This paper compared three fundamental theories of the conservation of species in nature reserves,namely island biogeography,metapopulation,and landscape ecology,from connotations,applications and advantages,and disadvantages,and discussed the progress of theoretical research to provide valuable references for the definition and planning of effective boundaries of nature reserves.展开更多
The regime of disturbance with natural or anthropogenic origin can lead to the destabilization or even to a mass mortality of benthic communities. Due to the heterogeneity of the disturbance there is a formation of pa...The regime of disturbance with natural or anthropogenic origin can lead to the destabilization or even to a mass mortality of benthic communities. Due to the heterogeneity of the disturbance there is a formation of patches in different stages of ecological succession. The aim of this study is to follow and describe the resilience in artificial disturbed sediment in a polluted bay in Rio de Janeiro. The sediment was collected, sterilized and placed inside corers (10 cmdiameter ×15 cmheight) in the same place where it was collected. We allocated the samples in two structures, the difference between them was that one was placed closed to the bottom and the other was placed50 cmheight. We found 2352 organisms distributed in 14 taxons. The class Polychaeta and the order Amphipoda showed the highest density in all the survey and treatments. We identified the factors influencing the scenarium: different mechanisms of dispersal, the position of the structures and life history of each group. Disturbance can be the main cause of the patch’s diversity found in estuaries and coastal areas. Because of this, monitoring of selected areas becomes an important tool to understand the regime of disturbance as a key factor structuring benthic communities in soft sediment, also suggesting a metapopulation dynamics.展开更多
Dispersal is a central aspect of the ecology, evolution, and conservation of species. Predicting how species will respond to changing environmental conditions requires understanding factors that produce variation in d...Dispersal is a central aspect of the ecology, evolution, and conservation of species. Predicting how species will respond to changing environmental conditions requires understanding factors that produce variation in dispersal. We explore one source of variation, differences between sexes within a spatial population network. Here, we compare the dispersal patterns of male and female Parnassius smintheus among 18 subpopulations over 8 years using the Virtual Migration Model. Estimated dispersal parameters differed between males and females, particularly with respect to movement through meadow and forest matrix habitat. The estimated dispersal distances of males through forest were much less than for females. Observations of female movement showed that, unlike males, females do not avoid forest nor does forest exert an edge effect. We explored whether further forest encroachment in this system would have different effects for males and females by fitting mean parameter estimates to the landscape configuration seen in 1993 and 2012. Despite differences in their dispersal due presumably to both habitat and physiological differences, males and females are predicted to respond in similar ways to reduced meadow area and increased forest isolation.展开更多
In the study area (Yanjiaping Village, Hebei Province, China), grazing extensity varies at different loca-tions, small and discontinuous croplands are imbedded in some arid grassland, which are habitats for the melita...In the study area (Yanjiaping Village, Hebei Province, China), grazing extensity varies at different loca-tions, small and discontinuous croplands are imbedded in some arid grassland, which are habitats for the melitaeine butterflies, Euphydryas aurinia and Melitaea phoebe. These two species of butterflies coexist in this area, in which grazing and cultivation are the main disturbances. Grazing and cultivation have a reciprocal effect on E. aurinia, rather than M. phoebe. We observed that E. aurinia preferred to occupy patches with moderate grazing and imbedded with small and discontinuous croplands, where E. aurinia also has high population density. The percentage of E. aurinia larval groups in the ribbings was significantly higher than that of M. phoebe, whereas larvae of both species tended to increase in recent years. Our data also showed that the population density and the patch occupancy rate of both E. aurinia and M. phoebe were the highest under moderate grazing. It indicates that cultivation of small and dis-continuous croplands within the patch has a significant effect on the population density of both spe-cies of melitaeine butterflies. Thus, to artificially create or maintain semi-natural habitats, comple-mented by moderate grazing, might be an ecological strategy to conserve melitaeine butterflies effec-tively. Considering the distinct impacts of cultivation and grazing on the population distribution and dynamics of the two different species, human disturbance in the mountainous area might be strategi-cally involved in proposing conservation plans for the target species in the future.展开更多
A growing number of studies have looked at how climate change alters the effects of habitat fragmentation and degradation on both single and multiple species;some raise concern that biodiversity loss and its effects w...A growing number of studies have looked at how climate change alters the effects of habitat fragmentation and degradation on both single and multiple species;some raise concern that biodiversity loss and its effects will be exacerbated.The published literature on spatial dynamics(such as dispersal and metapopulation dynamics),habitat fragmentation and climate change requires synthesis and a conceptual framework to simplify thinking.We propose a framework that integrates how climate change affects spatial population dynamics and the effects of habitat fragmentation in terms of:(i)habitat quality,quantity and distribution;(ii)habitat connectivity;and(iii)the dynamics of habitat itself.We use the framework to categorize existing autecological studies and investigate how each is affected by anthropogenic climate change.It is clear that a changing climate produces changes in the geographic distribution of climatic conditions,and the amount and quality of habitat.The most thorough published studies show how such changes impact metapopulation persistence,source-sink dynamics,changes in species’geographic range and community composition.Climate-related changes in movement behavior and quantity,quality and distribution of habitat have also produced empirical changes in habitat connectivity for some species.An underexplored area is how habitat dynamics that are driven by climatic processes will affect species that live in dynamic habitats.We end our discussion by suggesting ways to improve current attempts to integrate climate change,spatial population dynamics and habitat fragmentation effects,and suggest distinct areas of study that might provide opportunities for more fully integrative work.展开更多
N_(a)tural populations often persist at the landscape scale as metapopulations,with breeding units(subpopulations)experiencing temporal extinction and recolonization events.Important parameters to forecast population ...N_(a)tural populations often persist at the landscape scale as metapopulations,with breeding units(subpopulations)experiencing temporal extinction and recolonization events.Important parameters to forecast population viability in these systems include the ratio of the effective number of breeders(N_(b))to the total number of adults(N_(a))and migration rates among subpopulations.Here,we present the results of a 10-year integrative monitoring program of a metapopulation of the Iberian green frog(Pelophylax perezi)in central Spain.We characterized population dynamics at two main breeding ponds(Gravera and Laguna)using capture-mark-recapture data to estimate N_(a)in each breeding season,and multilocus genotypes to estimate the effective population size(Ne),N_(b),individual breeding success,and migration rates.Both ponds experienced population decline after a dry season,with Gravera subsequently recovering and Laguna suffering a bottleneck associated with genetic impoverishment.In this subpopulation,average allelic richness and private alleles decreased from 2010(10.87 and 1.67,respectively)to 2018(8.0 and 0.20).The N_(b)/N_(a)ratio in Laguna in 2018 was twice as high(0.95)than in Gravera(0.41)or in pre-bottleneck Laguna(0.50),suggesting plasticity or genetic compensation through increased individual breeding success.Migration rates were asymmetric between ponds,with a stronger contribution from Gravera to Laguna(29.9%vs.16.2%in the opposite direction)that may result in a rescue effect.This study emphasizes the importance of integrative demographic approaches for the monitoring of natural populations based on a better understanding of their spatio-temporal dynamics,which provides valuable information for conservation actions.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11072107,91016022,and 11232007)the Research Fund of State Key Laboratory of Mechanics and Control of Mechanical Structures of Nanjing University of Aeronautics and astronautics,China(Grant No.0113G01)+1 种基金the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province,China(Grant No.13KJB110006)the Project Fund of Jiangsu University of Science and Technology,China(Grant No.633051203)
文摘We investigate the stochastic resonance (SR) phenomenon induced by the periodic signal in a metapopulation system with colored noises. The analytical expression of signal-to-noise is derived in the adiabatic limit. By numerical calculation, the effects of the addictive noise intensity, the multiplicative noise intensity and two noise self-correlation times on SNR are respectively discussed. It shows that: (i) in the case that the addictive noise intensity M takes a small value, a SR phenomenon for the curve of SNR appears; however, when M takes a large value, SNR turns into a monotonic function on the multiplicative noise intensity Q. (ii) The resonance peaks in the plots of the multiplicative noise intensity Q versus its self-correlation time Vl and the addictive noise intensity M versus its self-correlation time ~2 translate in parallel. Mean- while, a parallel translation also appears in the plots of vl versus Q and v2 versus M. (iii) The interactive effects between self-correlation times Vl and v2 are opposite.
文摘Hydrobiidae is one of the most diverse taxa among limnic and estuarine mollusks. Patterns of spatial and seasonal distribution of Heleobia australis were studied in ten stations over two years, in the urban eutrophic bay of Guanabara, Rio de Janeiro, Brazil. Spatial dispersal strategies in adults of this species, analyzed in the laboratory, revealed three patterns: 1) mobility on soft sediments;2) mobility on hard substrata;and 3) the ability to lift from the bottom to the surface, to again sink down. This facilitate species movement from one location to another by surface currents or attached to floating debris. Thus, individuals are able to escape from an impacted area and further re-colonize other patches after recovering from local impacts. The hypothesis of metapopulation dynamics (source– sink) was analyzed. Two stations with high and constant numbers of individuals were grouped and tested as possible ‘sources’. The number of specimens in the remaining stations was highly variable, even with the complete disappearance and posterior highly dense re-occurrence of the mollusk, whereby these were tested as possible ‘sinks’. Results derived from nested ANOVA supported the hypothesis of metapopulation dynamics in the case of H. australis adults, ex-pressed through opportunistic-species domi- nation of a highly impacted estuarine system, such as Guanabara Bay.
基金financially supported by Immunology Research Center,Tabriz University of Medical Sciences,Tabriz,Iran
文摘Objective: To verify phylogeography and genetic structure of Acanthamoeba populations among the Iranian clinical isolates and natural/artificial environments distributed in various regions of the country.Methods: We searched electronic databases including Medline, Pub Med, Science Direct, Scopus and Google Scholar from 2005 to 2016. To explore the genetic variability of Acanthamoeba sp, 205 sequences were retrieved from keratitis patients, immunosuppressed cases and environmental sources as of various geographies of Iran.Results: T4 genotype was the predominant strain in Iran, and the rare genotypes belonged to T2, T3, T5(Acanthamoeba lenticulata), T6, T9, T11, T13 and T15(Acanthamoeba jacobsi).A total of 47 unique haplotypes of T4 were identified. A parsimonious network of the sequence haplotypes demonstrated star-like feature containing haplogroups IR6(34.1%) and IR7(31.2%) as the most common haplotypes. In accordance with the analysis of molecular variance, the high value of haplotype diversity(0.612–0.848) of Acanthamoeba T4 represented genetic variability within populations. Neutrality indices of the 18 S ribosomal RNA demonstrated negative values in all populations which represented a considerable divergence from neutrality. The majority of genetic diversity belonged to the infected contact lens and dust samples in immunodeficiency and ophthalmology wards, which indicated potential routes for exposure to a pathogenic Acanthamoeba sp. in at-risk individuals. A pairwise fixation index(FST) was from low to high values(0.024 33–0.418 92). The statistically FST points out that T4 is genetically differentiated between north-west, north-south and centralsouth metapopulations, but not differentiated between west-central, west-south, centralsouth, and north-central isolates.Conclusions: An occurrence of IR6 and IR7 displays that possibly a gene flow of Acanthamoeba T4 occurred after the founder effect or bottleneck experience through ecological changes or host mobility. This is the first systematic review and meta-analysis providing new approaches into gene migration and transmission patterns of Acanthamoeba sp, and targeting at the high-risk individuals/sources among the various regions of Iran.
文摘According to investigation on two species of melitaeine butterflies in Yanjiaping Village, Chicheng County, Hebei Province, China, between 1998—2002, to-gether with the use of 1︰10000 contour map of the local area, some conclusions are shown by the SPSS and GIS analysis of data obained from GPS: (1) The two species of melitaeine butterflies have different metapopulation struc-tures. M. phoebe is a source-sink metapopulation, while E. aurinia is a classical metapopulation, supporting the analytic result from our former genetic research. (2) The two species of melitaeine butterflies exhibit different trends of popula-tion dynamics. M. phoebe source-sink metapopulation is very unsteady, and is always small, thus has a tendency to go ex-tinct gradually. But E. aurinia classical metapopulation is stable, and has maintained a larger population size. There-fore, it stands a better chance of long-term survival. (3) The two species of melitaeine butterflies are significantly related in both patch occupancy and local population size. (4) The effect of isolation is significant on the metapopulations of these two species of melitaeine butterflies, consistent with the classical theories, whereas the effect of patch area is not sig-nificant on the metapopulations of these two species of meli-taeine butterflies, which is inconsistent with the classical theories. Therefore, other factors, such as habitat quality, should be considered for their influences on metapopula-tions.
文摘This article discusses the influence of phenology-related intraseasonal asynchrony on metapopulation dynamics and stability. As the part played by intraseasonal asynchrony is as yet unclear and poorly described, greater account of it should be taken in both metapopulation research and conservation practice. The subpopulations of the Parnassius mnemosyne metapopulation studied here are strongly isolated because of the phenological shift between them, despite the relatively small physical distances between them. This isolation is the result of a significant temporal shift in the species' flight periods in the main metapopulation centers: in som e seasons its flight times in the different subpopulations did not overlap at all. The predicted results of such strong intraseasonal asynchrony are not altogether clear. On the one hand, they reduce the vulnerability of the entire metapopulation to the effects of short-term random disasters. On the other, the ever-greater isolation of subpopulations may cause the metapopulation to becom e a nonequilibrium one, which will have a serious impact on its long-term survival.
基金One of the authors(ABG)acknowledge the support,in part,of the Simons Foundation(Award#585022)the National Science Foundation(Grant Number:DMS-2052363)Another author(SS)acknowledges the support of the Fulbright Scholarship.
文摘India has been the latest global epicenter for COVID-19,a novel coronavirus disease that emerged in China in late 2019.We present a base mathematical model for the transmission dynamics of COVID-19 in India and its neighbor,Pakistan.The base model was rigorously analyzed and parameterized using cumulative COVID-19 mortality data from each of the two countries.The model was used to assess the population-level impact of the control and mitigation strategies implemented in the two countries(notably non-pharmaceutical interventions).Numerical simulations of the basic model indicate that,based on the current baseline levels of the control and mitigation strategies implemented,the pandemic trajectory in India is on a downward trend.This downward trend will be reversed,and India will be recording mild outbreaks,if the control and mitigation strategies are relaxed from their current levels.By early September 2021,our simulations suggest that India could record up to 460,000 cumulative deaths under baseline levels of the implemented control strategies,while Pakistan(where the pandemic is comparatively milder)could see over 24,000 cumulative deaths at current mitigation levels.The basic model was extended to assess the impact of back-and-forth mobility between the two countries.Simulations of the resulting metapopulation model show that the burden of the COVID-19 pandemic in Pakistan increases with increasing values of the average time residents of India spend in Pakistan,with daily mortality in Pakistan peaking in mid-August to mid-September of 2021.Under the respective baseline control scenarios,our simulations show that the backand-forth mobility between India and Pakistan could delay the time-to-elimination of the COVID-19 pandemic in India and Pakistan to November 2022 and July 2022,respectively.
文摘The spread of methicillin-resistant strains of Staphylococcus aureus(MRSA)in health-care settings has become increasingly difficult to control and has since been able to spread in the general community.The prevalence of MRSA within the general public has caused outbreaks in groups of people in close quarters such as military barracks,gyms,daycare centres and correctional facilities.Correctional facilities are of particular importance for spreading MRSA,as inmates are often in close proximity and have limited access to hygienic products and clean clothing.Although these conditions are ideal for spreading MRSA,a recent study has suggested that recurrent epidemics are caused by the influx of colonized or infected individuals into the correctional facility.In this paper,we further investigate the effects of community dynamics on the spread of MRSA within the correctional facility and determine whether recidivism has a significant effect on disease dynamics.Using a simplified hotspot model ignoring disease dynamics within the correctional facility,as well as two metapopulation models,we demonstrate that outbreaks in correctional facilities can be driven by community dynamics even when spread between inmates is restricted.We also show that disease dynamics within the correctional facility and their effect on the outlying community may be ignored due to the smaller size of the incarcerated population.This will allow construction of simpler models that consider the effects of many MRSA hotspots interacting with the general community.It is suspected that the cumulative effects of hotspots for MRSA would have a stronger feedback effect in other community settings.
基金This research was partly funded by the Basque Government and the Gipuzkoa Regional Council.SD benefited from a pre-doctoral fellowship from the Basque Government.
文摘Background:Philopatry rate is one of the main factors shaping population dynamics in colonial seabirds.Low rates of philopatry are linked to populations with high dispersal,while high rates are linked to populations with a very high spatial structure pattern(i.e.,metapopulations).The Cantabrian Yellow-legged Gull(Larus michahellis)population is considered to be resident,with relatively low dispersal rates.Precise estimations of its philopatry rates are however still lacking.Here,we aimed to estimate philopatry rates in the main Yellow-legged Gull colonies of the province of Gipuzkoa,in the southeastern part of the Bay of Biscay.Methods:We analysed 734 resightings,during the breeding season at the colonies of Getaria,Santa Clara and Ulia,relative to a total of 3245 individuals ringed at birth in these same colonies during a period of 13 years.These data were analysed using Multi-State Recapture models in MARK.Results:After controlling survival and resighting probability,the average dispersal rate among colonies was 4%(±SD=2%)when individuals are immature,decreasing to 1±1%)for adult breeding gulls(i.e.,philopatry rate was 99%).Annual survival rates were assessed to be 0.27±0.02 for birds in their first year of life and 0.87±0.01 for older individuals.The probability of observing immature birds in the colonies was 0.08±0.01,as compared to 0.21±0.02 in adult birds.Conclusions:We obtained evidence of extremely high local philopatry rates,clearly within the upper limit found in gulls.A high philopatry favour a speciation in these species who are vulnerable to obtain the main food source(land-fills and fishing discard)which are transforming under new ecological process.
基金Supported by the Central Universities Basic Research Operations Project(JS2019HGXJ0027).
文摘The construction of nature reserves plays an essential role in protecting natural resources and the ecological environment,especially the conservation of rare and endangered species,which also has a vital function in maintaining the ecological security of the national territory.China has built up a comprehensive network of nature reserves after waves of development,but there are still many problems with the management of nature reserves,such as the definition of boundaries,zoning theory,zoning methods,and legal protection.The definition of boundaries is a tool for effective management of nature reserves,but achieving scientific and effective boundary definition is a difficult problem for the construction and management of reserves.It is also a problem that must be solved to achieve sustainable development.This paper compared three fundamental theories of the conservation of species in nature reserves,namely island biogeography,metapopulation,and landscape ecology,from connotations,applications and advantages,and disadvantages,and discussed the progress of theoretical research to provide valuable references for the definition and planning of effective boundaries of nature reserves.
文摘The regime of disturbance with natural or anthropogenic origin can lead to the destabilization or even to a mass mortality of benthic communities. Due to the heterogeneity of the disturbance there is a formation of patches in different stages of ecological succession. The aim of this study is to follow and describe the resilience in artificial disturbed sediment in a polluted bay in Rio de Janeiro. The sediment was collected, sterilized and placed inside corers (10 cmdiameter ×15 cmheight) in the same place where it was collected. We allocated the samples in two structures, the difference between them was that one was placed closed to the bottom and the other was placed50 cmheight. We found 2352 organisms distributed in 14 taxons. The class Polychaeta and the order Amphipoda showed the highest density in all the survey and treatments. We identified the factors influencing the scenarium: different mechanisms of dispersal, the position of the structures and life history of each group. Disturbance can be the main cause of the patch’s diversity found in estuaries and coastal areas. Because of this, monitoring of selected areas becomes an important tool to understand the regime of disturbance as a key factor structuring benthic communities in soft sediment, also suggesting a metapopulation dynamics.
文摘Dispersal is a central aspect of the ecology, evolution, and conservation of species. Predicting how species will respond to changing environmental conditions requires understanding factors that produce variation in dispersal. We explore one source of variation, differences between sexes within a spatial population network. Here, we compare the dispersal patterns of male and female Parnassius smintheus among 18 subpopulations over 8 years using the Virtual Migration Model. Estimated dispersal parameters differed between males and females, particularly with respect to movement through meadow and forest matrix habitat. The estimated dispersal distances of males through forest were much less than for females. Observations of female movement showed that, unlike males, females do not avoid forest nor does forest exert an edge effect. We explored whether further forest encroachment in this system would have different effects for males and females by fitting mean parameter estimates to the landscape configuration seen in 1993 and 2012. Despite differences in their dispersal due presumably to both habitat and physiological differences, males and females are predicted to respond in similar ways to reduced meadow area and increased forest isolation.
基金the National Natural Science Foundation of China (Grant Nos. 39893360 and 30270241)the Chinese Ministry of Education (Grant No. 272007)
文摘In the study area (Yanjiaping Village, Hebei Province, China), grazing extensity varies at different loca-tions, small and discontinuous croplands are imbedded in some arid grassland, which are habitats for the melitaeine butterflies, Euphydryas aurinia and Melitaea phoebe. These two species of butterflies coexist in this area, in which grazing and cultivation are the main disturbances. Grazing and cultivation have a reciprocal effect on E. aurinia, rather than M. phoebe. We observed that E. aurinia preferred to occupy patches with moderate grazing and imbedded with small and discontinuous croplands, where E. aurinia also has high population density. The percentage of E. aurinia larval groups in the ribbings was significantly higher than that of M. phoebe, whereas larvae of both species tended to increase in recent years. Our data also showed that the population density and the patch occupancy rate of both E. aurinia and M. phoebe were the highest under moderate grazing. It indicates that cultivation of small and dis-continuous croplands within the patch has a significant effect on the population density of both spe-cies of melitaeine butterflies. Thus, to artificially create or maintain semi-natural habitats, comple-mented by moderate grazing, might be an ecological strategy to conserve melitaeine butterflies effec-tively. Considering the distinct impacts of cultivation and grazing on the population distribution and dynamics of the two different species, human disturbance in the mountainous area might be strategi-cally involved in proposing conservation plans for the target species in the future.
文摘A growing number of studies have looked at how climate change alters the effects of habitat fragmentation and degradation on both single and multiple species;some raise concern that biodiversity loss and its effects will be exacerbated.The published literature on spatial dynamics(such as dispersal and metapopulation dynamics),habitat fragmentation and climate change requires synthesis and a conceptual framework to simplify thinking.We propose a framework that integrates how climate change affects spatial population dynamics and the effects of habitat fragmentation in terms of:(i)habitat quality,quantity and distribution;(ii)habitat connectivity;and(iii)the dynamics of habitat itself.We use the framework to categorize existing autecological studies and investigate how each is affected by anthropogenic climate change.It is clear that a changing climate produces changes in the geographic distribution of climatic conditions,and the amount and quality of habitat.The most thorough published studies show how such changes impact metapopulation persistence,source-sink dynamics,changes in species’geographic range and community composition.Climate-related changes in movement behavior and quantity,quality and distribution of habitat have also produced empirical changes in habitat connectivity for some species.An underexplored area is how habitat dynamics that are driven by climatic processes will affect species that live in dynamic habitats.We end our discussion by suggesting ways to improve current attempts to integrate climate change,spatial population dynamics and habitat fragmentation effects,and suggest distinct areas of study that might provide opportunities for more fully integrative work.
基金the Ethics Committee of Consejo Superior de Investigaciones Científicas,Spain(ref.:710/2018)and Comunidad de Madrid(ref.:PROEX 040/19)which also extended legal permits for tissue collection for scientific purposes(ref.:10/069513.9/18)This study was funded by FEDER/Ministerio de Ciencia,Innovación y Universidades-Agencia Estatal de Investigación,Spain,grant CGL2017-83131-P。
文摘N_(a)tural populations often persist at the landscape scale as metapopulations,with breeding units(subpopulations)experiencing temporal extinction and recolonization events.Important parameters to forecast population viability in these systems include the ratio of the effective number of breeders(N_(b))to the total number of adults(N_(a))and migration rates among subpopulations.Here,we present the results of a 10-year integrative monitoring program of a metapopulation of the Iberian green frog(Pelophylax perezi)in central Spain.We characterized population dynamics at two main breeding ponds(Gravera and Laguna)using capture-mark-recapture data to estimate N_(a)in each breeding season,and multilocus genotypes to estimate the effective population size(Ne),N_(b),individual breeding success,and migration rates.Both ponds experienced population decline after a dry season,with Gravera subsequently recovering and Laguna suffering a bottleneck associated with genetic impoverishment.In this subpopulation,average allelic richness and private alleles decreased from 2010(10.87 and 1.67,respectively)to 2018(8.0 and 0.20).The N_(b)/N_(a)ratio in Laguna in 2018 was twice as high(0.95)than in Gravera(0.41)or in pre-bottleneck Laguna(0.50),suggesting plasticity or genetic compensation through increased individual breeding success.Migration rates were asymmetric between ponds,with a stronger contribution from Gravera to Laguna(29.9%vs.16.2%in the opposite direction)that may result in a rescue effect.This study emphasizes the importance of integrative demographic approaches for the monitoring of natural populations based on a better understanding of their spatio-temporal dynamics,which provides valuable information for conservation actions.