Ctenophore Pleurobrachia globosa(P.globosa)invades even the northernmost Bohai Sea from the south of China.Three years(2019-2021)of surveys were conducted in the Bohai Bay(BoB)of the Bohai Sea to examine its populatio...Ctenophore Pleurobrachia globosa(P.globosa)invades even the northernmost Bohai Sea from the south of China.Three years(2019-2021)of surveys were conducted in the Bohai Bay(BoB)of the Bohai Sea to examine its population dynamics and potential impact on nuclear power plants.Results show that P.globosa mainly occurred from July to October each year,reaching the maximum abundance in August/September and even bloomed in August 2020.Correlations with environmental factors indicate this species has strong tolerance to acidification and hypoxia,and it has potentially indirect feeding relationship with phytoplankton.Seven stages in three groups were illustrated in life history of P.globosa.Two entire generations were detected in August,confirming its 2-week generation time.Spawning time started earlier in the south than in the north of BoB.The spatiotemporal variation and life cycle of P.globosa in BoB are useful for further study on the invasion,bloom,aggregation,and regeneration of P.globosa.展开更多
The parasitic plant dwarf mistletoe(Arceuthobium) is currently one of the most threatening infestations of coniferous forests worldwide,especially in Eurasia and North America,but its population dynamics in relation t...The parasitic plant dwarf mistletoe(Arceuthobium) is currently one of the most threatening infestations of coniferous forests worldwide,especially in Eurasia and North America,but its population dynamics in relation to one of its hosts(spruce) remain unclear.Here,toward understanding the population dynamics,differential equations were used to construct a life history model for the two populations,and two relatively independent subsystems,host and parasite,were generated from their symbiotic relationships.A suspected-infection model was used to couple them.The resulting models were used to analyze structural changes in the forest.When each infected spruce was assumed to support 1000 parasite shoots,the spruce population first increased rapidly,then slows.When 2000 parasite shoots were assumed,the forest declined dramatically,slipping to zero in the 10 th year,and the spruce seedlings were unable to regenerate.Parasite shoot population curves transformed from exponential J-shapes to logistic S-shapes,reaching population limitations as germination rates changed.These results provide important clues to understanding developmental trends of the present parasite population and will assist in reconstructing invasion histories.展开更多
Gypsy moth, Lymantria dispar （L.） is one of the most widespread defoliators of deciduous and larch forests in Kazakhstan. Preferred host plants, flying capacity of females and neonate caterpillars, preferred places ...Gypsy moth, Lymantria dispar （L.） is one of the most widespread defoliators of deciduous and larch forests in Kazakhstan. Preferred host plants, flying capacity of females and neonate caterpillars, preferred places for egg laying, major factors of mortality and other characteristics vary considerably between different populations of the pest. According to several year researches on gypsy moth, in Kazakhstan, the main biological characteristics of this pest in the regions were investigated. Results of research showed that gypsy moth exists in central and northern of theses regions. From biological and geographical aspects, gypsy moth which there is in Kazakhstan is close to the same species from Siberia western regions. The pest lays on the different heights of trees trunk. It was found that the number of eggs in each egg mass and egg masses laid by the pest are different. The lack of egg eaters and the over- reproduction of the pest at the natural conditions have resulted in the development of bacterial and viral diseases in the populations of this pest from the regions of Kazakhstan to Siberia west.展开更多
The aim of this work was to investigate the fungal population dynamics in ready-to-eat bagged samples of rocket （Diplotaxis spp.）, lettuce baby leaf （Lactuca sativa L.） and ＂songino＂ （Valerianella olitoria L.）...The aim of this work was to investigate the fungal population dynamics in ready-to-eat bagged samples of rocket （Diplotaxis spp.）, lettuce baby leaf （Lactuca sativa L.） and ＂songino＂ （Valerianella olitoria L.） during a shelf-life, in order to evaluate the effects of the storage length and season of production on the spoilage processes. The incidence of toxigenic moulds was particularity studied in order to evaluate a potential production of mycotoxins and allergenic conidia. A total of 900 samples collected from 10 Italian trademarks were analyzed at the 2nd, 5th and 8th day after the packaging in the spring and summer. A very high number of fungi was found and a great variability of moulds and yeasts at the 1 st day of sampling was observed. Regarding to season of production, any seasonal effect on the moulds and yeasts has been observed, but the moulds detected belonged to different species in relation to season. Regarding to storage length, the yeasts and moulds did not showed significant variations during a shelf-life. In relation to vegetable species, the lettuce resulted always less contaminated with respect to other salads, and the rocket presented 1-2 Log cfu/g of increasing in the level of moulds. Regarding to fungi species, the yeasts were significantly predominant respect to moulds. Finally, the toxigenic moulds Aspergillusflavus and Penicillium italicum were found in all the types of salad in the summer, and their growth during the storage at low temperature represented a potential hazard for the mycotoxins and allergenic conidia production in these commodities.展开更多
In this paper,we propose genetic programming(GP) using dynamic population variation(DPV) with four innovations for reducing computational efforts.A new stagnation phase definition and characteristic measure are define...In this paper,we propose genetic programming(GP) using dynamic population variation(DPV) with four innovations for reducing computational efforts.A new stagnation phase definition and characteristic measure are defined for our DPV.The exponential pivot function is proposed to our DPV method in conjunction with the new stagnation phase definition.An appropriate population variation formula is suggested to accelerate convergence.The efficacy of these innovations in our DPV is examined using six benchmark problems.Comparison among the difierent characteristic measures has been conducted for regression problems and the new proposed measure outperformed other measures.It is proved that our DPV has the capacity to provide solutions at a lower computational effort compared with previously proposed DPV methods and standard genetic programming in most cases.Meanwhile,our DPV approach introduced in GP could also rapidly find an excellent solution as well as standard GP in system modeling problems.展开更多
Population dynamics of the Balanus improvises （Crustacean： Cirripedia） was studied in three stations Amirabad, Khazarabad in the eastern part and Noor in the central part of the Southern Coasts of the Caspian Sea. ...Population dynamics of the Balanus improvises （Crustacean： Cirripedia） was studied in three stations Amirabad, Khazarabad in the eastern part and Noor in the central part of the Southern Coasts of the Caspian Sea. Sampling procedure was carried out monthly from July 2007 to July 2008. In this study longitudinal diameter aperture （orifice or opercula diameter） of4118 individuals as well as dry weight and ash free dry weight of 141 barnacles were measured. Barnacle population density decreased in all three stations during autumn and winter. Barnacle density in Khazarabad were significantly higher than the other two stations （P 〉 0/05）. In this study, for dry weight and ash free dry weight maximum 247 and 122 mg and minimum 0/5 and 0/25 mg were obtained respectively. Emergence of a young cohort in March 2008, indicates the reproduction season and larval recruitment at this time. Also the frequency of the larval recruitment from April 2004 until mid-summer had increased. Opercula diameter of B. improvisus correlated with dry weight （R2 = 0/87, n = 115） and ash free dry weight （R2= 0/77, n = 115）. In addition, two equations for correlation of opercula diameter with dry weight （W = 0/49 L2/6, Re= 14） and ash free dry weight （W = 0/16 L2/81, Re = 18/8） for this species were calculated.展开更多
The population size class structure, survival curve, height class structure and population distribution patterns of Ilex cornuta in Longgan Lake National Nature Preserve, Hubei Province, were investigated by using the...The population size class structure, survival curve, height class structure and population distribution patterns of Ilex cornuta in Longgan Lake National Nature Preserve, Hubei Province, were investigated by using the adjacent grid method. The result showed that the population age structure of I. cornuta was of middle-aging type, in the vertical space of population individuals, most of them lived in the shrub layer, and a small number of individuals entered the arborous layer. The distribution pattern of I. cornuta was analyzed by variance /mean ratio method, and the results showed that the distribution pattern of the population was the cluster type. This study can provide references for the further protection, research and development and utilization of I. cornuta .展开更多
Whispering gallery mode resonators(WGMRs)are used as excellent optical feedback components of narrow-linewidth fiber lasers,applied from distributed fiber sensing to optical fiber communication.However,WGMRs lead to o...Whispering gallery mode resonators(WGMRs)are used as excellent optical feedback components of narrow-linewidth fiber lasers,applied from distributed fiber sensing to optical fiber communication.However,WGMRs lead to output of a few microwatts and serious multi-modes in lasers.In this Letter,we fabricated the specially designed WGMR with an overcoupling structure,and its quality(Q)factor was over 10^(9).It improved laser output power significantly.Based on that,dynamic population gratings were applied successfully in the laser.Finally,a single-frequency WGMR fiber laser was realized.Its linewidth was less than 1.07 kHz,its output power was over 0.107 mW,and its spectral signal-to-noise ratio(SNR)was nearly 50 dB.Our research offers a new scheme of a single-frequency narrow-linewidth WGMR fiber laser.展开更多
Many studies have revealed that anchovy has exhibited large variability in population size on decadal tim-escales. However, such works concerning anchovy population are mainly based on short historical catch records. ...Many studies have revealed that anchovy has exhibited large variability in population size on decadal tim-escales. However, such works concerning anchovy population are mainly based on short historical catch records. In order to understand the causes of variability in fish stocks （natural and/or anthropogenic） and calibrate the error between catches and standing stocks, it is essential to develop long-term time series of fish stocks from the time when human impacts are minimal or negligible. Well preserved fish scales from sediment record are regarded as useful indicators revealing the history of fish population dynamics over the last centuries. Anchovy scales was first analyzed over the Yellow Sea and East China Sea and the largest abundance was found in the central South Yellow Sea where is regarded as the largest overwintering ground for Japanese anchovy （Engraulis japonicas）. Thus in the central South Yellow Sea, two cores covering the last 150 years were collected for estimating fish scale flux. The scale deposition rate （SDR） records show that the decadal scale SDRs were obviously coherent between cores with independent chronologies. Thecalibration of downcore SDRs to the standing stocks of anchovy further validated that SDR is a reliable proxy to recon-struct the long-term anchovy population dynamic in the central South Yellow Sea where anoxic conditions prevail in the sediment. When assembled with other productivity proxies, it would be expected that SDR could be associated with changes in oceanic productivity and may make a contribution to determine the forcing factors and elucidate the mechanism of the process in future.展开更多
The endangered Chinese crocodile lizard(Shinisaurus crocodilurus)is a habitat specialist living in streams of mountain forests in southern China and northern Vietnam.Conservation efforts are increasing for recovering ...The endangered Chinese crocodile lizard(Shinisaurus crocodilurus)is a habitat specialist living in streams of mountain forests in southern China and northern Vietnam.Conservation efforts are increasing for recovering its wild populations.However,the growth,reproduction,and dispersal ability of crocodile lizards in the wild are largely unknown.We conducted field surveys of the crocodile lizard population in Daguishan National Nature Reserve,one of the largest extant wild populations of crocodile lizards,for three consecutive years in Guangxi,China.We found that crocodile lizards generally reach sexual maturity at the age of 2.5 years in the wild.Unlike most viviparous lizards,which reproduce annually,the crocodile lizard shows a biennial reproductive cycle.The number of observed juveniles and subadults fluctuated between years,whereas that of adults remained relatively stable.Non-adults had longer three-year dispersal distance than adults.Crocodile lizards showed preference for backwater pools in the stream.Competition for better resources may be the main trigger for dispersal.展开更多
Relatively short historical catch records show that anchovy populations have exhibited large variability over multi-decadal timescales.In order to understand the driving factors(anthropogenic and/or natural) of such v...Relatively short historical catch records show that anchovy populations have exhibited large variability over multi-decadal timescales.In order to understand the driving factors(anthropogenic and/or natural) of such variability,it is essential to develop long-term time series of the population prior to the occurrence of notable anthropogenic impact.Well-preserved fish scales in the sediments are regarded as useful indicators reflecting the fluctuations of fish populations over the last centuries.This study aims to validate the anchovy scale deposition rate as a proxy of local anchovy biomass in the Yellow Sea adjoining the western North Pacific.Our reconstructed results indicated that over the last 150 years,the population size of anchovy in the Yellow Sea has exhibited great fluctuations with periodicity of around 50 years,and the pattern of current recovery and collapse is similar to that of historical records.The pattern of large-scale population synchrony with remote ocean basins provides further evidence proving that fish population dynamics are strongly affected by global and basin-scale oceanic/climatic variability.展开更多
To improve forecasting and sustained control level of underground pests, trapping quantity of underground pests （black cutworm,mole cricket and scar-ab） by lamps and their field dynamics in Hangzhou district from 20...To improve forecasting and sustained control level of underground pests, trapping quantity of underground pests （black cutworm,mole cricket and scar-ab） by lamps and their field dynamics in Hangzhou district from 2005 to 2011 were investigated in the paper. The results showed that different pests had obvious differences in population dynamic. The black cutworm （Agrotis ypsilon） had several damage peaks （late May, late June and late July） and the moth amount in early period was relatively high. The mole cricket （ Gryllotalpa africana） had two damage peaks （late May to early July, early September to mid and late October）. The scarab （Anomala corpulenta） had one damage peak （late May to late June）. There were periodic changes in total quantity of underground pests among years, and the peak period appeared in the year of 2005, 2007 to 2009 and 2011, respectively. On this basis, temperature, humidity, rainfall and light were used as forecas- ting factors, using the method of stepwise regression, 19 factors with significant correlation were screened out and prediction models for occurrence quantity and oc- currence period of the three pests were established. By using accuracy degree judge model for verification, the score values of prediction model for occurrence quan-tity and occurrence period of the three underground pests were more than 58 and 70, which indicated that the historical coincident rate and prediction accuracy of estabhshed prediction models were good.展开更多
The high market demand for endeavour shrimp(Metapenaeus ensis de Haan)has caused intensive fishing for this resource and tends to threaten their sustainability.Assessment of fishing dynamic and stock status of fisheri...The high market demand for endeavour shrimp(Metapenaeus ensis de Haan)has caused intensive fishing for this resource and tends to threaten their sustainability.Assessment of fishing dynamic and stock status of fisheries resource is the main point to formulate its proper sustainable management in the future.The purpose of this study was to determine the stock status of endeavour shrimp in the Bombana and its surrounding waters.The study was conducted from April to November 2021 using a survey method to analyze the length at first capture(L_(c)),length at first maturity(L_(m)),growth rate(K),maximum theoretical carapace length(Loo),and mortality rate such as total mortality rate(Z),fishing mortality rate(F)and natural mortality rate(M).The study results revealed that the endeavour shrimp growth pattern in Bombana was negative allometric and that the ratio of males and females was not balanced.The length at first capture(L_(c))was 29.83 mm(carapace length)and the length at first maturity(L_(m))was at a total carapace length of 31.67 mm.The growth rate(K)was 1.0 per year and maximum theoretical length(L_(∞))was 46.2 mm.The estimate total mortality rate(Z)was 2.52 per year,the fishing mortality rate(F)and natural mortality rate(M)were 0.91 per year and 1.61 per year respectively.The exploitation rate(E)was 0.36 per year,therefore the stock status is not categorized overfishing.In order to ensure the sustainability of the endeavour shrimp,then the effort must be increased by about 28%of the current effort.展开更多
Rodent pest population outbreaks occur frequently in grassland ecosystems in northern China.The Mongolian gerbil(Meriones unguiculatus)is a dominant pest rodent which is distributed across the semi-desert grasslands o...Rodent pest population outbreaks occur frequently in grassland ecosystems in northern China.The Mongolian gerbil(Meriones unguiculatus)is a dominant pest rodent which is distributed across the semi-desert grasslands of Inner Mongolia,China.In 2009,we studied the contraceptive effect of levonorgestrel-quinestrol(EP-1),concentration 50 ppm,on a wild Mongolian gerbil population.The one-off contraceptive treatment was compared with a control group using a semi-monthly live trapping method in the Ordos Semi-desert Grassland Region of Inner Mongolia.The results show that juveniles were not recruited in spring in the treatment group.Ratios of juveniles in the control and treatment groups showed significant semi-monthly differences from spring to summer(one-way ANOVA,F_(2,14)=7.53,P<0.05).Between both groups,annual fluctuations of juvenile and total population densities were significantly different respectively(F_(2,14)=4.64,P<0.05;F_(2,18)=7.72,P<0.05).The contraceptive EP-1 delayed the normal reproductive pattern of Mongolian gerbil populations.This suppressed birth rates of gerbil populations,reduced their densities,and changed their age structures.The period of EP-1 baiting should be extended but it could be an ideal method for controlling Mongolian gerbil populations during each breeding season.展开更多
With the expansion of cities and the emergence of various urban problems,urban underground space has been developed as a solution.In China’s urban transition context,there is a need for the development of underground...With the expansion of cities and the emergence of various urban problems,urban underground space has been developed as a solution.In China’s urban transition context,there is a need for the development of underground space in urban built-up areas.In this casestudy of the central city of Nanjing,we used spatial analysis and statistical methods to characterize the underground space use of urban built-up areas from a dynamic spatiotemporal perspective.We first analyzed the relationship between the population distribution and the underground space use of the central city of Nanjing based on a Baidu heat map,which can reflect the real-time population distribution,and then,we explored the spatiotemporal characteristics and spatial structure of the underground space use in urban built-up areas.The analysis results provide a reference for planning to improve and optimize the layout of underground space in the central city of Nanjing and,more generally,for the stock-type planning of underground space in urban built-up areas.展开更多
The silkworm,Bombyx mori,played an important role in the old Silk Road that connected ancient Asia and Europe.However,to date,there have been few studies of the origins and domestication of this species using molecula...The silkworm,Bombyx mori,played an important role in the old Silk Road that connected ancient Asia and Europe.However,to date,there have been few studies of the origins and domestication of this species using molecular methods.In this study,DNA sequences of mitochondrial and nuclear loci were used to infer the phylogeny and evolutionary history of the domesticated silkworm and its relatives.All of the phylogenetic analyses indicated a close relationship between the domesticated silkworm and the Chinese wild silkworm.Domestication was estimated to have occurred about 4100 years ago(ya),and the radiation of the different geographic strains of B.mori about 2000 ya.The Chinese wild silkworm and the Japanese wild silkworm split about 23600 ya.These estimates are in good agreement with the fossil evidence and historical records.In addition,we show that the domesticated silkworm experienced a population expansion around 1000 ya.The divergence times and the population dynamics of silkworms presented in this study will be useful for studies of lepidopteran phylogenetics,in the genetic analysis of domestic animals,and for understanding the spread of human civilizations.展开更多
The rapid uplift of the Qinghai-Tibet Plateau and its aridification has significantly affected the distribution and community structure of the plants in these regions.However,most of the studies have focussed on vascu...The rapid uplift of the Qinghai-Tibet Plateau and its aridification has significantly affected the distribution and community structure of the plants in these regions.However,most of the studies have focussed on vascular plants,and it has been unclear whether bryophytes,which are haploid plants,had similar historical population dynamics to other vascular plants during the dramatic geological and climatic environment changes of the Quaternary.This study used Syntrichia caninervis Mitt as the research object and investigated its genetic variation,differentiation and population dynamic history in China.We genotyped 27 populations throughout the distributional range of S.caninervis using two chloroplast DNA regions and 19 nuclear microsatellite loci and supplemented these data with ecological niche modelling of the potential distribution areas from the last interglacial period.The results showed that genetic data consistently identified three clades:the Qinghai-Tibet Plateau,Pamir Plateau-TienShan and Central Asia.The genetic variation of Syntrichia caninervis mainly occurred within populations and in the populations within a specific region.However,there was a significant gene exchange between the different regions.S.caninervis may have expanded during the glacial period and shrank during the interglacial period.This study provides new evidence for the dynamic population history of drought-tolerant bryophytes in response to severe environmental changes during the Quaternary glacial and interglacial cycles.展开更多
基金Supported by the National Key Research and Development Program of China(No.2018 YFC 1407501)the State Key Laboratory of Estuarine and Coastal Zone Environment for Environmental Protection,Chinese Research Academy of Environmental Sciences(No.HKHA 2022004)。
文摘Ctenophore Pleurobrachia globosa(P.globosa)invades even the northernmost Bohai Sea from the south of China.Three years(2019-2021)of surveys were conducted in the Bohai Bay(BoB)of the Bohai Sea to examine its population dynamics and potential impact on nuclear power plants.Results show that P.globosa mainly occurred from July to October each year,reaching the maximum abundance in August/September and even bloomed in August 2020.Correlations with environmental factors indicate this species has strong tolerance to acidification and hypoxia,and it has potentially indirect feeding relationship with phytoplankton.Seven stages in three groups were illustrated in life history of P.globosa.Two entire generations were detected in August,confirming its 2-week generation time.Spawning time started earlier in the south than in the north of BoB.The spatiotemporal variation and life cycle of P.globosa in BoB are useful for further study on the invasion,bloom,aggregation,and regeneration of P.globosa.
基金supported by the National Key Research and Development Program (2017 YFD0600105)。
文摘The parasitic plant dwarf mistletoe(Arceuthobium) is currently one of the most threatening infestations of coniferous forests worldwide,especially in Eurasia and North America,but its population dynamics in relation to one of its hosts(spruce) remain unclear.Here,toward understanding the population dynamics,differential equations were used to construct a life history model for the two populations,and two relatively independent subsystems,host and parasite,were generated from their symbiotic relationships.A suspected-infection model was used to couple them.The resulting models were used to analyze structural changes in the forest.When each infected spruce was assumed to support 1000 parasite shoots,the spruce population first increased rapidly,then slows.When 2000 parasite shoots were assumed,the forest declined dramatically,slipping to zero in the 10 th year,and the spruce seedlings were unable to regenerate.Parasite shoot population curves transformed from exponential J-shapes to logistic S-shapes,reaching population limitations as germination rates changed.These results provide important clues to understanding developmental trends of the present parasite population and will assist in reconstructing invasion histories.
文摘Gypsy moth, Lymantria dispar （L.） is one of the most widespread defoliators of deciduous and larch forests in Kazakhstan. Preferred host plants, flying capacity of females and neonate caterpillars, preferred places for egg laying, major factors of mortality and other characteristics vary considerably between different populations of the pest. According to several year researches on gypsy moth, in Kazakhstan, the main biological characteristics of this pest in the regions were investigated. Results of research showed that gypsy moth exists in central and northern of theses regions. From biological and geographical aspects, gypsy moth which there is in Kazakhstan is close to the same species from Siberia western regions. The pest lays on the different heights of trees trunk. It was found that the number of eggs in each egg mass and egg masses laid by the pest are different. The lack of egg eaters and the over- reproduction of the pest at the natural conditions have resulted in the development of bacterial and viral diseases in the populations of this pest from the regions of Kazakhstan to Siberia west.
文摘The aim of this work was to investigate the fungal population dynamics in ready-to-eat bagged samples of rocket （Diplotaxis spp.）, lettuce baby leaf （Lactuca sativa L.） and ＂songino＂ （Valerianella olitoria L.） during a shelf-life, in order to evaluate the effects of the storage length and season of production on the spoilage processes. The incidence of toxigenic moulds was particularity studied in order to evaluate a potential production of mycotoxins and allergenic conidia. A total of 900 samples collected from 10 Italian trademarks were analyzed at the 2nd, 5th and 8th day after the packaging in the spring and summer. A very high number of fungi was found and a great variability of moulds and yeasts at the 1 st day of sampling was observed. Regarding to season of production, any seasonal effect on the moulds and yeasts has been observed, but the moulds detected belonged to different species in relation to season. Regarding to storage length, the yeasts and moulds did not showed significant variations during a shelf-life. In relation to vegetable species, the lettuce resulted always less contaminated with respect to other salads, and the rocket presented 1-2 Log cfu/g of increasing in the level of moulds. Regarding to fungi species, the yeasts were significantly predominant respect to moulds. Finally, the toxigenic moulds Aspergillusflavus and Penicillium italicum were found in all the types of salad in the summer, and their growth during the storage at low temperature represented a potential hazard for the mycotoxins and allergenic conidia production in these commodities.
基金Ministry of Major Science & Technology of Shanghai(No.10DZ1200204)
文摘In this paper,we propose genetic programming(GP) using dynamic population variation(DPV) with four innovations for reducing computational efforts.A new stagnation phase definition and characteristic measure are defined for our DPV.The exponential pivot function is proposed to our DPV method in conjunction with the new stagnation phase definition.An appropriate population variation formula is suggested to accelerate convergence.The efficacy of these innovations in our DPV is examined using six benchmark problems.Comparison among the difierent characteristic measures has been conducted for regression problems and the new proposed measure outperformed other measures.It is proved that our DPV has the capacity to provide solutions at a lower computational effort compared with previously proposed DPV methods and standard genetic programming in most cases.Meanwhile,our DPV approach introduced in GP could also rapidly find an excellent solution as well as standard GP in system modeling problems.
文摘Population dynamics of the Balanus improvises （Crustacean： Cirripedia） was studied in three stations Amirabad, Khazarabad in the eastern part and Noor in the central part of the Southern Coasts of the Caspian Sea. Sampling procedure was carried out monthly from July 2007 to July 2008. In this study longitudinal diameter aperture （orifice or opercula diameter） of4118 individuals as well as dry weight and ash free dry weight of 141 barnacles were measured. Barnacle population density decreased in all three stations during autumn and winter. Barnacle density in Khazarabad were significantly higher than the other two stations （P 〉 0/05）. In this study, for dry weight and ash free dry weight maximum 247 and 122 mg and minimum 0/5 and 0/25 mg were obtained respectively. Emergence of a young cohort in March 2008, indicates the reproduction season and larval recruitment at this time. Also the frequency of the larval recruitment from April 2004 until mid-summer had increased. Opercula diameter of B. improvisus correlated with dry weight （R2 = 0/87, n = 115） and ash free dry weight （R2= 0/77, n = 115）. In addition, two equations for correlation of opercula diameter with dry weight （W = 0/49 L2/6, Re= 14） and ash free dry weight （W = 0/16 L2/81, Re = 18/8） for this species were calculated.
基金Supported by the Team Project of Hubei Collaborative Innovation Center for the Characteristic Resources Exploitation of Dabie Mountains(2015TD06)
文摘The population size class structure, survival curve, height class structure and population distribution patterns of Ilex cornuta in Longgan Lake National Nature Preserve, Hubei Province, were investigated by using the adjacent grid method. The result showed that the population age structure of I. cornuta was of middle-aging type, in the vertical space of population individuals, most of them lived in the shrub layer, and a small number of individuals entered the arborous layer. The distribution pattern of I. cornuta was analyzed by variance /mean ratio method, and the results showed that the distribution pattern of the population was the cluster type. This study can provide references for the further protection, research and development and utilization of I. cornuta .
基金supported by the National Natural Science Foundation of China(Nos.52075131 and 62305006)the Jiangsu Natural Science Foundation(Basic Research Program of Jiangsu Province)(No.BK20230286)。
文摘Whispering gallery mode resonators(WGMRs)are used as excellent optical feedback components of narrow-linewidth fiber lasers,applied from distributed fiber sensing to optical fiber communication.However,WGMRs lead to output of a few microwatts and serious multi-modes in lasers.In this Letter,we fabricated the specially designed WGMR with an overcoupling structure,and its quality(Q)factor was over 10^(9).It improved laser output power significantly.Based on that,dynamic population gratings were applied successfully in the laser.Finally,a single-frequency WGMR fiber laser was realized.Its linewidth was less than 1.07 kHz,its output power was over 0.107 mW,and its spectral signal-to-noise ratio(SNR)was nearly 50 dB.Our research offers a new scheme of a single-frequency narrow-linewidth WGMR fiber laser.
基金The National Basic Research Program of China under contract Nos 2010CB428902 and 2006CB400007the National Natural Science Foundation of China under contract No.40876088
文摘Many studies have revealed that anchovy has exhibited large variability in population size on decadal tim-escales. However, such works concerning anchovy population are mainly based on short historical catch records. In order to understand the causes of variability in fish stocks （natural and/or anthropogenic） and calibrate the error between catches and standing stocks, it is essential to develop long-term time series of fish stocks from the time when human impacts are minimal or negligible. Well preserved fish scales from sediment record are regarded as useful indicators revealing the history of fish population dynamics over the last centuries. Anchovy scales was first analyzed over the Yellow Sea and East China Sea and the largest abundance was found in the central South Yellow Sea where is regarded as the largest overwintering ground for Japanese anchovy （Engraulis japonicas）. Thus in the central South Yellow Sea, two cores covering the last 150 years were collected for estimating fish scale flux. The scale deposition rate （SDR） records show that the decadal scale SDRs were obviously coherent between cores with independent chronologies. Thecalibration of downcore SDRs to the standing stocks of anchovy further validated that SDR is a reliable proxy to recon-struct the long-term anchovy population dynamic in the central South Yellow Sea where anoxic conditions prevail in the sediment. When assembled with other productivity proxies, it would be expected that SDR could be associated with changes in oceanic productivity and may make a contribution to determine the forcing factors and elucidate the mechanism of the process in future.
基金supported by National Natural Science Foundation of China(31901223 and 32170528)National Key Wildlife Protection Project of Central Finance of China(450000215020340001327)。
文摘The endangered Chinese crocodile lizard(Shinisaurus crocodilurus)is a habitat specialist living in streams of mountain forests in southern China and northern Vietnam.Conservation efforts are increasing for recovering its wild populations.However,the growth,reproduction,and dispersal ability of crocodile lizards in the wild are largely unknown.We conducted field surveys of the crocodile lizard population in Daguishan National Nature Reserve,one of the largest extant wild populations of crocodile lizards,for three consecutive years in Guangxi,China.We found that crocodile lizards generally reach sexual maturity at the age of 2.5 years in the wild.Unlike most viviparous lizards,which reproduce annually,the crocodile lizard shows a biennial reproductive cycle.The number of observed juveniles and subadults fluctuated between years,whereas that of adults remained relatively stable.Non-adults had longer three-year dispersal distance than adults.Crocodile lizards showed preference for backwater pools in the stream.Competition for better resources may be the main trigger for dispersal.
基金supported by the National Basic Research Program (973 Program 2010CB428902)the National Natural Science Foundation of China (40876088)
文摘Relatively short historical catch records show that anchovy populations have exhibited large variability over multi-decadal timescales.In order to understand the driving factors(anthropogenic and/or natural) of such variability,it is essential to develop long-term time series of the population prior to the occurrence of notable anthropogenic impact.Well-preserved fish scales in the sediments are regarded as useful indicators reflecting the fluctuations of fish populations over the last centuries.This study aims to validate the anchovy scale deposition rate as a proxy of local anchovy biomass in the Yellow Sea adjoining the western North Pacific.Our reconstructed results indicated that over the last 150 years,the population size of anchovy in the Yellow Sea has exhibited great fluctuations with periodicity of around 50 years,and the pattern of current recovery and collapse is similar to that of historical records.The pattern of large-scale population synchrony with remote ocean basins provides further evidence proving that fish population dynamics are strongly affected by global and basin-scale oceanic/climatic variability.
基金Supported by Science and Technology Project of Hangzhou City (20110232B17)
文摘To improve forecasting and sustained control level of underground pests, trapping quantity of underground pests （black cutworm,mole cricket and scar-ab） by lamps and their field dynamics in Hangzhou district from 2005 to 2011 were investigated in the paper. The results showed that different pests had obvious differences in population dynamic. The black cutworm （Agrotis ypsilon） had several damage peaks （late May, late June and late July） and the moth amount in early period was relatively high. The mole cricket （ Gryllotalpa africana） had two damage peaks （late May to early July, early September to mid and late October）. The scarab （Anomala corpulenta） had one damage peak （late May to late June）. There were periodic changes in total quantity of underground pests among years, and the peak period appeared in the year of 2005, 2007 to 2009 and 2011, respectively. On this basis, temperature, humidity, rainfall and light were used as forecas- ting factors, using the method of stepwise regression, 19 factors with significant correlation were screened out and prediction models for occurrence quantity and oc- currence period of the three pests were established. By using accuracy degree judge model for verification, the score values of prediction model for occurrence quan-tity and occurrence period of the three underground pests were more than 58 and 70, which indicated that the historical coincident rate and prediction accuracy of estabhshed prediction models were good.
文摘The high market demand for endeavour shrimp(Metapenaeus ensis de Haan)has caused intensive fishing for this resource and tends to threaten their sustainability.Assessment of fishing dynamic and stock status of fisheries resource is the main point to formulate its proper sustainable management in the future.The purpose of this study was to determine the stock status of endeavour shrimp in the Bombana and its surrounding waters.The study was conducted from April to November 2021 using a survey method to analyze the length at first capture(L_(c)),length at first maturity(L_(m)),growth rate(K),maximum theoretical carapace length(Loo),and mortality rate such as total mortality rate(Z),fishing mortality rate(F)and natural mortality rate(M).The study results revealed that the endeavour shrimp growth pattern in Bombana was negative allometric and that the ratio of males and females was not balanced.The length at first capture(L_(c))was 29.83 mm(carapace length)and the length at first maturity(L_(m))was at a total carapace length of 31.67 mm.The growth rate(K)was 1.0 per year and maximum theoretical length(L_(∞))was 46.2 mm.The estimate total mortality rate(Z)was 2.52 per year,the fishing mortality rate(F)and natural mortality rate(M)were 0.91 per year and 1.61 per year respectively.The exploitation rate(E)was 0.36 per year,therefore the stock status is not categorized overfishing.In order to ensure the sustainability of the endeavour shrimp,then the effort must be increased by about 28%of the current effort.
基金supported by National Key Basic Research and Development Program of China(No.2007CB109105).
文摘Rodent pest population outbreaks occur frequently in grassland ecosystems in northern China.The Mongolian gerbil(Meriones unguiculatus)is a dominant pest rodent which is distributed across the semi-desert grasslands of Inner Mongolia,China.In 2009,we studied the contraceptive effect of levonorgestrel-quinestrol(EP-1),concentration 50 ppm,on a wild Mongolian gerbil population.The one-off contraceptive treatment was compared with a control group using a semi-monthly live trapping method in the Ordos Semi-desert Grassland Region of Inner Mongolia.The results show that juveniles were not recruited in spring in the treatment group.Ratios of juveniles in the control and treatment groups showed significant semi-monthly differences from spring to summer(one-way ANOVA,F_(2,14)=7.53,P<0.05).Between both groups,annual fluctuations of juvenile and total population densities were significantly different respectively(F_(2,14)=4.64,P<0.05;F_(2,18)=7.72,P<0.05).The contraceptive EP-1 delayed the normal reproductive pattern of Mongolian gerbil populations.This suppressed birth rates of gerbil populations,reduced their densities,and changed their age structures.The period of EP-1 baiting should be extended but it could be an ideal method for controlling Mongolian gerbil populations during each breeding season.
基金the support of the National Natural Science of China(Grant No.51878660)the National Natural Science of China(Grant No.51608527)the Natural Science of Jiangsu Province(Grant No.BK20191330).
文摘With the expansion of cities and the emergence of various urban problems,urban underground space has been developed as a solution.In China’s urban transition context,there is a need for the development of underground space in urban built-up areas.In this casestudy of the central city of Nanjing,we used spatial analysis and statistical methods to characterize the underground space use of urban built-up areas from a dynamic spatiotemporal perspective.We first analyzed the relationship between the population distribution and the underground space use of the central city of Nanjing based on a Baidu heat map,which can reflect the real-time population distribution,and then,we explored the spatiotemporal characteristics and spatial structure of the underground space use in urban built-up areas.The analysis results provide a reference for planning to improve and optimize the layout of underground space in the central city of Nanjing and,more generally,for the stock-type planning of underground space in urban built-up areas.
基金supported by the National Natural Science Foundation of China(Grant No. 30671587)the Programme for Introducing Talents of Discipline to Universities(Grant No.B07045)+1 种基金the Doctorial Innovation Fund of Southwest University(Grant No.Kb2009019)supported by grants from the U.S.National Science Foundation(Grant Nos.0531769, 0531626,and DEB-0212910)
文摘The silkworm,Bombyx mori,played an important role in the old Silk Road that connected ancient Asia and Europe.However,to date,there have been few studies of the origins and domestication of this species using molecular methods.In this study,DNA sequences of mitochondrial and nuclear loci were used to infer the phylogeny and evolutionary history of the domesticated silkworm and its relatives.All of the phylogenetic analyses indicated a close relationship between the domesticated silkworm and the Chinese wild silkworm.Domestication was estimated to have occurred about 4100 years ago(ya),and the radiation of the different geographic strains of B.mori about 2000 ya.The Chinese wild silkworm and the Japanese wild silkworm split about 23600 ya.These estimates are in good agreement with the fossil evidence and historical records.In addition,we show that the domesticated silkworm experienced a population expansion around 1000 ya.The divergence times and the population dynamics of silkworms presented in this study will be useful for studies of lepidopteran phylogenetics,in the genetic analysis of domestic animals,and for understanding the spread of human civilizations.
基金supported by the National Natural Science Foundation of China(31870511,41901134,U2003214)High-level Scientific Research Foundation for Talent Introduction in Xinjiang,and the Youth Innovation Promotion Association of the Chinese Academy of Sciences(2020437).
文摘The rapid uplift of the Qinghai-Tibet Plateau and its aridification has significantly affected the distribution and community structure of the plants in these regions.However,most of the studies have focussed on vascular plants,and it has been unclear whether bryophytes,which are haploid plants,had similar historical population dynamics to other vascular plants during the dramatic geological and climatic environment changes of the Quaternary.This study used Syntrichia caninervis Mitt as the research object and investigated its genetic variation,differentiation and population dynamic history in China.We genotyped 27 populations throughout the distributional range of S.caninervis using two chloroplast DNA regions and 19 nuclear microsatellite loci and supplemented these data with ecological niche modelling of the potential distribution areas from the last interglacial period.The results showed that genetic data consistently identified three clades:the Qinghai-Tibet Plateau,Pamir Plateau-TienShan and Central Asia.The genetic variation of Syntrichia caninervis mainly occurred within populations and in the populations within a specific region.However,there was a significant gene exchange between the different regions.S.caninervis may have expanded during the glacial period and shrank during the interglacial period.This study provides new evidence for the dynamic population history of drought-tolerant bryophytes in response to severe environmental changes during the Quaternary glacial and interglacial cycles.
