Pseudodendrothrips mori is a serious pest to mulberry trees and its infestation affects the qualitative and quantitative characteristics of mulberry leaves consumed by silkworm. The spatial distribution of mulberry th...Pseudodendrothrips mori is a serious pest to mulberry trees and its infestation affects the qualitative and quantitative characteristics of mulberry leaves consumed by silkworm. The spatial distribution of mulberry thrips within plant and orchard was assessed using Taylor＇s power law and Morisita＇s index of dispersion. The results showed that P.mori populations were localized in certain parts of the trees and fields. Distribution of thrips within plant showed that the larval instars were located on lower canopy （leaves 5-10 from top） of trees but adults preferred the upper canopy （leaves 1-5 from top）. The thrips density did not vary significantly among the leaf direction inside the trees. The thrips tended to be more accumulated on the trees located in East, South and North than in Center and West of orchard. The distributions of P.mori adults and larvae on the leaves were aggregated.展开更多
The total biomass of a stand is an indicator of stand productivity and is closely related to the density of plants. According to the self-thinning law, mean individual biomass follows a negative power law with plant d...The total biomass of a stand is an indicator of stand productivity and is closely related to the density of plants. According to the self-thinning law, mean individual biomass follows a negative power law with plant density. If the variance of individual biomass is constant, we can expect increased stand productivity with increasing plant density. However, Taylor's power law(TPL) that relates the variance and the mean of many biological measures(e.g. bilateral areal differences of a leaf, plant biomass atdifferent times, developmental rates at different temperatures, population densities on different spatial or temporal scales), affects the estimate of stand productivity when it is defined as the total biomass of large plants in a stand.Because the variance of individual biomass decreases faster than mean individual biomass, differences in individual biomass decline with increasing density, leading to more homogeneous timbers of greater economic value. We tested whether TPL in plant biomass holds for different species and whether the variance of individual biomass changes faster than the mean with increasing stand density.The height, ground diameter and fresh weight of 50 bamboo species were measured in 50 stands ranging from 1 m by 1 m to 30 m by 30 m to ensure more than 150 bamboos in every stand. We separately examined TPL in height,ground diameter, and weight, and found that TPL holds for all three biological measures, with the relationship strongest for weight. Using analysis of covariance to compare the regression slopes of logarithmic mean and variance against the logarithm of density, we found that the variance in individual biomass declined faster than the mean with increasing density. This suggests that dense planting reduced mean individual biomass but homogenized individual biomass. Thus, there exists a trade-off between effective stand productivity and stand density for optimal forest management. Sparse planting leads to large variation in individual biomass, whereas dense planting reduces mean indiv展开更多
Introduction:According to the empirical regularity called Taylor’s law,the variance of population density in samples of populations is a power of the mean population density.The exponent is often between 1 and 2.Our ...Introduction:According to the empirical regularity called Taylor’s law,the variance of population density in samples of populations is a power of the mean population density.The exponent is often between 1 and 2.Our experiments investigated how genetics,evolution,and environment shape Taylor’s law.Methods:Genetically different strains(wild type and hypermutator)of the bacterium Pseudomonas fluorescens evolved and were assayed under different environmental conditions(with and without antibiotic rifampicin and bacteriophage SBW252,separately and in combination).Results:Experimental treatments altered the exponent b,but not the power law form,of the relation between variance and mean population density.Bacterial populations treated only with rifampicin had a narrow range of mean population densities and exponent b=5.43.Populations exposed to rifampicin plus phage had b=1.51.In ancestral,control,and phage-exposed populations,mean abundance varied widely and b was not significantly different from 2.Evolutionary factors(mutation rate,selection)and ecological factors(abiotic,biotic)jointly influenced b.Conclusions:Taylor’s power law relationship accurately and robustly described variance as a function of mean population density,with overall exponent b=1.89.These and other experiments with different factors acting on bacterial population size support the relevance of models that predict‘universal’patterns of fluctuation scaling.展开更多
Sandpile phenomena in dynamic systems in the vicinity of criticality always appeal to a sudden break of stability with avalanches of different sizes due to minor perturbations. We can view the intervention of the Cent...Sandpile phenomena in dynamic systems in the vicinity of criticality always appeal to a sudden break of stability with avalanches of different sizes due to minor perturbations. We can view the intervention of the Central Banks on the rate of interest as a perturbation of the economic system. It is an induced perturbation to a system that fare in vicinity of criticality according to the conditions of stability embedded in the equations of the neoclassical model. An alternative reading of the Taylor Rule is proposed in combination with the Sandpile paradigm to give an account of the economic crisis as an event like an avalanche, that can be triggered by a perturbation, as is the intervention of the Central Bank on the interest rate.展开更多
A new idea on how to conceptually interpret the so-called Taylor’s power law for ecological communities is presented. The core of our approach is based on nonextensive/nonlinear statistical concepts, which are shown ...A new idea on how to conceptually interpret the so-called Taylor’s power law for ecological communities is presented. The core of our approach is based on nonextensive/nonlinear statistical concepts, which are shown to be at the genesis of all power laws, particularly when a system is constituted by long-range interacting elements. In this context, the ubiquity of the Taylor’s power law is discussed and addressed by showing that long-range interactions are at the heart of the internal dynamics of populations.展开更多
文摘Pseudodendrothrips mori is a serious pest to mulberry trees and its infestation affects the qualitative and quantitative characteristics of mulberry leaves consumed by silkworm. The spatial distribution of mulberry thrips within plant and orchard was assessed using Taylor＇s power law and Morisita＇s index of dispersion. The results showed that P.mori populations were localized in certain parts of the trees and fields. Distribution of thrips within plant showed that the larval instars were located on lower canopy （leaves 5-10 from top） of trees but adults preferred the upper canopy （leaves 1-5 from top）. The thrips density did not vary significantly among the leaf direction inside the trees. The thrips tended to be more accumulated on the trees located in East, South and North than in Center and West of orchard. The distributions of P.mori adults and larvae on the leaves were aggregated.
基金supported by the National Natural Science Foundation of China(31870575)the Key Project of National Science&Technology Ministry(No.2015BAD04B02)the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘The total biomass of a stand is an indicator of stand productivity and is closely related to the density of plants. According to the self-thinning law, mean individual biomass follows a negative power law with plant density. If the variance of individual biomass is constant, we can expect increased stand productivity with increasing plant density. However, Taylor's power law(TPL) that relates the variance and the mean of many biological measures(e.g. bilateral areal differences of a leaf, plant biomass atdifferent times, developmental rates at different temperatures, population densities on different spatial or temporal scales), affects the estimate of stand productivity when it is defined as the total biomass of large plants in a stand.Because the variance of individual biomass decreases faster than mean individual biomass, differences in individual biomass decline with increasing density, leading to more homogeneous timbers of greater economic value. We tested whether TPL in plant biomass holds for different species and whether the variance of individual biomass changes faster than the mean with increasing stand density.The height, ground diameter and fresh weight of 50 bamboo species were measured in 50 stands ranging from 1 m by 1 m to 30 m by 30 m to ensure more than 150 bamboos in every stand. We separately examined TPL in height,ground diameter, and weight, and found that TPL holds for all three biological measures, with the relationship strongest for weight. Using analysis of covariance to compare the regression slopes of logarithmic mean and variance against the logarithm of density, we found that the variance in individual biomass declined faster than the mean with increasing density. This suggests that dense planting reduced mean individual biomass but homogenized individual biomass. Thus, there exists a trade-off between effective stand productivity and stand density for optimal forest management. Sparse planting leads to large variation in individual biomass, whereas dense planting reduces mean indiv
基金The collection of the data analyzed here was funded by grants from the French Agence National de la Recherche(ANR)‘CoMute’(ANR-06-BLAN-0164)and‘EvolStress’(ANR-09-BLAN-099-01)MEH and OK were supported by grants‘EvolStress’(ANR-09-BLAN-099-01)and‘EvoRange’(ANR-09-PEXT-011)JEC was supported in part by grant EF-1038337 from the U.S.National Science Foundation,a grant from the region of Languedoc-Roussillon through the University of Montpellier 2,the assistance of Priscilla K.Rogerson,and the hospitality of Michael E.Hochberg and family during this work.Two referees provided helpful criticisms and suggestions.This is publication ISE-M 2012-032.
文摘Introduction:According to the empirical regularity called Taylor’s law,the variance of population density in samples of populations is a power of the mean population density.The exponent is often between 1 and 2.Our experiments investigated how genetics,evolution,and environment shape Taylor’s law.Methods:Genetically different strains(wild type and hypermutator)of the bacterium Pseudomonas fluorescens evolved and were assayed under different environmental conditions(with and without antibiotic rifampicin and bacteriophage SBW252,separately and in combination).Results:Experimental treatments altered the exponent b,but not the power law form,of the relation between variance and mean population density.Bacterial populations treated only with rifampicin had a narrow range of mean population densities and exponent b=5.43.Populations exposed to rifampicin plus phage had b=1.51.In ancestral,control,and phage-exposed populations,mean abundance varied widely and b was not significantly different from 2.Evolutionary factors(mutation rate,selection)and ecological factors(abiotic,biotic)jointly influenced b.Conclusions:Taylor’s power law relationship accurately and robustly described variance as a function of mean population density,with overall exponent b=1.89.These and other experiments with different factors acting on bacterial population size support the relevance of models that predict‘universal’patterns of fluctuation scaling.
文摘Sandpile phenomena in dynamic systems in the vicinity of criticality always appeal to a sudden break of stability with avalanches of different sizes due to minor perturbations. We can view the intervention of the Central Banks on the rate of interest as a perturbation of the economic system. It is an induced perturbation to a system that fare in vicinity of criticality according to the conditions of stability embedded in the equations of the neoclassical model. An alternative reading of the Taylor Rule is proposed in combination with the Sandpile paradigm to give an account of the economic crisis as an event like an avalanche, that can be triggered by a perturbation, as is the intervention of the Central Bank on the interest rate.
基金supported by grants from FAPESP,CAPES and CNPq,Brazilian funding agencies for the promotion of science.
文摘A new idea on how to conceptually interpret the so-called Taylor’s power law for ecological communities is presented. The core of our approach is based on nonextensive/nonlinear statistical concepts, which are shown to be at the genesis of all power laws, particularly when a system is constituted by long-range interacting elements. In this context, the ubiquity of the Taylor’s power law is discussed and addressed by showing that long-range interactions are at the heart of the internal dynamics of populations.
