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Epidemic time series similarity is related to geographic distance and age structure

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Infectious Disease Modelling 2022年第4期7卷 690-697页

作者： Tad A.Dallas Grant Foster Robert L.Richards Bret D.Elderd Department of Biological Sciences University of South CarolinaColumbiaSC29208USA Department of Biological Sciences Louisiana State UniversityBaton RougeLA70802USA

Objective:More similar locations may have similar infectious disease dynamics.There is clear overlap in putative causes for epidemic similarity,such as geographic distance,age structure,and population size.We compare the effects of these potential drivers on epidemic similarity compared to a baseline assumption that differences in the basic reproductive number(R0)will translate to differences in epidemic trajectories.Methods:Using COVID-19 case counts from United States counties,we explore the importance of geographic distance,population size differences,and age structure dissimilarity on resulting epidemic similarity.Results:We find clear effects of geographic space,age structure,population size,and R0 on epidemic similarity,but notably the effect of age structure was stronger than the baseline assumption that differences in R0 would be most related to epidemic similarity.Conclusions:Together,this highlights the role of spatial and demographic processes on SARS-CoV2 epidemics in the United States.

关键词： Epidemic similarity SARS-CoV2 age structure Distance decay

Genotypic Diversity Affects age structure of Tiller and Rhizome of Leymus chinensis Population,But Not age structure of Bud

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Phyton-International Journal of Experimental Botany 2023年第11期92卷 3163-3176页

作者： Chan Zhou Nini Xie Wenjun Rong Zhuo Zhang Linyou Lv Zhengwen Wang School of Life Science Liaoning UniversityShenyang110036China School of Life Science and Bioengineering Shenyang UniversityShenyang110044China Research Institute of Sand Control and Utilization Fuxin123000China State Key Laboratory of Forest and Soil Ecology Institute of Applied EcologyChinese Academy of SciencesShenyang110164China

The effect of genotypic diversity on the age structure and bud bank of the Leymus chinensis population has not yet been demonstrated.This experiment was designed to study the age structure of the tiller,rhizome,and bud of L.chinensis at genotypic diversity levels of 1,2,4,8,and 12.A total of 64 communities were established in this experiment,following the principle of randomized block experimental design.The results indicated that genotypic diversity had a significant or obviously significant effect on the cumulative length of rhizomes of 2a and 4a,dry matter accumulation of rhizomes of 1a and 2a,tiller number of 1a,tiller productivity of 3a,but had no significant effect age structure of buds.As the levels of genotypic diversity increased,the proportion of the cumulative length of rhizomes with 4a decreased and then increased,and dry matter accumulation of rhizomes with 1a and 2a gradually increased while the number of tillers with 1a gradually decreased,when the gradient of genotypic diversity increased.At the 1,2,4,8,and 12 genotype diversity levels,the number of tillers,the cumulative length of rhizomes,and dry matter accumulation in rhizomes and buds were all age structures of expanding type.However,tiller productivity was an expanding or stable age structure at levels of 1,2,4,8 genotypic diversity,while it was a declining age structure at the 12 genotype diversity gradient.An appropriate genotypic diversity is conducive to maintaining the growth and stability of the age structure of L.chinensis population,but too high a gradient of genotypic diversity can have a negative impact on the population age structure.This study provided that an appropriate number of genotypic diversity contributes to the stability of the population.

关键词： Genotypic diversity L.chinensis age structure population

age structure of a lizard along an elevational gradient reveals nonlinear lifespan patterns with altitude

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Current Zoology 2020年第4期66卷 373-382页

作者： Mar Comas Senda Reguera Francisco JZamora-Camacho Gregorio Moreno-Rueda Departamento de Zoologia Facultad de CienciasUniversidad de GranadaGranadaE-18071Spain Estacion Biologica de Donana(EBD-CSIC) Americo Vespucio 26SevillaE-41092Spain Department of Biological Sciences Dartmouth CollegeHanoverNHUSA

Lifespan is one of the main components of life history.Shorter lifespans can be expected in marginal habitats.However,in the case of ectotherms,lifespan typically increases with altitude,even though temperature-one of the main factors to determine ectotherms'life history-declines with elevation.This pattern can be explained by the fact that a shorter activity time favors survival.In this study,we analyzed how lifespan and other life-history traits of the lizard Psammodromus algirus vary along a 2,200 m elevational gradient in Sierra Nevada(SE Spain).Populations at inter-mediate altitudes(1,200-1,700 m),corresponding to the optimal habitat for this species,had the shortest lifespans,whereas populations inhabiting marginal habitats(at both low and at high altitudes)lived longest.Therefore,this lizard did not follow the typical pattern of ectotherms,as it also lived longer at the lower limit of its distribution,nor did it show a longer lifespan in areas with optimal habitats.These results might be explained by a complex combination of different gradients along the mountain,namely that activity time decreases with altitude whereas food availability increases.This could explain why lifespan was maximum at both high(limited activity time)and low(limited food availability)altitudes,resulting in similar lifespans in areas with contrasting environmental conditions.Our findings also indicated that reproductive investment and body condition increase with elevation,suggesting that alpine populations are locally adapted.

关键词： age structure elevation lite history longevity marginal habitats relative clutch mass

age structure of Two Species of Odorous Frogs(Odorrana margaretae and Odorrana grahami)

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Asian Herpetological Research 2021年第3期12卷 308-314页

作者： LIANJU YUAN MAOJUN ZHONG WENBO LIAO Key Laboratory of Southwest China Wildlife Resources Conservation(Ministry of Education) China West Normal UniversityNanchong 637009SichuanChina Key Laboratory of Artificial Propagation and Utilization in Anurans of Nanchong City China West Normal UniversityNanchong 637009SichuanChina Institute of Eco-adaptation in Amphibians and Reptiles China West Normal UniversityNanchong 637009SichuanChina

Variation in age structure and body size benefits are identified to understand the evolution of life history.Here,we estimated the age structure and body size of two species of odorous frogs(Odorrana margaretae and Odorrana grahami)by using skeletochronology.The ages at sexual maturity of O.grahami and O.margaretae in both sexes were 1 and 2 years,respectively.For both sexes,the maximum age observed in O.margaretae was six years.For O.grahami,the maximum age observed in males and females were 4 and 5 years,respectively.Males and females did not differ in mean age in the two species.The average body size of both species considerably differed between sexes,with females being larger than males.The body size of females was also larger than that of males when the effect of age was removed.We also found positive correlations between body size and age within each sex in O.margaretae,but only for female in O.grahami.The female-biased sexual size dimorphism of the two species suggested that fecundity selection for larger female size may increase the reproductive output.

关键词： age structure body size odorous frogs skeletochronology

age structure of Females in a Breeding Population of Echinotriton chinhaiensis(Caudata:Salamandridae) and Its Conservation Implication

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Asian Herpetological Research 2011年第2期2卷 91-96页

作者： Weizhao YANG Chang LIU Jianping JIANG Cheng LI Feng XIE Chengdu Institute of Biology Chinese Academy of Sciences The Graduate University of Chinese Academy of Sciences

Knowledge of life history is important for understanding possible connections to population declines. Here, we investigated the female age structure and fecundity of Echinotriton chinhaiensis, one of the most endangered salamanders in the world, using skeletochronology based on specimens collected in 2008 and 2009 from a population in Ruiyansi, northeast of Ningbo, Zhejiang, China. The results showed that most female salamanders were between 5 and 6 years of age, with the minimal reproductive age, predicted to be 3 years, and the clutch size correlated to the body size. We argue that both delayed attainment of sexual maturity and low fecundity make this species more vulnerable to extinction.

关键词： skeletochronology age structure sexual maturity fecundity clutch size

age structure in neutral theory resolves inconsistencies related to reproductive-size threshold

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Journal of Plant Ecology 2012年第1期5卷 64-71页

作者： James Rosindell Patrick A.Jansen Rampal S.Etienne Institute of Integrative and Comparative Biology Faculty of Biological SciencesUniversity of LeedsLeeds LS29JTWest YorkshireUK Institute of Bioinformatics and Evolutionary Studies University of IdahoMoscowID 83844USA Center for Tropical Forest Science Smithsonian Tropical Research InstitutePO Box 0843-03092BalboaAnconRepublic of Panama Centre of Ecosystem Studies Wageningen UniversityPO Box 476700 AA Wageningenthe Netherlands Community and Conservation Ecology Centre for Ecological and Evolutionary StudiesUniversity of GroningenPO Box 111039700 CC Groningenthe Netherlands

Aims Neutral theory consists of a suite of models that assume ecological equivalence among individual organisms.They have been most commonly applied to tropical forest tree communities either as null models or as approximations.Neutral models typically only include reproductive adults;therefore,fitting to empirical tree community data requires defining a reproductive-size threshold,which for trees is usually set arbitrarily to a diameter at breast height(DBH)of 100 mm.The inevitable exclusion of some reproductive adults and inclusion of some saplings cause a non-random sampling bias in neutral model fits.Here,we investigate this problem and resolve it by introducing simple age structure into a neutral model.Methods We compared the performance and sensitivity of DBH threshold of three variants of a spatially explicit neutral model:the traditional model,a model incorporating random sampling and a model with two distinct age classes—reproductive adults and saplings.In the age-structured model,saplings are offspring from adults that disperse according to a Gaussian dispersal kernel around the adults.The only extra parameter is the ratio of adults to saplings,which is not a free parameter but directly measurable.We used species–area relationships(SARs)to explore the predicted effect of saplings on the species richness at different scales in our model.We then evaluated the three model variations to find the parameters required to maintain the observed level of species richness in the 50-ha plot on Barro Colorado Island(BCI).We repeated our analysis filtering the data at different minimum tree-size thresholds in order to find the effect this threshold has on our results.Lastly,we used empirical species–individual relationships(SIRs)to test the pre-existing hypothesis that environmental filtering is the primary cause of differences between the assemblage of saplings and that of adults on BCI.Important Findings Our age-structured neutral model was characterized by SARs that were insensitive to the presence of saplings at

关键词： neutral theory age structure sampling DBH

age structure AND SPATIAL PATTERN OF OLD-GROWTH KOREAN PINE FOREST IN XIAOXING'ANLING MOUNTAIN

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Journal of Northeast Forestry University 1991年第2期2卷 17-22页

作者： Ge Jianping Guo Haiyan Chen Dong Northeast Forestry University, Harbin Northeast Forestry University Harbin

Spatial pattern of trees, basal stem increment and height were examined in a 5.0 ha mixed deciduous/ Pinus koraiensis forest from October in 1984 to May in 1987. Conclusions arc as following: 1. Analysis of the age-structure of the korcan pine forest shows that it is different from general steady-state forest type. The lack of saplings and individuals in small-diameter class clearly indicates that regeneration is not continuous. Continuous regeneration depends on thinning of the canopy to form a gap. Similar-aged korcan pine seedings grow in these gaps. 2. The horizontal structure of the korcan pine is a mosaic of more or less even-aged groups of trees. The mosaic is a result of korcan pine by regeneration strategy. The aggregations of korcan pine of different ages overlaps to form a continuous population generation. As a results, the population is maintained in steady state.

关键词： Xiaoxing'anling age structure Spatial pattern Population Old-growth korean pine forest

Dynamics of an SIRS model with age structure and two delays

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International Journal of Biomathematics 2021年第7期14卷 145-162页

作者： Hongquan Sun Hong Li Jin Li Zhangsheng Zhu School of Mathematics and Physics Jiangsu University of Technology Changzhou 213001 P.R.China School of Science Jiuyjiang University Jiujiang 332005P.R.China

ln this paper,we propose and investigate an SlRS model with age structure and twodelays.Both the infected and the recovered individuals have age structure,the infectionrate(from the infective to the susceptible)and the immune loss rate(from the recoveredto the susceptible)are related to two independent time delays,respectively.We provethat the proposed age structured SIRS model is well-posed by using the Co-semigrouptheory.The basic reproduction number Ro is given,and the unique endemic equilib-rium exists when R_(0)>1,while the disease-free equilibrium always exists.A rigorousmathematical analysis for the stability of two equilibria is provided.The disease-freeequilibrium is local asymptotically stable if R_(0)1 and τl=0.Finally,we give numerical simulations toverify our results.

关键词： Infectious disease model SIRS model age structure delay stability

age structure and dynamics of Zoysia japonica module population

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Journal of Forestry Research 2005年第2期16卷 117-120页

作者： DAIBao-qing WANGYan ExperimentalCenterofShenyangNormalUniversity Shenyang110034P.R.China InstituteofAppliedEcology ChineseAcademyofSciencesShenyang110016PR.China

The age structure of the natural Zoysia japonica clonal population at QipanMountain in Huishan Scenic Spot of Shenyang, Liaoning Province, China was studied using themorphological method in 2003 and 2004. The dynamics of leaves were recorded and the dynamics oftiller and rhizome in the growing season were observed. The results indicated that the rhizomesformed in different years changed in color and rigidity. Its internodes produced in autumn becameshorter. The number of naked nodes changed with the tiller age. Rhizome and tiller characters wereused as a foundation for judging the ages of modules in this study. The longevity of tiller andrhizome was 3 years at most. At the beginning of the growing season, 2-year-old tillers and rhizomespredominated. Then 1-year-old tillers and rhizomes increased rapidly and became dominant in July.The proportion of buds to tillers on quantity was stable at about 30% in the mid-phase of thegrowing season and rose to about 50% in autumn. The seasonal dynamics of tiller, rhizome and bud wasvery important to guarantee the sustained existence of the Zoysia japonica population. The turnoverof modules was the mechanism of sustaining the rejuvenation of the Zoysiajaponica clonalpopulation.

关键词： zoysiajaponica module age structure dynamics