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Conservation priority of global Galliformes species based on phylogenetic diversity

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Integrative Zoology 2014年第3期9卷 340-348页

作者： youhua chen Department of Zoology University of British ColumbiaVancouverBCCanada Department of Renewable Resources University of AlbertaEdmontonAB T6G 2H1Canada

In this study,based on phylogenetic diversity(PD),I develop a conservation strategy for Galliformes species around the world.A cladogram of 197 Galliformes species derived from a previous study was used for calculating PD *** length is an important aspect of the phylogenetic information a tree can convey,but 2 traditionally-used metrics,the number of phylogenetic groups to which a taxon belongs(I)and the proportion that each taxon contributes to the total diversity of the group(W),are fully node-based and do not take branch length into ***,to measure PD more appropriately,I combined a branch-related metric,pendant edge(P),in addition to I and W.A final combined rank for Galliformes species was obtained by summing the ranks of the 3 *** results showed that the 5%top priority species for conserving evolutionary potential were Galloperdix lunulata,Haematortyx sanguiniceps,Margaroperdix madagarensis,Syrmaticus soemmerringii,Coturnix pectoralis,Polyplectron napoleonis,Alectoris melanocephala,Xenoperdix udzungwensis,Afropavo congensis and Syrmaticus *** current species priority ranking based on pylogenetic diversity and the official International Union for Conservation of Nature(IUCN)ranking of Galliformes species was significantly correlated when considering the 5 categories of IUCN(critical endangered,endangered,vulnerable,near threatened and least concern).This indicated the feasibility of introducing the PD index into the network of IUCN regional Red List *** 5%top priority countries selected using the complementarity principle possessing diversified Galliformes genetic resources were China,Indonesia,Mexico,India,Colombia,Australia,Brazil,Angola,Congo and Japan(in descending order).China,Indonesia,Mexico,Brazil,India and Colombia are consistently selected among the 4 top priority sets of richness,rarity,endemicity and *** result indicated that the priority result from PD is highly congruent with conventio

关键词： complementarity conservation priority evolutionary history IUCN Red List

On the historical biogeography of global Galliformes:ancestral range and diversification patterns

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Chinese Birds 2014年第1期5卷 15-20页

作者： youhua chen Department of Renewable Resources University of Alberta Edmonton T6G 2H1Canada

Background: In this study, the ancestral distributional ranges and the tempo of diversification patterns of global Galliformes were ***: Different diversification models characterizing possible tempo patterns were fitted and compared onto the phylogenetic tree for the 197 Galliforme species, consisting of a constant-speciation and constant-extinction model(CONSTANT), a decreasing-speciation and constant-extinction model(SPVAR), a constant-speciation and increasing-extinction model(EXVAR) and a decreasing-speciation and increasing-extinction model(BOTHVAR).Ancestral range reconstruction was conducted using the dispersal-extinction-cladogenesis ***: A constant-diversification-rate(CONSTANT) model best quantified the historical speciation patterns of this avian assemblage through model selection. Clade age and species richness are significantly and positively correlated. The most recent common ancestor for Galliformes species was originally found in the disjunctive regions between Southeast Asia and North America. High-frequency dispersal events were identified across the whole evolutionary ***: The constant diversification rate for global Galliforme species implied that there were no diversification rate-shifting trends for Galliformes species. The present study may contribute to the understanding of the ecology and diversity patterns of Galliformes from the perspective of historical biogeography, although some limitations existed.

关键词： Game birds Macro-evolution Rate shifting Zoogeography Phylogenetics

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Does the diversification rate of endemic birds of China's Mainland follow abrupt,gradual shifting or constant patterns?

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Integrative Zoology 2017年第2期12卷 165-171页

作者： youhua chen Department of Renewable Resources University of AlbertaEdmontonCanada

In this brief report,time-varying(including both gradual and abrupt change)and time-constant diversification models are fitted on a phylogeny of endemic birds of China's Mainland to test the diversification patterns of endemic birds in the *** results show that phylogeny of endemic birds is best quantified by a constant-rate diversification model through model *** of the study are *** particular,ignorance of non-endemic taxa and the limited sampling of endemic taxa could influence the conclusions of the study.

关键词： adaptive evolution avian endemism diversification analysis macroevolution

An island biogeography model for beta diversity and endemism： The roles of speciation, extinction and dispersal

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International Journal of Biomathematics 2015年第1期8卷 137-148页

作者： youhua chen Department of Zoology University of British Columbia BC V6T 1Z4 Canada

A community composition island biogeography model was developed to explain and predict two community patterns （beta diversity and endemism） with the consideration of speciation, extinction and dispersal processes. Results showed that rate of speciation is positively and linearly associated with beta diversity and endemism, that is, increasing species rates typically could increase the percentage of both endemism and beta diversity. The influences of immigration and extinction rates on beta diversity and endemism are nonlinear, but with numerical simulation, I could observe that increasing extinction rates would lead to decreasing percentage of endemism and beta diversity. The role of immigration rate is very similar to that of speciation rate, having a positive relationship with beta diversity and endemism. Finally, I found that beta diversity is closely related to the percentage of endemism. The slope of this positive relationship is determined jointly by different combinations of speciation, extinction and immigration rates.

关键词： Island biogeography model composition patterns endemism turnover

Habitat suitability modeling of amphibian species in southern and central China:environmental correlates and potential richness mapping

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Science China(Life Sciences) 2013年第5期56卷 476-484页

作者： chen youhua Department of Zoology University of British ColumbiaVancouver V6T 1Z4Canada

Successful wildlife management must take into account suitable habitat areas. Information on the correlation between distribution ranges and environmental conditions would, therefore, improve the efficacy of in-situ conservation of wildlife. In this contribution, correlations between environmental factors and the distribution of 51 amphibians in southern and central China were investigated. Ecological niche factor analysis （ENFA） at a spatial resolution of 1°latitudexllongitude identified a mixture of climatic and habitat factors as important predictors of the occurrence of individual species. The aims of the present work were （i） to evaluate potential distributions of amphibians based on the suitability of areas; （ii） to identify the major environmental descriptors upon which they depend; and （iii） to identify areas of potential high richness that have been overlooked in available inventories. Most of the predicted species ranges of species covered the majority of southern and central China. Six richness hotspots were predicted, of which four have been described previously, but two overlooked （SE Fujian and SE Qinghai）. The prediction model was considered to be relatively accurate and it is recommended that these two new potential hotspots should be subjected to further evaluation and sampling efforts. Amphibians have high ecological preference for high humidity and precipitation, and low annual frost days. ENFA is a useful tool in wildlife conservation assessment because it is able to identify potential hotspots where studies on the correlations between environmental descriptors and the occurrence of particular species could be focused.

关键词： ecological niche factor analysis habitat suitability modeling amphibians China distributional areas

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Global potential distribution of an invasive species,the yellow crazy ant(Anoplolepis gracilipes)under climate change

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Integrative Zoology 2008年第3期3卷 166-175页

作者： youhua chen College of Life Sciences Wuhan UniversityWuhan CityChina

Changes to the Earth’s climate may affect the distribution of countless species. Understanding the potentialdistribution of known invasive species under an altered climate is vital to predicting impacts and developingmanagement policy. The present study employs ecological niche modeling to construct the global potential distributionrange of the yellow crazy ant (Anoplolepis gracilipes) using past, current and future climate *** modeling algorithms, GARP, BioClim and Environmental Distance, were used in a comparative *** from the models suggest firstly that this insect originated from south Asia, expanded into Europe and theninto Afrotropical regions, after which it formed its current distribution. Second, the invasive risk of A. gracilipesunder future climatic change scenarios will become greater because of an extension of suitable environmentalconditions in higher latitudes. Third, when compared to the GARP model, BioClim and Environmental Distancemodels were better at modeling a species’ ancestral distribution. These findings are discussed in light of thepredictive accuracy of these models.

关键词： Anoplolepis gracilipes BioClim ecological niche modeling Environmental Distance GARP

老龄化、养老金覆盖率与水平对养老金支付负担的影响研究

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河北大学学报（哲学社会科学版） 2025年第1期50卷 1-17页

作者：陈友华孙永健南京大学社会学院江苏南京210023 南京大学新闻传播学院江苏南京210023

人口老龄化是影响基础养老保险制度可持续性的关键因素。基于年龄移算法和生命表技术,以第六次与第七次全国人口普查数据为基础,测算2010-2030年中国领取养老金的老年人口规模、年限与资金规模。研究发现:由于老龄化程度加深与养老保险... 详细信息

人口老龄化是影响基础养老保险制度可持续性的关键因素。基于年龄移算法和生命表技术,以第六次与第七次全国人口普查数据为基础,测算2010-2030年中国领取养老金的老年人口规模、年限与资金规模。研究发现:由于老龄化程度加深与养老保险覆盖面扩大,中国领取养老金的老年人口规模持续扩大,从2010年的1.23亿人增加到2030年的3.32亿人。与此同时,中国养老金领取水平逐渐提高,养老金支付负担与日俱增,支出总额至少从2010年的13293.90亿元上涨至2030年的118933.19亿元。此外,由于老年人口余寿的显著延长,老年人领取养老金的年限也不断延长,从2010年的10.13年延长到2030年的19.92年,领取年限延长速度超过余寿延长速度。另外,养老金的支付负担还存在明显的性别与城乡差异。故而,提出落实延迟退休政策、慎重上调养老金替代率与养老金水平等参量变革措施、发展多支柱养老金模式、鼓励生育等结构改革举措,在人口与经济高质量发展中促进共同富裕。

关键词：人口老龄化养老金负担延迟退休共同富裕

On the mechanisms of the saltating motion of bedload

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International Journal of Sediment Research 2017年第1期32卷 53-59页

作者： youhua chen Yuchuan Bai Dong Xu State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin University Jinchang Water Conservancy Department

Saltation of sediment particles is an important pattern of bedload *** on force analysis for sediment particles,a Lagrangian model was proposed for the saltating motion of bedload in river flows,which was then solved with numerical *** results on the saltating trajectories neglecting particle rotation and turbulence effects compare fairly well with experimental *** mean values of the saltation parameters(saltation height,length and velocity) also agree well with the previous experimental *** on the numerical results,regression equations for the dimensionless saltation height,length and velocity were *** the numerically achieved characteristics of the sediment saltation,we also obtained mathematical expression for the sediment transport *** studies in this paper are significant for its contribution to mechanism of the bedload motion and the computation of sediment transport rate.

关键词： Bedload Saltation Numerical model Transport rate

OPTIMAL POLICY WITH A TOTAL ORDER QUANTITY COMMITMENT CONTRACT IN THE PRESENCE OF A SPOT MARKET

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Journal of Systems Science and Systems Engineering 2011年第1期20卷 25-42页

作者： Wei ZHANG youhua (Frank) chen Zhongsheng HUA Weili XUE School of Management University of Science and Technology of China Hefei China Department of Systems Engineering and Engineering Management The Chinese University of Hong Kong Shatin N. T. Hong Kong China Yurun Corp. Nanjing China

In this paper, the optimal policy is considered when the buyer faces two supply sources： one is the contract supplier from which the buyer orders over a specific contract period （say, a year） at a pre-agreed price, and the other is the spot market. However, when ordering from the contract supplier, the buyer must fulfill a pre-determined total order quantity, or the so-called definite total order quantity commitment, over the whole contract period. In other words, the commitment secures the buyer a fixed price but obliges him/her a total order quantity over the contract period. Although the spot market gives the buyer more flexibility in terms of order quantities, its prices are volatile. Such a combination of contract and spot procurements is often observed in practice. Within the contract period, there are multiple sub-periods, during each of which the buyer reviews the inventory, issues an individual order, and uses the on-hand inventory to meet the random demand. Thus, in each （ordering） period, the buyer will weigh between the current known spot price （by procuring from the spot market） and a lower future price （by waiting while consuming the remaining commitment）. An optimal dual ordering policy is characterized for each period, depending on the on-hand inventory level, the spot price, and the remaining commitment quantity. The optimal policy in each period is also shown to be independent of the contract price. Through a numerical study, the inventory cost is demonstrated to be （1） insensitive to the contract price when the total commitment quantity is lower than the total expected demand over the contract period and （2） non-increasing in the variability of spot prices.

关键词： Total ordering quantity commitment (TOQC) spot market procurement policy

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