81 resultados para niche partitioning
Resumo:
In this paper, as an extension of minimum unsatisfied linear relations problem (MIN ULR), the minimum unsatisfied relations (MIN UR) problem is investigated. A triangle evolution algorithm with archiving and niche techniques is proposed for MIN UR problem. Different with algorithms in literature, it solves MIN problem directly, rather than transforming it into many sub-problems. The proposed algorithm is also applicable for the special case of MIN UR, in which it involves some mandatory relations. Numerical results show that the algorithm is effective for MIN UR problem and it outperforms Sadegh's algorithm in sense of the resulted minimum inconsistency number, even though the test problems are linear.
Resumo:
Gaseous and particulate semi volatile carbonyls have been measured in urban air using an annular denuder sampling system. Three dicarbonyls, five aliphatic aldehydes and two hydroxy carbonyls were observed. Concentrations of other biogenic and anthropogenic volatile organic compounds (VOCs), SO2, CO, NO2 and particle concentration were also measured. Estimated gas-aerosol equilibrium constants for the carbonyls showed an inverse correlation with the concentrations of anthropogenic pollutants such as benzene, isopentane and SO2. This suggests that the increase in the fraction of non-polar anthropogenic particles in the atmosphere could change the average property of the ambient aerosols and drive the gas particle equilibrium of the carbonyls to the gas phase. This trend is uncommon in remote forest air. In this study, we examined the factors controlling the equilibrium in the polluted atmosphere and show that there is a difference in gas-aerosol partition between polluted and clean air.
Resumo:
The partitioning behavior of four amino acids, cysteine, phenylalanine, methionine, and lysine in 15 aqueous two-phase systems (ATPSs) with different polyethylene glycol (PEG) molecular weights and phosphate buffers has been studied in the present paper. The phase diagrams of the systems are investigated together with the effect of the PEG molecular weight and pH of the phosphate solutions. The composition of these systems and some parameters such as density and refractive index are determined. The influences of salts in ATPSs, side chain structure of the amino acids, pH of ATPSs, and the PEG molecular weight on the distribution ratios of the amino acids have been studied. This work is useful for the purification of amino acids and the separation of some proteins whose main surface exposed amino acid residues are these four amino acids, respectively.
Resumo:
The effects of feeding level on growth, retention efficiency, faeces production and energy partitioning of redlip mullet were studied. A practical diet was used and fed at six levels from starvation, 1%, 2%, 3%, 4% of body weight (BW) to satiation for 3 weeks. The temperature was kept at 24 +/- 1 degrees C. Reducing the feeding amount resulted in significantly lower weight gain, and retention efficiency was significantly affected by feeding levels and attained the maximum at maximum feeding intake. Feeding 2% BW was the minimum required for fish to maintain growth. Fish carcass composition under different feeding levels could be divided into three groups: (1) starvation and FL1; (2) FL2 and FL3 and (3) FL4 and satiation, with significant differences among the groups but no differences in the groups except that ash content remained at constant value. Body composition of fish of group 2 was close to initial fish. The thermal-unit coefficient was 0.0381 at satiation, and significantly increased with increasing feeding levels. In order to accurately estimate basal metabolism (HeE), another trial on the relationship between HeE (kJ) and BW (g) was carried out. An exponential curve as HeE=0.1255BW(0.8386) explained this relationship. Intake energy (IE) increased from 11.30 to 63.08 kJ per fish, matching with different feeding levels. Energy allocated to growth of IE decreased with reducing feeding amount. There was a linear relationship between metabolism energy and retention energy in percentage.
Resumo:
Based on surface energy flux data measured by eddy covariance methods from China Flux in alpine swamp meadow of the Qinghai Tibetan Plateau in 2005, the daily and seasonal dynamic of surface energy fluxes and their partitioning, as well as abiotic factors effects were analyzed. The results suggested that LE (Latent heat flux) was the largest consumer of the incoming energy. Rn (Net radiation flux) and LE showed clear seasonal variations in sharp hump and up to their maximums in August and July, respectively. H (Sensible heat flux) increased to its peak in August whereafter declined slowly. Precipitation could reduce the components of surface energy. As to Rn and LE, their correlations with abiotic factors were evident while it was not significant in H. Average EBR (Energy balance ratio) was 50.7 %, which was much larger in growing season than non-growing season.
Resumo:
Summer diets of two sympatric raptors Upland Buzzards (Buteo hemilasius Temminck et Schlegel) and Eurasian Eagle Owls (Bubo bubo L. subsp. Hemachalana Hume) were studied in an alpine meadow (3250 m a.s.l.) on Qinghai-Tibet Plateau, China. Root voles Microtus oeconomus Pallas, plateau pikas Ochotona curzoniae Hodgson, Gansu pikas O. cansus Lyon and plateau zokors Myospalax baileyi Thomas were the main diet components of Upland Buzzards as identified through the pellets analysis with the frequency of 57, 20, 19 and 4%, respectively. The four rodent species also were the main diet components of Eurasian Eagle Owls basing on the pellets and prey leftovers analysis with the frequency of 53, 26, 13 and 5%, respectively. The food niche breadth indexes of Upland Buzzards and Eurasian Eagle Owls were 1.60 and 1.77 respectively (higher value of the index means the food niche of the raptor is broader), and the diet overlap index of the two raptors was larger (C-ue = 0.90) (the index range from 0 - no overlap - to I - complete overlap). It means that the diets of Upland Buzzards and Eurasian Eagle Owls were similar (Two Related Samples Test, Z = -0.752, P = 0.452). The classical resource partitioning theory can not explain the coexistence of Upland Buzzards and Eurasian Eagle Owls in alpine meadows of Qinghai-Tibet Plateau. However, differences in body size, predation mode and activity rhythm between Upland Buzzards and Eurasian Eagle Owls may explain the coexistence of these two sympatric raptors.
Resumo:
囊瓣芹属Pternopetalum Franchet是伞形科Apiaceae/Umbelliferae芹亚科Apioideae芹族Apieae重要成员。全属包括约32个分类群(包括变种),分布于南朝鲜、日本、中国的西南部和邻近的喜马拉雅地区,中国西南部的横断山区是其多样性中心。典型的东亚特有格局和对东亚亚热带森林环境的偏爱是其东亚区系故有份子的特征。 基于19个标本馆标本材料、野外调查以及相应的实验证据,本博士论文从三个研究主题对囊瓣芹属展开了全面而系统的研究。一是通过标本观察和野外调查,利用标本管理系统BRAHMS和表型分析软件包DELTA系统,完成了囊瓣芹属的世界性分类修订;二是基于上述的分类方案,选择伞形科其它属的44个种作为参考性类群(Reference taxa),利用Winclada, NONA和MESQUITE软件包开展了分支系统学研究;三是基于坐标化的点分布数据,利用DIVA-GIS系统的生态位模型,进行潜在分布预测和生态地理分布特征的分析。研究的主要初步结论如下: 一、分类修订 根据对19个标本馆标本材料(包括85个模式采集)的考证,以及对云南、四川、贵州等地野外居群的观察,结合DELTA系统的表型分析,本研究确认囊瓣芹属包含14个种,提出了14个新异名,属下分为东亚囊瓣芹组Sect. I. Pteridophyllae H. Wolff和囊瓣芹组Sect. II. Pternopetalum H. Wolff两个组的分类方案。前者包括东亚囊瓣芹P. tanakae (Sav. & Franchet) Hand.-Mazz.、高山囊瓣芹P. subalpinum Hand.-Mazz.、洱源囊瓣芹P. molle (Franchet) Hand.-Mazz.等5个种;后者包括五匹青P. vulgare (Dunn) Hand.-Mazz.、囊瓣芹P. davidii Franchet和澜沧囊瓣芹P. delavayi (Franchet) Hand.-Mazz.等9个种。萼齿、花柱基、和花柱的形态是区别两个组比较好的形态学特征。叶的着生位置、最终末回裂片的形状(是否异形)、分裂回数以及伞形花序着生的位置和果棱表面的附属构造是种间识别有用的检索特征。 二、系统发育分析 根据如上的14个种的分类方案,另外选取了伞形科小芹属Sinocarum H. Wolff、丝瓣芹属Acronema Falc. ex Edgew.和鸭儿芹属Cryptotaenia L.等10个属共44种作为参考类群,基于63个广义形态学性状和58个种的形态学矩阵,利用最大简约法对囊瓣芹属进行了分支分析。结果表明,囊瓣芹属的14个种与日本特有单型的仙洞草Chamaele decumbens (Thunb.)Makino.形成一个单独分支,处于分支图的基部位置。表明囊瓣芹属与鸭儿芹属有较近的亲缘关系。长枝吸引可能是造成Chamaele Miq.与东亚囊瓣芹分支的非正常聚合的原因。囊瓣芹属可能是单系内群,但它与Chamaele Miq.属间关系需要进一步研究。属下形成以五匹青P. vulgare和东亚囊瓣芹P. tanakae为代表的两个主干演化线。分支进化(Cladogenesis)在两个主干演化线形成了形态和地理上对称分布的“种对”。根据形态特征的变异和地理分布,这些“种对”分为三种类型:1、形态上多变而地理上广布的类型,以东亚囊瓣芹P. tanakae和五匹青P. vulgare为代表;2、形态上稳定地理上狭域特有的类型,以薄叶囊瓣芹P. leptophyllum (Dunn)Hand.-Mazz. 和川鄂囊瓣芹P. rosthornii (Diels) Hand.-Mazz.为代表;3、形态上趋同而多变,地理分布上几乎完全重叠的类型,以洱源囊瓣芹P. molle和澜沧囊瓣芹P. delavayi为代表。 性状状态的分析显示,属下形态特征的趋异具有较强的同朔性。不等长的伞辐和花梗,以及囊状的花瓣基部三个形态学特征可以标识包括仙洞草在内的囊瓣芹分支。祖征状态的重建表明,东亚囊瓣芹分支相对保留了更多的祖征,是属下相对原始的类型;五匹青分支是后期生境需求的特化,适应潮湿和荫蔽环境的衍生类型。 三、生态地理分布 基于1128个坐标化的点分布数据和生态位模型,利用地理信息系统软件包DIVA-GIS对囊瓣芹属的物种多样性、现代地理分布、潜在分布进行了分析。结果表明,二郎山-峨眉山地区以及重庆金佛山及其临近地区是囊瓣芹属的两个主要的多样性中心。分布区内局部尺度上的异常性多样性(Diversity abnormalies)可能有两个来源:一是高的异质性生境条件下物种形成速率的差异;二是中国西南山地的“冰原岛峰效应”(Nunataks),比如峨眉山和金佛山,对属的早期演化线成员所起到的“避难所”(Refuge)的作用。 所预测的潜在分布范围与观察到的地理分布范围是一致的,说明对特化的气候忍耐性是限制囊瓣芹属物种地理分布的主要因素。温度和降水的季节性变化对囊瓣芹属代表中的地理分布限制作用比较大。亚热带-高山针阔常绿林是属下物种比较适宜的生境。属的地理分布可能形成于中新世以后,生态位的保守性是解释囊瓣芹属东亚本土就地分化和多样化的原因。属的分布范围的形成可能经历了一个早期南退西进的过程,后期分布范围变化可能主要是东西方向上的迁移和扩展。喜马拉雅—横断山—峨眉山/金佛山/神农架—日本、南朝鲜一线是囊瓣芹属多样化过程中分布范围东西延伸的重要通道。喜马拉雅—中国西南—日本朝鲜亚热带森林植被的完整性和连续性是囊瓣芹属演化和分布区形成的基本条件。
Resumo:
根据物种的分布信息结合环境因子估计物种的分布区对珍稀濒危物种的保护有着重要的意义。白豆杉Pseudotaxus chienii为第三纪孑遗植物,我国东南部地区特有,分布区狭窄。本文通过对白豆杉的标本记录研究它的地理分布,找出影响其分布的关键因子并对其潜在分布区进行估计,并解释其分布区形成的原因。全球升温将对物种分布造成重要影响,通过温度升高情况下2100年的气候数据模拟白豆杉未来的潜在分布区,估计温度升高对白豆杉的影响,将对白豆杉的保护有着重要的意义。 根据白豆杉的标本信息结合Diva-Gis软件对白豆杉的地理分布进行研究。以海拔图层和植被图层为底图对白豆杉的分布格局进行研究,并对白豆杉种群的多度进行统计分析。用Diva-Gis软件的气候数据提取功能提取白豆杉分布点的气候信息,并运用主成分分析对影响白豆杉分布的气候因子进行分析,找出影响白豆杉分布的主要环境因子。根据白豆杉的分布信息和气候数据,运用Diva-Gis内嵌的BIOCLIM模型和DOMAIN模型对白豆杉在不同气候条件下的潜在分布区进行估计,评价温度升高对白豆杉分布区的影响。 白豆杉分布格局研究结果表明,白豆杉分布在我国东南部地区中低海拔山区,白豆杉的分布和植被类型及海拔有着密切的关系。白豆杉的分布与海拔的关系表现为,由东到西,分布的最低海拔升高,海拔范围缩小。白豆杉分布地的植被类型为常绿灌木林,常绿阔叶林及针、阔叶混交林。白豆杉由东向西的海拔变化趋势与植被类型的由东向西的海拔变化趋势相一致。PCA分析结果表明白豆杉的分布与温度相关因子有着密切的关系。 现在气候对潜在分布区的估计表明,白豆杉的潜在分布区散布于浙、闽、粤、赣、湘,桂及黔几省各自交界之处即从浙江南部山区沿武夷山山系至南岭山系(向北到沿湘赣交界的罗宵山系)至大瑶山山系(向北沿雪峰山)。潜在分布区南部有三处分布的热点地区,即浙江南部、湖南南部和广西北部地区。三个主要分布区之间仅有有星散的潜在分布区存在,或没有潜在分布区出现,处在一种高度的隔离状态。造成这种潜在分布格局形成的原因可能有二,一是第四纪冰期的到来使白豆杉的分布区向南迁移,局部性气候的变化和地质变化可能导致了部分白豆杉的生境的消失,从而使得原来连续的分布区破碎化,形成了现在的星散分布;二是白豆杉的潜在分布区预测结果与中国东南部地区的山脉走势非常一致,山脉地带小生境多样化能够为白豆杉在垂直地带上的迁移提供更大的可能性。 未来气候数据对白都杉的潜在分布区估计表明,温度升高后白豆杉最适生分布区显著缩小。白豆杉的潜在分布区的地理分布格局发生了明显的变化,原来在南部的适生区明显缩小,星散程度更高。除已知的分布地外,在江西西南部武夷山、南岭山脉的湖南、广西、广东三省交界的地方都是白豆杉的适生区。江西和湖南交界的罗宵山山脉北部到井冈山都有白豆杉分布可能性较大,可以作为野外调查的重点地区。气候变化会使白豆杉在浙江、湖南南部的最适生境破碎化从而影响白豆杉的分布。生境保护对白豆杉的保护起着关键作用。
Resumo:
在北京东灵山地区以辽东栎(Quercus liaotungensis Koidz.)林群落为主要对象,研究了辽东栎种群和主要伴生种的空间格局、种间联结以及辽东栎种子雨的时间格局,井对空间格局的表达方法进行尝试性的探讨。 对辽东栎林群落中主要乔木树种辽东栎、大叶白蜡(Fraxinus thynchophylla)和五角枫(Acer mono)种群空间格局与动态的考察结果显示:各种群大多表现出聚集分布的趋势;辽东栎种群在各个龄级层均显示出较强优势,但种群内竞争激烈,龄级结构相对稳定;人叶白蜡的幼苗对环境适应能力较强,在成熟林中呈现出较五角枫种群更明显的增长型趋势:幼林中3个种群均呈衰退型趋势。 种间联结性的测定结果较好地反映了植物对环境的适应性,用关联分析法作出的树状图利用临界种将样方划分为若干组,体现出小生境之间的差异,反映了植物对其生境亦具有一定指示作用。 辽东栎种子雨的时间格局研究结果表明:种群种子雨密度随时间的变化呈正态分布趋势,种群水平利个体水平的种子雨累积随时间变化均符台Logistic曲线,具有很高的相关性。 空间格局表达方法的探讨显示:可以用集合论的方法对数学模型进行形象表达。