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1.
Friction of volar skin on wood is not proportional to load in human beings and prosimians, but to load raised to a fractional power. This meets theoretical expectations for the frictional characteristics of convex elastic surfaces. Although this enables small clawless primates to cling to steeper slopes and larger vertical supports than would otherwise be possible, the magnitude of the effect is not great enough to overcome the disadvantages of clawlessness in climbing vertical or steeply-sloping tree trunks and branches. In human subjects, friction appears to be more nearly proportional to load than in small prosimians used as experimental subjects. It is suggested that this is due to the fact that the small animals have discrete, elevated volar pads. Pad coalescence in large primates may be an adaptation for increasing the power to which load must be raised to become proportional to friction; increasing this exponent yields more friction per unit of adduction force on supports that are small relative to the animals' dimensions and weights.  相似文献   

2.
Subgroups within a population are often difficult to discover and describe except by subjective methods. In this study, cluster analysis (numerical taxonomy) methods were used on selected craniofacial measurements obtained from 308 North American White children of both sexes in the age range 6–18 to derive categories of skeletal facial types. Two different cluster analysis approaches were used in conjunction with a separate overall evaluation of facial balance, an independent measure of maxillo-mandibular relationship (AB/FOP), and a traditional classification (Angle). The categories derived rest on corroborative and overlapping evidence from each of those methods. The categories were examined to determine if it is possible to classify a sample by means of cluster analysis, the size and discreteness of each class, how they compare with the Angle classification of the same sample, and the percentage of individuals that may be identified unequivocally by this classification scheme. Five categories were obtained. Labeled Category A — Category E, they show some correspondence to the Angle Classes I, II, and III, but categories A, B, and C appear to be subgroups, heretofore undetected, of Angle Class II. Categories D and E correspond to Angle Classes I and III, respectively. The categories are more realistic and informative than the Angle classes. Each category is reported along with its distinguishing skeletal characteristics.  相似文献   

3.
大戟科植物分类的数值分析   总被引:5,自引:1,他引:5  
根据大戟科216个分类性状的分布,采用欧氏距离系数一类平均法对Webster(1994)广义大戟科49个族或亚族进行聚类分析。结果表明,现行的大戟科分类系统中,大多数族和亚族水平的分类基本合理,而Galearieae族的系统位置和五月茶族Antidesmeae等亚族的划分出现较大矛盾。该系统中未包含的方鼎木属Archileptopus,应与叶下珠族的Pseudolachnostylidillae亚族接近。  相似文献   

4.
中国栎属植物的数量分类研究   总被引:10,自引:1,他引:10  
在全面衡量中国栎属49种4变种性状特征的基础上,观测了25个定性性状和18个数量性状。通过聚类分析,可以将中国栎属分为5个特征明显的表征群,即5组:麻栎组(Section Aegilops)、槲栎组(Section Quercus)、高山栎组(Section Brachylepides)、巴东栎组(Section Engleriana)和橿子栎组(Section Echinolepides)。在主成分分析中,虽然性状的累积贡献率增长不明显,前3个主成分累积贡献率仅有50.4%,但结果仍然显示出和聚类分析同样的结果。说明栎属的分类性状仍存在主要方面,只不过在演化过程中由于性状变异的多样性,产生了多个不同的表征类群。分析结果对我们解决个别有疑问种的分类地位也有启示作用。因此,数量分类方法对解决栎属组间及种间的分类问题有重要的意义。  相似文献   

5.
中国薹草属黑穗薹草组的数量分类研究   总被引:1,自引:0,他引:1  
对中国薹草属黑穗薹草组Sect.Racemosae及外类群冻原薹草组Sect.Frigidae共20种3变种采用38个形态特征进行了数量分类研究。聚类分析结果表明,黑穗薹草组应是一个自然分类群;支持了《中国植物志》将两对相似种:乌拉草(Carer meyeriana)与红原薹草(Carer hongyuanensis)、膨囊薹草(Carex lehmanii)与五台山薹草(Carex montis-wutaii)分别处理为种的观点。主成分分析结果表明,本组的分类特征较为稳定与集中,本组主成分分析散点图与聚类分析的分类结果大致吻合,并表明有关小坚果、果囊、鳞片、主茎叶和苞片的性状在本组的分类中起到了主要作用。  相似文献   

6.
Thermodynamic taxonomy (ThT) is established from both a theoretical and pragmatical point of view. An application of thermodynamic taxonomy is given.  相似文献   

7.
本文对我国黑粉菌属(Ustilago)51个样本,选取33个形态学和生物学编码性状进行了类平均法的系统聚类分析。根据聚类分析结果,建议将我国黑粉菌属分为3个表观群(Phenons);茭白黑粉菌目前以放在黑粉菌属内为妥;还认为 Ustilago ocrearum 是 Ustilagokoenigiae 的变种;Ustilago kusanoi 是 Ustilago minima 的变种;Us(?)ilago aoenoe 和 Usti-lago nuda 是两个不同种。  相似文献   

8.
9.
通过对1500余份标本的测量和统计,结合文献和野外考察,选取了30个形态学性状,对卫矛属(Euonymus)刺果卫矛组(sect. Echinococcus)13个种进行了数量分类学分析。聚类分析结果表明,美国卫矛(E.americanus)和陈谋卫矛(E.chenmoui)的亲缘关系最近,不支持Blakelock将本组划分为两个系的观点。本组中系统位置有争议的物种:厚叶卫矛(E.hemsleyanus)与紫刺卫矛(E.angustatus)、棘刺卫矛(E.echinatus)和无柄卫矛(E.subsessilis)、刺猬卫矛(E.hystrix)和蒙自卫矛(E.mengtseanus)、刺果卫矛(E.acanthocarpus)和腾冲卫矛(E.tengyuehensis),在聚类图中显示出较远的亲缘关系,通过方差分析对这些物种间有较明显差异的性状进行进一步分析。结果表明,这些物种在叶尖角度、叶长、侧脉与主脉的夹角、花序梗长等性状上均具有显著差异。分析结果支持将蒙自卫矛与腾冲卫矛排除出刺果卫矛组,支持厚叶卫矛和紫刺卫矛作为独立的种,由于在交叉分布地域没有足够的研究资料,棘刺卫矛和无柄卫矛的系统位置有待进一步确认。因子分析结果表明,本实验所用性状间的独立性较强,叶长、侧脉与主脉的夹角、花序分支数、果实带刺的长度等18个性状在本组中具有重要的分类学意义。  相似文献   

10.
三种菟丝子的数值分类学   总被引:2,自引:0,他引:2  
选取33个形态学性状,应用不加权虎术平均配对法,对惧到的3种菟丝子的24个居群进行了数值分类学研究,结果表明:(1)日本菟丝子与大花菟丝子亲缘关系较近,两者与中国菟丝子之间关系较疏远,聚类结果献技Yuncker对菟丝子属的分类处理;(2)日本菟丝子和大花菟丝子种内都存在遗传多样性,根据聚类结果将日本菟丝子分成2个变种,将大花菟丝子分成3个变种。  相似文献   

11.
Enamel has been stripped from primate teeth (especially humans and ceboids) with special reference to the comparative form of the hypocone. Dentally reduced species show variable developments not always expected of a hypothetical ontogenetically prior stage.  相似文献   

12.
不休眠单胞锈菌等属的数量分类研究   总被引:1,自引:0,他引:1  
不休眠单胞锈菌属Maravalia是Arthur1922年建立的,对它的属上分类一直是有争议的。Dietel(1928)只根据M.albescens这一个种的性状,将Maravalia放在3Pucciniaceae中的Ravenlieae族;Mains(1939)建议将Maravalia放在Pucciniaceae中的Eriosporangieae,但他也承认Mavenelieae与Oliveae族中的一些属有较大相关性。Leppik(1972)将Maravalia与Chrysocelis一起组成Pucciniaceae下的一个新族Maravalieae,但是Maravalieae,没有得到  相似文献   

13.
This study aims to clarify the relationship of primate bony pelvic structure to locomotor habit. As with most of the postcranial skeleton, the pelvic bones of species within the Ceboidea and the Cercopithecoidea are remarkably similar visually except for variations in size. Yet there are substantial differences in locomotor pattern between the species in these taxa. I performed canonical analyses on a sample of 17 pelvic variables describing 22 primate species of the Ceboidea, the Cercopithecoidea, and the Hominoidea to discover which variables were significant in separating them into groups. In both analyses there was good separation of major taxa and additional separation of groups that differed in locomotor habit. The separation of colobine from cercopithecine monkeys was particularly consistent. In the analysis, including all 22 species, the variables given particular weight by the canonical analysis were the same as those traditionally used by anatomists for the same purpose. Specifically, breadth of the ischial tuberosity (reflecting presence or absence of ischial callosities) separated the Old from the New World monkeys. Breadth of the iliac tuberosity, in which man and to some extent other hominoids differ from other primates, and ilium height, in which man differs from other primates, were significant. Sagittal diameter of the pelvis was also substantially weighted. Having established that the technique would select variables of anatomical significance, the same method was applied to a study of monkeys only where the characteristics that differ between groups are not well established. Breadth of the ischial tuberosity was again important in separating the Ceboidea from the Cercopithecoidea. Discrimination of locomotor groups within these large divisions was brought about mainly by ischial length and the sagittal diameter of the pelvis. In studying these variables and their relationship to size in greater detail, it was found that among cercopithecoid monkeys, the colobines showed relatively lower values than did cercopithecines for both these dimensions. Atelines showed low values for ischial length but high values for the sagittal pelvic diameter. Biomechanical explanations of these observations are suggested.  相似文献   

14.
棕囊藻属的分类现状   总被引:8,自引:2,他引:8  
陈丽芬  章群  许忠能  刘宁宁  胡韧 《生态科学》2003,22(1):93-94,85
棕囊藻属藻类生活史复杂、地理差异显著、游动单细胞个体微小,至今尚无明确的分类标准。在目前已报道的9个种中,Sournia(1988)认为只有两个种比较可靠,即形成胶群体的P.pouchetii(sensu lato)(包括P.globosa)和不形成胶群体的P.scrobiculata;一些学者将P.puchetii(sensu lato)进一步细分成P.pouchetii(sensu stricto)、P.globosa,P.antarctica等3种,为方便起见,多数学者将形成胶群体的棕囊藻定名为P.pouchetii,或写成未定种的形式Phaeocystis sp.棕囊藻属分类的混乱制约了相关研究的深入,解决棕囊藻分类混乱问题有赖于新的技术和方法的使用。  相似文献   

15.
Numerical taxonomy of the wild bananas (Musa)   总被引:2,自引:0,他引:2  
  相似文献   

16.
药用鼠尾草属数值分类与丹参药材道地性   总被引:24,自引:0,他引:24  
运用数值分类方法,将鼠尾草属(SalviaL.)药用植物资源划分为3类:高山丹参类、低山丹参类和非丹参类。该结果为鼠尾草属植物分类鉴定、资源开发及丹参药材道地性研究提供了新的参考依据  相似文献   

17.
十五种叶形吸虫的数值分类研究   总被引:1,自引:0,他引:1  
刘家英  郎所 《动物学报》1992,38(1):17-22
本文对中国15种叶形吸虫成虫的12项成虫形态特征进行了聚类分析和主成分分析,结果表明:运用8种不同的聚类方法所得到的谱系分枝图基本一致,即15种叶形吸虫明显地可分为两大亚群,它们分别与Phyllodistomum和Catoptroides亚属相对应。主成分分析所得到的坐标定位图则进一步证实了这一结果,并且显示了在叶形属吸虫中,成虫体形因素、卵黄腺类型及生殖腺相互位置等特征是该属吸虫的主要分类依据。  相似文献   

18.
Although several investigations have been made from different viewpoints, the classification or interspecific relationships ofSaguinus still remain uncertain. In the present study, we applied multivariate analysis methods to dental measurements of part ofSaguinus populations of sufficient sample size and obtained the following conclusions.Saguinus can be classified into two main groups: one consists ofS. oedipus andS. leucopus, and the other ofS. fuscicollis, S. nigricollis, S. labiatus, andS. mystax. Concerning the former group, the two subspecies ofS. oedipus, S. o. oedipus, andS. o. geoffroyi, show a close affinity with each other and also a close relationship toS. leucopus, while the latter group consists of two subgroups of species, one includingS. fuscicollis andS. nigricollis, and the other includingS. labiatus andS. mystax. The biological distance betweenS. oedipus oedipus andS. o. geoffroyi is slightly larger than that between the pairs ofS. fuscicollis andS. nigricollis and ofS. labiatus andS. mystax. Factor analysis revealed significant factors which could explain the differences among the seven maleSaguinus populations. Taking all the results into account, it seems necessary to reconsider the phylogenetic relationships within the genusSaguinus.  相似文献   

19.
The incidence of agenesis and polygenesis in the primate dentition   总被引:1,自引:0,他引:1  
The incidence of dental agenesis and polygenesis was demonstrated in 978 Old World monkeys, 390 great apes, 194 lesser apes and 5,000 humans of Caucasoid and Negroid stock. The frequency of agenesis was highest in the human sample, particularly in the Negroids, that of polygenesis was highest in the great apes. Within both groups, the polymorphism was commonest in the molar (predominantly third molar) region. Despite numerous difficulties in the interpretation of such data, on the basis of the differences between man, apes and monkeys, it is suggested that the high incidence of agenesis seen in man is a phylogenetic accompaniment of the shortening of the maxillomandibular skeleton, which is such a marked feature of human evolution.  相似文献   

20.
This paper deals with the systematic position of Gen. Roegneria C. Koch by numerical taxonomic method. The genus Roegneria C. Koch and its relatively related genera (Agropyron Gaerth., Elymus L., Elytrigia Desv., Leymus Hochst.) were selected as OTUS. The numerical classification was based on 30 characters, of which 18 are morphological (gross and microscopic) and 12 cytological. The dendrogram (Fig. 1.) is the optimal one, which is selected according to the cophenetic correlation coefficient. Moreover, the results of other cluster methods, which are based on either the correlation coefficient or the distance coefficients, show the same structure similar to the Fig. 1. Hance, Gen. Roegneria is considered congeneric with Gen. Elymus. According to the priority of International Code, Gen. Roegneria C. Koch should be referred to Gen. Elymus L.  相似文献   

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