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1.
东亚似Ju类鱼类的起源和演化   总被引:3,自引:1,他引:2  
本文采用分支扩散法和分支离散法两种生物地理学方法分析了似Ju类的起源和演化,结果说明似Ju类于第三纪末起源于中国北方的原始Ju类,逐步向南扩散,在其物种分化过程中可能存在南北两个分化中心。  相似文献   

2.
黄海伪虎鲸mtDNA 控制区序列的测定和初步分析   总被引:2,自引:1,他引:1  
张婷  杨光  周开亚  魏辅文 《兽类学报》2005,25(3):219-223
测定了黄海7 头伪虎鲸mtDNA 控制区5’端533 bp 的序列, 共发现54 个变异位点, 定义了4 种单元型。最大似然法和邻接法的系统树均把单元型聚为2 分支。两支之间没有共享单元型且无姊妹关系。分支间的核苷酸序列差异显著地超过了其它海豚类种间的序列差异水平, 提示传统意义上的伪虎鲸可能包括了具有显著遗传差别的不同物种, 迫切需要开展进一步的研究。  相似文献   

3.
岛屿生物地理学理论的核心过程是岛屿物种的周转, 包括迁入与灭绝。本研究旨在探讨扩散能力差异对岛屿繁殖鸟类群落动态的影响。2007年4月至2013年6月, 采用样线法调查了千岛湖36个陆桥岛屿的繁殖鸟类, 依据扩散能力强弱将其划分为两类, 结合陆桥岛屿参数, 并运用逻辑斯蒂回归模型和最大似然法, 来研究鸟类扩散能力的不同对其周转率的影响。结果表明, 千岛湖繁殖鸟类扩散能力强的物种具有较高周转率且受岛屿参数约束较小, 而扩散能力弱的物种周转率较低且对岛屿参数变化更敏感。因此, 千岛湖陆桥岛屿繁殖鸟类的扩散能力显著影响其群落动态。  相似文献   

4.
对似近分析的一点改进及其拓广   总被引:2,自引:1,他引:1  
本文给出了似近分析一个重要的改进,并将改进的似近分析推广为m维似近分析,同时给出了两个数学定理及其证明。根据多维似近系数的数学性质,提出了一种新的聚类方法,即逐步多维聚类法。实例分析证明,这种聚类法比二维系数聚类优越,聚类功能强,所获得的结果更为客观。  相似文献   

5.
似鮈类鱼类的系统发育研究(鲤形目:鲤科)   总被引:1,自引:0,他引:1  
本文通过对似类8属13种和外类群7属10种鱼类的比较研究,选取37个骨骼及外部特征,运用外类群比较法进行特征分析,根据分支系统学原理重建了似类的系统发育。特征分析和系统发育分析表明似类是具有许多共同离征的单系群,朝着流水性底栖生活和刮食性的主干方向发展;其中以似属最原始,胡属最特化构成7对姐妹群。蛇属是较早分化出的相对特化的类群,棒花鱼属和小鳔属的关系相对较远。  相似文献   

6.
本文通过对似Ju类8属13种和外类群7属10种鱼类的比较研究,选取37个骨骼及外部特征,运用外类群比较进行特征分析,根据分支系统学原理重建了似Ju类的系统发育。特征分析和系统发育分析表明似ju类是具有许多共同离征的单系群,朝着流水性氏栖生活和刮食性的主干方向发展;其中以似Ju属最原始的,胡Ju属最特化构成7对姐妹群,蛇Ju属是较早分化出的相对特化的类群,棒花鱼属和小鳔Ju属的关系相对较远。  相似文献   

7.
刀切法估计动物种群扩散型指数   总被引:1,自引:0,他引:1  
一、引言研究动物种群空间格局,无论在生态学理论还是应用上都具有重要意义。用扩散型指数研究种群空间格局不受格局类型的限制,能反映空间格局的连续统(Continuum).长期以来,对扩散型指数的数值估计,大多采用矩法或最大似然法,由于扩散型指数的统计分布一般都比较复杂,而非正态,因而用建立在正态分布基础上的矩估计或最大似然估  相似文献   

8.
干细胞是指能无限自我复制的原始细胞。本文综合介绍了目前有关造血干细胞和肿瘤干细胞的定量研究方法,概述了采用脾集落形成法、体外软琼脂集落形成法和扩散盒及琼脂扩散盒方法获得的常用抗肿瘤药物对两类干细胞作用的资料。  相似文献   

9.
干细胞是指能无限自我复制的原始细胞。本文综合介绍了目前有关造血干细胞和肿瘤干细胞的定量研究方法,概述了采用脾集落形成法、体外软琼脂集落形成法和扩散盒及琼脂扩散盒方法获得的常用抗肿瘤药物对两类干细胞作用的资料。  相似文献   

10.
本文利用偏泛函微分方程的相关理论分析了一类含扩散项时滞肿瘤模型的分支理论,研究了该模型平衡点的线性稳定性、余维一分支和余维分支,包括Hopf分支、B-T分支、超临界分支和稳态分支.结论表明这类模型的扩散项对相应的分支结论不会产生影响.即在具体模型中不需要考虑机体内细胞的扩散.  相似文献   

11.
The members of the cyprinid subfamily Gobioninae, commonly called gudgeons, form one of the most well-established assemblages in the family Cyprinidae. The subfamily is a species-rich group of fishes, these fishes display diverse life histories, appearances, and behavior. The phylogenetic relationships of Gobioninae are examined using sequence data from four loci: cytochrome b, cytochrome c oxidase I, opsin, and recombination activating gene 1. This investigation produced a data matrix of 4114 bp for 162 taxa that was analyzed using parsimony, maximum likelihood, and Bayesian inference methods. The phylogenies our analyses recovered corroborate recent studies on the group. The subfamily Gobioninae is monophyletic and composed of three major lineages. We find evidence for a Hemibarbus-Squalidus group, and the tribes Gobionini and Sarcocheilichthyini, with the Hemibarbus-Squalidus group sister to a clade of Gobionini-Sarcocheilichthyini. The Hemibarbus-Squalidus group includes those two genera; the tribe Sarcocheilichthyini includes Coreius, Coreoleuciscus, Gnathopogon, Gobiocypris, Ladislavia, Paracanthobrama, Pseudorasbora, Pseudopungtungia, Pungtungia, Rhinogobio, and Sarcocheilichthys; the tribe Gobionini includes Abbottina, Biwia, Gobio, Gobiobotia, Huigobio, Microphysogobio, Platysmacheilus, Pseudogobio, Romanogobio, Saurogobio, and Xenophysogobio. The monotypic Acanthogobio is placed into the synonymy of Gobio. We tentatively assign Belligobio to the Hemibarbus-Squalidus group and Mesogobio to Gobionini; Paraleucogobio and Parasqualidus remain incertae sedis. Based on the topologies presented, the evolution of swim bladder specializations, a distinctive feature among cyprinids, has occurred more than once within the subfamily.  相似文献   

12.
Sciaenid fishes are widely distributed throughout the coastal waters and estuaries of the world. A total of 23 genera of this family are endemic to the Old World. However, evolutionary relationships among Old World sciaenid fishes and their origin have remained unresolved despite their diversity and importance. Besides, hypotheses that explain the origin and biogeographical distribution of sciaenid fishes are controversial. In this study, the complete mitochondrial genome sequences of seven representative sciaenid species were determined and a well-resolved tree was recovered. This new timescale demonstrated that the sciaenid originated during the late Jurassic to early Cretaceous Period. The estimated origin time of sciaenid fish is 208 Mya, and the origin of Old World sciaenid is estimated at 126 Mya. Reconstruction of ancestral distributions indicated a plesiomorphic distribution and center of origin in the New World, with at least one lineage subsequently dispersed to the Old World. Moreover, we conclude that the common ancestors of Old World sciaenid fishes were derived from species of New World.  相似文献   

13.
粉条儿菜属(AletrisL.)隶属于肺筋草科,全世界有23种1变种,东亚有18种1变种,北美东南部有5种,为典型的东亚-北美间断分布的属.本文在种(变种)的水平上,研究了粉条儿菜属的地理分布及其分布中心和多样化中心,并对其起源和分化以及现代洲际间断分布格局的成因进行了分析.结果表明,(1)中国共分布有粉条儿菜属植物15种1变种,而广义的横断山地区集中分布有13种1变种,是东亚粉条儿菜属植物分布最为集中的地区,而且包含该属植物各个进化阶段的代表.因此,广义的横断山地区是粉条儿菜属在东亚的分布中心和多样化中心.(2)根据粉条儿菜属及其近缘属的分布格局推测,该属可能在不晚于第三纪早期,起源于古北大陆.东亚和北美的粉条儿菜属植物形态区别明显,应该是隔离分化的结果.(3)该属植物可能曾经广布于北半球,后来地质、气候以及冰川等因素的变化,导致该属在一些地区灭绝,而仅存于东亚和北美东南部.(4)尽管横断山及其周边地区是东亚粉条儿菜属的多样化中心,但该地区很可能并不是粉条儿菜属最早的分化中心,因横断山地区周边的一些特有种可能是在晚近的时期形成的新特有种;另外,东亚粉条儿菜属一些原始的种类主要分布于我国中东部到日本一带.所以,中国中东部到日本一带可能是粉条儿菜属早期的分化中心.  相似文献   

14.
Global biodiversity peaks in the tropical forests of the Andes, a striking geological feature that has likely been instrumental in generating biodiversity by providing opportunities for both vicariant and ecological speciation. However, the role of these mountains in the diversification of insects, which dominate biodiversity, has been poorly explored using phylogenetic methods. Here we study the role of the Andes in the evolution of a diverse Neotropical insect group, the clearwing butterflies. We used dated species-level phylogenies to investigate the time course of speciation and to infer ancestral elevation ranges for two diverse genera. We show that both genera likely originated at middle elevations in the Andes in the Middle Miocene, contrasting with most published results in vertebrates that point to a lowland origin. Although we detected a signature of vicariance caused by the uplift of the Andes at the Miocene–Pliocene boundary, most sister species were parapatric without any obvious vicariant barrier. Combined with an overall decelerating speciation rate, these results suggest an important role for ecological speciation and adaptive radiation, rather than simple vicariance.  相似文献   

15.
洞穴鱼类:概念、多样性及研究进展   总被引:7,自引:0,他引:7  
洞穴鱼类是淡水鱼类中一个特殊的生态类群,其生活史的自然完成离不开洞穴或地下水环境。洞穴鱼类可分为典型和非典型两种类型,前者具有易辨识的特殊适应性形态结构(如眼消失、身体透明等),后者此类特征不明显。目前世界典型洞穴鱼类共记录有107种,其中鲤形目和鲇形目的种类最多,分别占49.5%和24.3%;在科级水平上以鲤科和爬鳅科最为丰富。东南亚和中南美是洞穴鱼类多样性最高的地区,有着世界上75.0%的典型洞穴鱼类。中国的洞穴鱼类具有物种多样性高、但集中出现在个别类群(如金线鲃属(Sinocyclocheilus)和高原鳅属(Triplophysa))、物种分化强烈、分布范围狭窄、种群数量小等特点。洞穴鱼类学是一门交叉科学,研究涉及系统学、生态学、生理学、保护生物学等众多学科领域,但目前研究仍多围绕演化问题展开。中国洞穴鱼类研究还处于系统分类和区系研究水平,其他有关学科的研究有待开展。  相似文献   

16.
绣线菊亚科是蔷薇科最原始的亚科,共有22属260余种, 包括常绿和落叶两大类群,前者是 原始类型。我国有8属100种,全都为落叶性。本文着重讨论中国各属的起源、演化和分布等 ,同时也概述全亚科植物在世界各植物区的分布等问题。绣线菊属Spiraea是该亚科落叶类群中最原始的属,它在早期发生趋异进化,衍生出形态各异而亲缘关系密切 的不同属,本文阐明了中国各属的系统位置和属间的亲缘关系。通过对我国各属地理分布的 分析对比,属的分布区可归纳为5个类型。对全球绣线菊亚科植物在世界各植物区中的属、种数统计表明,东亚区有8属105种,其中有96个特有种,是该亚科植物分布最多而又最集中 地区,具有在系统发育上处于各主要演化阶段的落叶类型,因此,东亚区是全球绣线菊亚科植 物的现代分布和分化中心,也是落叶类群发生和发展的关键地区。在北美洲,从马德雷区至落基山区一带分布着11属46种,均为特有种,显然北美洲西部也是该亚科植物的现代分布中心,但可能是第二分布中心。南美洲至今保存2个较古老的常绿属,即Quillaja和K ageneckia,基于此,南美洲可能是绣线菊亚科某些常绿属早期分化和发展的关键地区 。中国绣线菊亚科植物在东亚区占绝对优势,有8属82种,其中有62个特有种,分别占该区属 、种和 特有种数的100%、82%、和65%, 这些类群分布最密集地区是在中国喜马拉雅森林植物亚区 中的横断山脉地区和中国日本森林植物亚区的西部,这一带是中国绣线菊亚科的现代分布和多样性中心,很可能是某些属的发源地。由此看来,绣线菊亚科的落叶属可能起源于劳亚古陆。据化石记载,该亚科植物的起源时间可以追溯到白垩纪早白垩世。  相似文献   

17.
The subfam. Spiraeoideae, consisting of 22 genera and more than 260 species in the world,is the most primitive subfamily of Rosaceae. It has developed into two groups,i.e. evergreen and deciduous ones, of which eight genera and 100 species in China are totally deciduous. In the present paper, the origin,evolution and distribution of the Chinese genera is discussed mainly, and the distribution of the whole subfamily in the floristic regions of the world is also mentioned. Based on evolutionary trends of morphological characters, Spiraea L. is considered as the most primitive genus in the deciduous group of subfam. Spiraeoideae, from which some genera are been derived, the systematic position and evolutionary relationships between different genera are elucidated in this paper. Through the analysis on the geographical distribution of the genera in China, the areal types may be divided as follows: (1) North Temperate Type: Spiraea, Physocarpus, Aruncus. (2) East Asian and North American Disjunct Type: Sorbaria. (3) Mediterranean, West Asian (or Central Asia) and East Asian Type: Sibiraea. (4) Temperate Asian Type: Exochorda.(5) East Asian Type: (a) Sino Himalayan Distribution: Neillia; (b) Sino Japan Distribution: Stephanandra. After analysis of the distribution of subfam. Spiraeoideae in the world, it is shown that the Eastern Asiatic Region, being the richest in genera, species and endemic species of the world,is not only the center of distribution and differentiation,but also an important region for occurrence and development of some deciduous genera of this subfamily, while in North America, the Madrean Region and Rocky Mountain Region, genera, species and endemic species are abundant, which indicates that the western part of North America is also the distribution center of this subfamily at the present, but it may be the secondary center of distribution. It can be seen that the relatively primitive and evergreen g enera, i.e. Quillaja and Kageneckia, are now confined to South America. The fact implies that the South America may be the region for early differentiation and development of the evergreen genera in Subfam. Spiraeoideae. The analysis of Chinese plants has shown that China has the most members of the subfamily in Eastern Asiatic Region, with eight genera, 82 species and 62 endemic species and that the maximum concentration is in western Sichuan, northwestern Yunnan and their adjacent areas. It is very obvious that the center of distribution and diversity of Subfam. Spiraeoideae in China lies in the Hengduan Mountain Region of Sino Himalayan Forest Subkingdom and the western part of Sino Japan Forest Subkingdom, where may be the birthplace of some genera in China. It may be considered that the deciduous genera of Subfam. Spiraeoideae might have originated in Laurasia.According to the fossil records, the time of origin of Subfam.Spiraeoideae dates back to the Lower Cretaceous.  相似文献   

18.
云南森林植物区系研究   总被引:3,自引:1,他引:2  
李文政  裴盛基   《广西植物》1991,11(4):293-303
云南森林植物(系指木本植物)主要起源于新生代,少数古老种起源于古生代至中生代。云南森林植物区系成分极为丰富而复杂,据研究已知森林植物149科(蕨类植物1科,裸子植物10科,被子植物138科),840属,5271种。本文根据对云南森林植物15个分布区类型统计分析,证明云南森林植物区系明显富于热带性同时兼有丰富的温带成分,热带属占总属数72.12%,温带属占总属数21.87%,中国特有属在云南有46属,占云南总属数5.33%。中国特有属的三个分布中心。有两个分布中心在云南(即新特有属中心和古老特有属中心)。本文还对云南森林植物区系的地理成分起源;云南森林植物区系成分复杂、丰富之成因;云南森林植物开发利用之前景进行了研究和探讨。  相似文献   

19.
赣东北地区鱼类区系特征及我国东部地区动物地理区划   总被引:4,自引:3,他引:1  
本文依据赣东北鱼类区系的特征,结合古地史资料,从历史时空的角度分析其区系的形成和演化;进而对我国东部地区淡水鱼类动物地理区划进行了讨论并指出:赣东北以及整个长江中下游地区应隶属于东洋区;南岭──武夷山──天台山──仙霞岭可构成东洋区南东亚亚区内次一级地理区划的分界线,即华东小区和华南小区的分界线;洞庭湖水系、鄱阳湖水系和钱塘江水系应享有相同的区划级别,同处于东洋区南东亚亚区华东小区内。  相似文献   

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