945 resultados para Primates, Origin, Phylogeny
Resumo:
把1870-2001年来自美国"现代灵长类文献题录数据库"、"维普中文数据库"及"中国灵长类研究文献题录"的资料按4个时期(I:1870-1949;Ⅱ:1950-1965;Ⅲ:1966-1977;Ⅳ:1978-2001)分类整理.此外,使用了"科学引文数据库(扩展版)".结果如下:(1)1870-2001年共有20 52篇文献,2个文献数量高峰分别出现于1950-1965和1978-2001年;科研部门所发表的论文占54.2%,并随时间而增加;而国外部门则随之减少.(2)2 052篇文献中,超过9%的文献为SCI所收录,其中1966-1977年被SCI收录的文献百分比最高;在全部被SCI收录的文献中又以科研部门的占优势(59.1%);但国外部门则以其30.1%的文献被SCI收录而领先.(3)统计了灵长类研究9个领域文献百分比及其变化,其中1978-2001间生态学和行为、神经生物学、繁殖和饲养快速发展;化石灵长类、形态学和解剖学减少;分类及分布、细胞及分子进化显得不甚突出;在第Ⅱ时期和第Ⅳ时期疾病防治研究相当多;保护生物学得到越来越多的关注.第Ⅳ时期作者数量最多,但每个作者的文献平均数却不如第Ⅰ时期.一般地说,在SCI收录的作者中以中国作者居多,但在第I时期唯一被SCI收录的作者则是一名外国学者;在第Ⅲ时期外国作者占被收录作者数的60%.
Resumo:
水蛇亚科属于游蛇科,包含10个属。其中7个属为单型属。选取水蛇亚科14个形态学特征进行支序分析,并利用计算机软件Hennig86对水蛇亚科中8个属之间的系统发育关系进行初步探讨,结果显示水蛇亚科分为两支Gerarda和Fordonia两个属构成姊妹群,Cerberus、Erpeton和Homalopsis三个属也构成单系群,与Vorisetal(2002)的分子系统树相同,但Cantoria属的地位则与Vorisetal(2002)的明显不同。
Resumo:
为了研究猕猴属的颅骨差异性, 从而探 讨种间在形态、功能和系统分化方面的相互联系, 测定了11 个猕猴种类的77 个颅骨变量, 用于主成 分分析和判别分析。应用巢式分析方法, 分析过程 包括3 个步骤。所有变量根据功能和部位的不同首 先分为7 个单位: 下颌、下颌齿、上颌齿、上面 颅、下面颅、面颅后部和颅腔。第2 步根据它们所 揭示的相似性(具有相同的种间及种内差异性类 型) 合并为3 个解剖区域: 咀嚼器官(下颌、下颌 齿、上颌齿) , 面颅(上面颅和下面颅) 和整个面 颅后(面颅后和颅腔) 。第3 步从3 个解剖区域筛 选出27 个变量代表整个颅骨的形态结构。除了寻 找不同的功能单位, 解剖区域及总的颅骨具有不同 的种间和种内差异类型外, 此过程对筛出研究意义 不大的变量起很重要的作用。上述分析过程分别用 于对雌、雄性和两性的研究。所研究的11 个猕猴 种类间形成了3 聚类。第1 类包括食蟹猴(Macaca f ascicularis) 、戴帽猴( M1 sinica) 和头巾猴( M1 radiata) ; 第2 类包括猕猴( M1 mulatta ) 、熊猴 (M1 assensis ) 、平顶猴( M1 nemestrina ) 和黑猿 (M1 nigra) ; 第3 类包括蛮猴( M1 sylvanus ) 、日 本猴( M1 f uscata) 、短尾猴( M1 arctoides ) 和藏 酋猴(M1 thibetana) 。分别从两性差异、食物、生态、分类和系统分化方面进行了差异性讨论, 结果 认为猕猴种间颅骨的差异性主要是由于系统分化不 同而引起个体差异所致, 即种间和种内存在的个体 差异。在主成分分析中, 这些差异在不同的区域表 现在不同的成分上。在咀嚼器官上种间的差异在第 1 主成分上, 种内的差异则在第2 主成分上。面颅 的情况则刚好相反。这两种差异在面颅后及颅腔上 则被第1 和第2 主成分所平分。这样, 种间的差异 在咀嚼器官上大于种内的差异。种内的差异在面颅 上则大于种间的差异。这两种差异在面颅后和颅腔 上则几乎大小相等。这一研究结果表明, 与传统的 概念不同, 第2 主成分不仅仅表现形态、形状的差 异, 而如同第1 主成分一样, 也表现形态的大小成 分。此研究所揭示的猕猴种间关系部分与Foden (1976 , 1980) 和Delson (1980) 相同。如平顶猴 与黑猿、短尾猴、藏酋猴和熊猴的关系。食蟹猴、 头巾猴和戴帽猴的关系则不同, 并已得到有关分子 生物学的支持, 此3 种可能来自同一祖先并经历相 同的扩散过程。此研究所设计的巢式分析过程提供 了一种很好的差异性研究手段。最终结果暗示在形 态学研究中仅仅考虑某一区域的形态结构是很不够 的, 因为不同的部分具有不同的种间及种内差异类 型。这在化石研究中尤其要注意。
Resumo:
Mitochondrial DNA (mtDNA) of six breeds of native domestic pigs from Yunnan province, southwest China, and two wild boars obtained from Sichuan, China, and Vietnam was analyzed using 20 restriction endonucleases that recognize six nucleotides. Restriction maps were made by double-digestion methods and polymorphic sites were located on the map. According to their mtDNA restriction types, all the breeds were classified into six groups. Genetic distances among groups were calculated to define their phylogenetic relationships. The relationship between the Sichuan wild boar and domestic pigs is close, while the Vietnamese wild boar is relatively far from them, so the domestic pigs in southwest China are likely to have originated from a wild pig which distributed in west China. We compare our results with previous reports in literature and discuss the relationship among Chinese pigs, Japanese pigs, and European pigs. The mtDNA cleavage pattern of the Mingguang pig digested by EcoRV was identical to that of Duroc; mutations at the EcoRI site, detected in the mtDNA of two Dahe pigs, are the same as in the Vietnamese wild boar, suggesting that mutational hot spots exist in the mtDNA of pigs.
Resumo:
Phylogenetic relationships of six species of Ochotona were investigated using mitochondrial DNA (mtDNA) restriction-site analysis. The phylogenetic tree constructed using PAUP was based on 62 phylogenetically informative sites with O. erythrotis designated as an outgroup. Two clades were evident. One contained O. curzoniae, O. huangensis, and O. thibetana. in the second, O. daurica was a sister taxon of O. cansus. The five species appear to come from different maternal lineages. The branching structure of the tree and sequence divergence confirm that huangensis and cansus are distinct species, and that mol-osa is a synonym of O. cansus rather than O. thibetana. Divergence time, estimated from genetic distances, indicates that the ancestors of the two maternal lineages diverged ca. 6.5 x 10(6) years ago. O. curzoniae diverged from O. huangensis, and O. daurica diverged from O. cansus, at about the same time (ca. 3.4 x 10(6) years ago). These data suggest a period of rapid radiation of the genus Ochotona in China, perhaps during the late Pliocene. These calculations correspond roughly to tectonic events and environmental changes in China throughout this period, and appear to be substantiated by the fossil record.
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We investigated the relationships of Asian bufonids using partial sequences of mitochondrial DNA genes. Twenty-six samples representing 14 species of Bufo from China and Vietnam and 2 species of Torrentophryne from China were examined. Three samples of Bufo viridis from Armenia and Georgia were also sequenced to make a comparison to its sibling tetraploid species B. danatensis. Bufo americanus, from Canada, was used as the outgroup. Sequences from the 12S ribosomal RNA, 16S ribosomal RNA, cytochrome b, and the control region were analyzed using parsimony. East Asian bufonids were grouped into two major clades. One clade included B. andrewsi, B. bankorensis, B. gargarizans, B. tibetanus, B. tuberculatus, its sister clade B. cryptotympanicus, and the 2 species of Torrentophryne. The second clade consisted of B. galeatus, B. himalayanus, B. melanostictus, and a new species from Vietnam. The placement of three taxa (B. raddei B. viridis, and its sister species, B. danatensis) was problematic. The genus Torrentophryne should be synonymized with Bufo to remove paraphyly. Because B. raddei does not belong to the clade that includes B. viridis and B. danatensis, it was removed from the viridis species group. The species status of B bankorensis from Taiwan is evaluated. (C) 2000 Academic Press.
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Molecular phylogeny of three genera containing nine species and subspecies of the specialized schizothoracine fishes are investigated based on the complete nucleotide sequence of mitochondrial cytochrome b gene. Meantime relationships between the main cladogenetic events of the specialized schizothoracine fishes and the stepwise uplift of the Qinghai-Tibetan Plateau are also conducted using the molecular clock, which is calibrated by geological isolated events between the upper reaches of the Yellow River and the Qinghai Lake. Results indicated that the specialized schizothoracine fishes are not a monophyly. Five species and subspecies of Ptychobarbus form a monophyly. But three species of Gymnodiptychus do not form a monophyly. Gd. integrigymnatus is a sister taxon of the highly specialized schizothoracine fishes while Gd. pachycheilus has a close relation with Gd. dybowskii, and both of them are as a sister group of Diptychus maculatus. The specialized schizothoracines fishes might have originated during the Miocene (about 10 MaBP), and then the divergence of three genera happened during late Miocene (about 8 MaBP). Their main specialization occurred during the late Pliocene and Pleistocene (3.54-0.42 MaBP). The main cladogenetic events of the specialized schizothoracine fishes are mostly correlated with the geological tectonic events and intensive climate shift happened at 8, 3.6, 2.5 and 1.7 MaBP of the late Cenozoic. Molecular clock data do not support the hypothesis that the Qinghai-Tibetan Plateau uplifted to near present or even higher elevations during the Oligocene or Miocene, and neither in agreement with the view that the plateau uplifting reached only to an altitude of 2000 in during the late Pliocene (about 2.6 MaBP).
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To investigate the genetic diversity between the populations of woolly flying squirrels (Eupetaurus) from the eastern and western extremes of the Himalayas, partial mitochondrial cytochrome b gene sequences (390-810bp) that were determined from the museum specimens were analyzed using maximum parsimony (MP) and maximum likelihood (ML) methods. The molecular data reveal that the two specimens that were collected in northwestern Yunnan (China) are members of the genus Eupetaurus. Reconstructed phylogenetic relationships show that the populations of Eupetaurus in the eastern and western extremes of the Himalayas are two distinct species with significant genetic differences (12%) and diverged about 10.8 million years ago. Eupetaurus is significantly different from Petaurista and Pteromys. The level of estimated pairwise-sequence divergence observed between Eupetaurus and Petaurista or Pteromys is greater than that observed between Eupetaurus and Trogopterus, Belomys, Glaucomys, or Hylopetes. Considering the divergence time of the two Eupetaurus groups, the glaciations and the uplift of the Himalayas and Qinghai-Tibet plateau during the Pliocene-Pleistocene period might be the major factors affecting the present distribution of Eupetaurus along the Himalayas. (C) 2004 Elsevier Inc. All rights reserved.
Resumo:
Molecular epidemiological investigation was conducted among injecting drug users (IDUs) (n = 11) and heterosexuals (n = 15) in Kunming, Yunnan Province of China. HIV-1 genotypes were determined based on the nucleotide sequences of 2.6-kb gag-RT region. The distribution of genotypes among IDUs was as follows: CRF07_BC (5/11) and CRF08_BC (5/11); subtype B' (1/11). Similarly, a majority of Kunming heterosexuals (14/15) were infected with CRF07_BC (4/15), CRF08_BC (6/15), or subtype B' (4/15), known to predominate among IDUs in China. This contrasts with trends in the coastal regions of China and surrounding southeastern Asian countries, where CRF01_AE predominates among heterosexuals. The heterosexual HIV-1 epidemic in Kunming thus appears to derive from the local IDU epidemic. Of note, subtype B' was the most prevalent strain among heterosexuals before 1997, while CRF07_BC and CRF08_BC became predominant in 2002, indicating a transition of HIV-1 genotype distribution between the early and the more recent samples from Kunming heterosexuals.
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We present an in-depth study of the myriad atomically resolved patterns observed on graphite using the scanning tunnelling microscope (STM) over the past three decades. Through the use of highly resolved atomic resolution images, we demonstrate how the interactions between the different graphene layers comprising graphite affect the local surface atomic charge density and its resulting symmetry orientation, with particular emphasis on interactions that are thermodynamically unstable. Moreover, the interlayer graphene coupling is controlled experimentally by varying the tip-surface interaction, leading to associated changes in the atomic patterns. The images are corroborated by first-principles calculations, further validating our claim that surface graphene displacement, coming both from lateral and vertical displacement of the top graphene layer, forms the basis of the rich variety of atomic patterns observed in STM experiments on graphite.
Resumo:
In situ tests in deep waterWest African clays show crust-like shear strengths within the top few metres of sediment. Typical strength profiles show su rising from mud-line to 10 kPa to 15 kPa before dropping back to normally consolidated strengths of 3 kPa to 4 kPa by 1.5m to 2m depth. A Cam-shear device is used to better understand the mechanical behaviour of undisturbed crust samples under pipelines. Extremely variable peak and residual shear strengths are observed for a range of pipeline consolidation stresses and test shear rates, with residual strengths approximating zero. ESEM of undisturbed samples and wet-sieved samples from various core depths show the presence of numerous randomly-located groups of invertebrate faecal pellets. It is therefore proposed that the cause of strength variability during shear testing and, indeed, of the crust's origin, is the presence of random groups of faecal pellets within the sediment. © 2011 Taylor & Francis Group, London.