青藏高原裂腹鱼亚科鱼类的分类、系统发育和生物地理学—基于线粒体DNA细胞色素b的研究

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	青藏高原裂腹鱼亚科鱼类的分类、系统发育和生物地理学—基于线粒体DNA细胞色素b的研究
其他题名	Taxonomy, phylogeny and biogeography of Schizothoracinae in the Qinghai-Tibetan Plateau inferred from mitochondrial cytochrome b sequences
	祁得林
学位类型	博士
导师	赵新全
	2007-06-09
学位授予单位	中国科学院西北高原生物研究所
学位授予地点	西北高原生物研究所
关键词	裂腹鱼亚科裸裂尻鱼属黄河裸裂尻鱼分子系统发育分子钟生物地理学遗传多样性种群历史结构趋同进化青藏高原水系演化线粒体细胞色素b基因
摘要	裂腹鱼亚科隶属于鲤形目（Cypriniformes），鲤科（Cyprinidae），是特产于亚洲高原地区的一群鲤科鱼类，全球共有15属，约100多个种。在中国，共有10~11属，约70余种，占世界裂腹鱼有效种数的80%以上，主要分布在青藏高原及其毗邻的河流、湖泊之中，极适应于青藏高原水域的生物条件和非生物条件，是青藏高原鱼类三大类群之一。由于青藏高原特殊的地理环境，分布在高原的裂腹鱼亚科鱼类在长期的进化演变过程中逐步形成了耐高寒、抗缺氧等优良特性，曾一度受到生物学家的注目。虽然，生物学家已从传统分类学、细胞遗传学、生物化学、生态学等方面对裂腹鱼亚科鱼类进行了大量的研究，但是在该亚科鱼类系统发育关系和历史生物地理学研究方面存在较大的空白和争议。因此，本文利用线粒体细胞色素b序列构建了裂腹鱼亚科鱼类属间系统发育关系，在此基础上，选择一广布属和一广布种分别研究了广布属的系统发育关系和广布种遗传多样性以及种群历史结构，获得以下研究结论： 1. 利用本亚科鱼类18条新测定的cyt b 序列和18条已发表序列（来自GenBank），以及13条鲤科相关亚科鱼类序列，构建了最大似然树（ML）、最大简约树（MP）和贝叶斯（Bayesian）系统发育树。采用KH 和SH 对不同系统发育假设进行了检验。并应用NPRS法估算了裂腹鱼亚科鱼类的分化时间，结果表明：（1）裂腹鱼亚科鱼类是一个存在于自然界的单系群，并且与鲃亚科鱼类有着较近的亲缘关系，支持裂腹鱼亚科鱼类源自鲃亚科鱼类的观点；（2）裂腹鱼亚科鱼类分为三个大的族群，第一族群仅包括Schizothorax，第二族群包括Diptychus和Gymnodiptychus，第三族群包括Ptychobarbus、Gymnocypris、Oxygymnocypris、Schizopygopsis、Chuanchia、Platypharodon和Herzensteinia，其中，第一族群作为原始群置于发育树底部，而第三族群的Schizopygopsis处于发育树顶部，与形态特征构建的系统发育不相一致。（3）序列差异、系统发育关系和KH 和SH 检验均支持将高原鱼属（Herzensteinia）合并到裸裂尻鱼属（Schizopygopsis）的观点，同时不支持将Schizothorax下分两个亚属的观点。（4）分子钟估计显示裂腹鱼亚科鱼类起源于14.1Mya，主要族群分化时间在11.2Mya和9.5 Mya，而其主要种化事件发生于6.1~0.4 Mya，暗示青藏高原自6.1Mya以后所发生的强烈隆升事件对裂腹鱼亚科鱼类的物种分化、扩散产生了深刻的影响。 2. 裸裂尻鱼属（Schizopygopsis）是裂腹鱼亚科鱼类的一个广布属，分布于青藏高原主要水系，其栖息地涵盖1300~5200m的不同海拔梯度，是裂腹鱼亚科鱼类中研究物种进化与青藏高原隆升之间关系的模式属。本研究测定了31个个体，共10个种和亚种的cyt b 序列。通过ML、MP、NJ和Bayesian系统发育分析，结合分子钟估计和隔离-扩散（Dispersal-vicariance）分析结果表明：（1）裸裂尻鱼属鱼类是一个单系群，分成四个主要族群，第一族群包括来自西藏的G. namensis、S. younghusbandi、S. younghusbandi wui和S. younghusbandi himalayensis，第二族群只有S. anteroventris，该种仅分布在澜沧江上游干支流，第三族群由S. malacanthus和S. thermalis两个种组成，前者分布在雅砻江上游干支流水系，后者仅分布在怒江上游支流中，第四族群包括五个种和亚种，H. microcephalus、S. chengi、S. kialingensis、S. pylzovi和S. kessleri，其中S. younghusbandi处于进化树的基底部；（2）序列差异和系统发育关系支持S. kessleri是S. pylzovi的同物异名的观点，将S. chengi提升为独立种，并支持引用S. anteroventris的种名，将G. namensis纳入到该属中；（3）裸裂尻鱼属鱼类在长期的演化过程中发生了某些形态特征，如下颌角质化边缘、下咽骨形状等的趋同进化，利用这些性状进行分类学地位研究和构建系统发育关系要慎重。（4）本文所估计的裸裂尻鱼属鱼类的物种起源在2.65百万年左右，对应于青藏运动A幕晚期，而主要物种的形成时间对应于青藏运动C幕，表明裸裂尻鱼属鱼类的物种起源和分化等进化事件，可能与青藏高原自3.6百万年前开始的强烈隆升所致的高原水系变迁和生态环境的变化有着密切的关系，而青藏运动C幕后的古气候波动和水系演化可能对该属鱼类种化和扩散居有重要作用。（5）裸裂尻鱼属鱼类目前离散的分布格局可能源自祖先广泛分布域的片断化（Vicariance），即在物种分化和形成中隔离事件发挥了主导作用，而并不是通过扩散（Dispersal）来自于局限的起源中心。 3. 黄河裸裂尻鱼（S. pylzovi）广泛分布于黄河水系干支流、柴达木内流水系和高原诸多湖泊。作为一个重要的渔业资源，S. pylzovi在青藏高原淡水生态系统的食物链中具有重要的地位，但是其分布在地理上呈离散状。本研究测定了来自黄河干支流、柴达木内陆水系和封闭性湖泊的9个栖息水域133个个体的cyt b 序列。通过系统发育分析、遗传多样性、种群结构和嵌套进化支序分析（NCPA），结果表明：（1）分布于外流水系和托索湖的黄河裸裂尻鱼种群核苷酸多样显示为中等水平（0.0024~0.0045），而来自柴达木盆地的种群表现出非常低的核苷酸多样度（0.0018~0.0021），这可能与柴达木盆地古气候环境的波动有关，暗示柴达木盆地的黄河裸裂尻鱼种群可能经历过某种瓶颈效应；（2）黄河裸裂尻鱼在水系内种群间或水系间具有显著的遗传差异，反映出黄河裸裂尻鱼具有显著的种群结构。古气候环境的波动和主要水系的演化可能促进了黄河裸裂尻鱼种群的邻域扩张，但是后续水系间的地理隔离导致了黄河裸裂尻鱼分布域的片段化，从而使种群间的基因交流受阻；（3）黄河裸裂尻鱼各种群间的隔离事件相对较晚，致使在分子系统发育树中没有形成各种群相应的单系群；（4）黄河裸裂尻鱼种群Fs具有显著的负值（-24.91, P<0.01），结合单倍型歧点分布分析，说明黄河裸裂尻鱼曾经经历过突然或近期的种群扩张事件。种群大爆发事件可能发生于青藏高原共和运动后（0.11Mya）；（5）就黄河裸裂尻鱼目前种群结构和各种群间基因交流受阻的状况而言，各种群应该独立管理和保护，从而达到保存种群遗传完整性的目的。 4. 相似或相同的栖息地生态环境通常会引发物种间的表型趋同进化，分布于南门峡河流的裂腹鱼亚科鱼类是这种进化的一个典型实例。本研究测定了南门峡裂腹鱼亚科鱼类（n=29）及其近缘种（n=19）共48个个体的cyt b序列，并以厚唇裸重鱼和尖裸鲤为外群构建了MP和Bayesian 系统进化树。结果表明，南门峡裂腹鱼亚科鱼类29个个体在系统发育树上分布于两个截然不同的族群中，表明分南门峡裂腹鱼亚科鱼类可能是花斑裸鲤和黄河裸裂尻鱼形态相似种的复合体。结合青藏高原隆升所致的气候环境变化和高原北部水系变迁的事件，推断形态趋同进化可能导致了南门峡河流裂腹鱼亚科鱼类形态相似种的共存，而小生境自然选择压力是引发适应性形态趋同进化的主要原因。
其他摘要	Schizothoracine fishes, members of family Cyprinidae, are endemic to Asian highlands including 15 genera and ca. 100 species. In China, more than 70 species belonging to ca.10 extant or nominal genera account for over 80% of the world’s schizothoracine fishes. They are mainly distributed in lakes and rivers of the Qinghai-Tibetan Plateau and adjacent areas. As one of the three largest fish groups in the Qinghai-Tibetan Plateau, the schizothoracine fishes tolerate high hypoxia and low temperature and show highly adaptive to the peculiar ecological condition of the region, which give them an abvious biological interest. Despite a lot of studies have been conducted in the traditional classification, cytogenetics, biochemistry, ecology and other aspects, there are still existing gaps and controversials in phylogenetic relationships and historical biogeography within the subfamily. In this study, we used the complete cytochrome b (cyt b) gene sequences to reconstruct the phylogenetic relationships and estimate the divergence times within this subfamily. At the same time, we investigated the phylogenetic relationships of one widely distributed genus from this subfamily, and studied the genetic variation and historical population structure of one species from the widely distributed genus. The main conclusions of the present study are as follows: 1. A total of 36 cyt b sequences, including 18 sequenced in the present study and 18 obtained from the GenBank, represent 36 species of subfamily Schizothoracinae. In order to test the monophyly of this subfamily, additional 13 sequences representing 9 related subfamilies of the family Cyprinidae obtained from the GenBank were included in the present study. All sequences were subjected to maximum parsimony (MP), maximum likelihood (ML), and Bayesian analyses. Alternative phylogenetic relationships were statistically compared using the Kishino–Hasegawa (KH) and Shimodaira–Hasegawa (SH) tests. Divergence times were estimated using nonparametric rate smoothing (NPRS) method. The results show that: (1) The subfamily Schizothoracinae forms a well-supported monophyletic group having close relationship with species of subfamily Barbinae, which support the viewpoint that the Schizothoracinae is derived from the species of subfamily Barbinae. (2) The subfamily Schizothoracinae falls into three major well–supported clades: the first clade, basal to others, is formed by the genus Schizothorax; the second clade is formed by Diptychus and two species of the genus Gymnodiptychus; and the third clade is the largest group including Ptychobarbus, Oxygymnocypris, Gymncypris, Chuanchia, Platypharodon, Schizopygopsis, Herensteinia and the species Gymnodiptychus integrigymnatus. The molecular phylogenetic relationships within this subfamily are not consistent with the previous study based on the morphological characters. (3) The results of sequence divergence and phylogenetic analyses and KH and SH tests support that the monotypic genus Herzensteinia should be incorporate into the genus Schizopygopsis, while don’t support the classification to divide the genus Schizothorax into two subgenera. (4) The origin of the subfamily Schizothoracinae occurred14.1Mya, and the divergence of major clades within the subfamily Schizothoracinae happened during 11.2Mya and 9.5Mya, and the main speciation events occurred largely 6.1~0.4 Mya, suggesting that the intensive uplifts of the Qinghai-Tibetan Plateau over the past 6.1 Mya have significant impact on the speciation, divergence and radiaion of this subfamily. 2. Schizopygopsis is one widely distributed genus of subfamily Schizothoracinae and inhabits main drainages at different levels of elevation in the Qinghai-Tibetan Plateau. Schizopygopsis, therefore, is an ideal model with which to investigate the biogeographical history of the Qinghai-Tibetan Plateau because it will allow us to examine the impact of changes in plateau ecogeography on the evolution of a widespread fish group in this region. In the present study, 31 cyt b sequences representing 10 species and subspecies of Schizopygopsis were obtained and performed maximum parsimony (MP), maximum likelihood (ML), neighbor-joining (NJ) and Bayesian analyses. Phylogenetic hypotheses generated from our molecular data, coupled with dispersal–vicariance analyses indicate that: (1) The genus Schizopygopsis is a monophyletic group, and includes four major clades within it: the first clade consists of G. namensis, S. younghusbandi, S. younghusbandi wui, and S. younghusbandi himalayensis, all from drainages in Tibet; the second clade includes only S.anteroventris which inhabits the upper reach of the Lancangjiang River; the third clade includes two species, one from the Yarlunjiang River (S. malacanthus) and another from the upper reach of the Nujiang River (S. thermalis); and the fourth clade encompassed five H. microcephalus, S. kialingensis, S. chengi, S. pylzovi and S. kessleri with broad distribution. In this topology, S. younghusbandi was placed as the most basal positon. (2) The phylogenetic relationships and genetic distances suggest that S. kessleri should be recognised as a synonym of S. pylzov, S. malacanthus chengi should be elevated to specific status, keeping the species name of S. chengi, while S. anteroventris should be a distinct species in the genus Schizopygopsis. In addition, the species G. namensis should be assigned into the genus Schizopygopsi. (3) The species of genus Schizopygopsis may have experienced convergent evolution in many morphological characters such as the states of horny sheath on the lower jaw and pharyngeal bone. Therefore, careful consideration should be given in taxonomic and phylogenetic studies based on these morphological characters. (4) We tentatively date the origin of the genus Schizopygopsis during Qinghai-Tibetan Movement phase A (late Pliocene), while the main speciation events occurred largely after Qinghai-Tibetan Movement phase C (Pleistocene), suggesting that the evolutionary events linked to the origin and speciation of this genus correlated with the intensive uplifts of the Qinghai-Tibetan Plateau over the past 3.4 Mya, and fluctuations of ecogeographical environment and drainage patterns caused by tectonic events after Qinghai-Tibetan Movement phase C may play a dominant role in speciation and diversification of the genus Schizopygopsis. (5) The current observed disjunct distributions between sister groups are likely resulted from the fragmentations of a widespread ancestor of genus Schizopygopsis (vicariance), rather than dispersal from a more restricted ‘centre of origin’. 3. Schizopygopsis pylzovi, one species of genus Schizopygopsis pylzovi, is widely distributed in the upper reaches of Yellow River, inflow drainages in the Qiadam Basin and isolated lakes in the Qinghai-Tibetan Plateau. As an important nature fishery resource, it plays significant roles in the trophic web of plateau freshwater communities, but it has a discrete geographic distribution in the Qinghai-Tibetan Plateau. In the present study, complete sequences of the cytochrome b gene from 133 specimens were obtained from 9 localities to assess genetic diversity and infer population histories of the freshwater fish Schizopygopsis pylzovi. The results show that: (1) Nucleotide diversities are moderate (0.0024–0.0045) in populations from outflow drainage system and Tuosuo Lake, but low (0.0018–0.0021) in populations from Qiadam Basin. It is probable that the low intra-population variability is related with the paleoenvironmental fluctuation in Qiadam Basin, suggesting that the populations from Qiadam Basin have experienced severe bottleneck events in history. (2) A significant genetic variation is observed among populations within drainage systems and among drainage systems, indicating significant geographical structuring of Schizopygopsis pylzovi. The fluctuations of ecogeographical environment and major hydrographic formation might have promoted contiguous range expansion of freshwater fish population, whereas the geological barriers among drainages have resulted in fragmentation of population and restricted gene flow among populations. (3) Population isolations of Schizopygopsis pylzovi may be occurred too recently for the populations from different drainages to have attained reciprocal monophyly respectively. (4) The significantly large negative Fs value (-24.91, P<0.01) of Fu’s Fs test and the unimodal mismatch distribution indicate that the species Schizopygopsis pylzovi have undergone a sudden population expansion after the historical tectonic event of Gonghe Movement (0.11Mya). (5) The results of this study suggest that each population of Schizopygopsis pylzovi should be managed and conserved separately and that efforts should be directed towards preserving the genetic integrity of each group. 4. It is well kowen that same or similar ecological environment of habitats could cause convergent evolution in morphological characters among highly related species. It is the case in the evolution of the schizothoracine fishes distributed in the Nanmenxia River. In this study, the complete sequences of the cyt b gene from 29 individuals of the schizothoracine fishes in Nanmanxia River and 19 individuals representing other relatively closed species were sequenced. All sequences were subjected to maximum parsimony (MP) and Bayesian analyses. The results show that the 29 individuals form two divergent clades in the phylogentic trees, coupled with the sequence divergence analysis suggest that the schizothoracine fishes in Nanmanxia River may be morphological similar species complex consisted of two species, Gymnocypris eckloni and Schizopygopsis pylzovi. The natural selective pressure resulted from the changes of water system and climatic conditions due to uplifts of the plateau may have promoted the adaptive convergence of the morphological characters.
页数	137
语种	中文
文献类型	学位论文
条目标识符	http://210.75.249.4/handle/363003/3090
专题	中国科学院西北高原生物研究所
推荐引用方式 GB/T 7714	祁得林. 青藏高原裂腹鱼亚科鱼类的分类、系统发育和生物地理学—基于线粒体DNA细胞色素b的研究[D]. 西北高原生物研究所. 中国科学院西北高原生物研究所,2007.

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