Cyprinid phylogeny based on Bayesian and maximum likelihood analyses of partitioned data: implications for Cyprinidae systematics

Cyprinidae is the biggest family of freshwater fish, but the phylogenetic relationships among its higher-level taxa are not yet fully resolved. In this study, we used the nuclear recombination activating gene 2 and the mitochondrial 16S ribosomal RNA and cytochrome b genes to reconstruct cyprinid phylogeny. Our aims were to (i) demonstrate the effects of partitioned phylogenetic analyses on phylogeny reconstruction of cyprinid fishes; (ii) provide new insights into the phylogeny of cyprinids. Our study indicated that unpartitioned strategy was optimal for our analyses; partitioned analyses did not provide better-resolved or -supported estimates of cyprinid phylogeny. Bayesian analyses support the following relationships among the major monophyletic groups within Cyprinidae: (Cyprininae, Labeoninae), ((Acheilognathinae, ((Leuciscinae, Tincinae), Gobioninae)), Xenocyprininae). The placement of Danioninae was poorly resolved. Estimates of divergence dates within the family showed that radiation of the major cyprinid groups occurred during the Late Oligocene through the Late Miocene. Our phylogenetic analyses improved our understanding of the evolutionary history of this important fish family.     

Molecular phylogenetic relationships of Eastern Asian Cyprinidae (Pisces: Cypriniformes) inferred from cytochrome b sequences

Cyprinidae, the largest fish family, comprises ap-proximately 210 recognized genera and 2010 species that are distributed widely in Eurasia, East Indian Is-land, Africa, and North America[1]. Species richness of this family is the greatest in East Asia, for example, China has 122 genera and more than 600 species. It is difficult to build a comprehensive phylogeny of Cy-prinidae due to the large number of genera and species. The classification of this family has been subject to revisions an…     

Phylogenetic relationships of Cyprinidae (Teleostei: Cypriniformes) inferred from the partial <Emphasis Type="Italic">S6K1</Emphasis> gene sequences and implication of indel sites in intron 1

The family Cyprinidae is widely distributed in East Asia, and has the important phylogenetic significance in the fish evolution. In this study, the 5′ end partial sequences (containing exon 1, exon 2 and indel 1) of S6K1 gene were obtained from 30 representative species in Cyprinidae and outgroup using PCR amplification and sequencing. The phylogenetic relationships of Cyprinidae were reconstructed with neighbor joining (NJ), maximum parsimony (MP), maximum likelihood (ML), and Bayesian methods. Myxocyprinus asiaticus (Catostomidae) was assigned to the outgroup taxon. Similar phylogenetic relationships within the family Cyprinidae were achieved with the four analyses. Leuciscini and Barbini were monophyletic lineages respectively with the high nodal supports. Leuciscini comprises Hypophthalmichthyinae, Xenocyprinae, Cultrinae, Gobioninae, Acheilognathinae and East Asian species of Leuciscinae and Danioninae. Monophyly of East Asian clade was supported with high nodal support. Barbini comprises Schizothoracinae, Barbinae, Cyprininae and Labeoninae. The monophyletic lineage consisting of Danio rerio, D. myersi, and Rasbora trilineata was basal in the tree. In addition, the large fragment indels in intron 1 were analyzed to improve the understanding of Cyprinidae relationships. The results showed that the large fragment indels were correlated with the relations among species. Some conserved regions in intron 1 were thought to be involved in the functional regulation. However, no correlation was found between sequence variations and species characteristic size.     

Molecular phylogenetic relationships of Eastern Asian Cyprinidae (Pisces: Cypriniformes) inferred from cytochrome <Emphasis Type="Italic">b</Emphasis> sequences

Complete mitochondrial cytochrome b sequences of 54 species, including 18 newly sequenced, were analyzed to infer the phylogenetic relationships within the family Cyprinidae in East Asia. Phylogenetic trees were generated using various tree-building methods, including Neighbor-joining (NJ), Maximum Parsimony (MP) and Maximum Likelihood (ML) methods, with Myxocyprinus asiaticus (family Catostomidae) as the designated outgroup. The results from NJ and ML methods were mostly similar, supporting some existing subfamilies within Cyprinidae as monophyletic, such as Cultrinae, Xenocyprinae and Gobioninae (including Gobiobotinae). However, genera within the subfamily “Danioninae” did not form a monophyletic group. The subfamily Leuciscinae was divided into two unrelated groups: the “Leuciscinae” in East Asia forming as a monophyletic group together with Cultrinae and Xenocyprinae, while the Leuciscinae in Europe, Siberia, and North America as another monophyletic group. The monophyly of subfamily Cyprininae sensu Howes was supported by NJ and ML trees and is basal in the tree. The position of Acheilognathinae, a widely accepted monophyletic group represented by Rhodeus sericeus, was not resolved.     

Phylogenetic relationships of Cyprinidae (Teleostei: Cypriniformes) inferred from the partial S6K1 gene sequences and implication of indel sites in intron 1

The family Cyprinidae is widely distributed in East Asia, and has the important phylogenetic signifi- cance in the fish evolution. In this study, the 5′ end partial sequences (containing exon 1, exon 2 and indel 1) of S6K1 gene were obtained from 30 representative species in Cyprinidae and outgroup using PCR amplification and sequencing. The phylogenetic relationships of Cyprinidae were reconstructed with neighbor joining (NJ), maximum parsimony (MP), maximum likelihood (ML), and Bayesian meth- ods. Myxocyprinus asiaticus (Catostomidae) was assigned to the outgroup taxon. Similar phylogenetic relationships within the family Cyprinidae were achieved with the four analyses. Leuciscini and Barbini were monophyletic lineages respectively with the high nodal supports. Leuciscini comprises Hy- pophthalmichthyinae, Xenocyprinae, Cultrinae, Gobioninae, Acheilognathinae and East Asian species of Leuciscinae and Danioninae. Monophyly of East Asian clade was supported with high nodal support. Barbini comprises Schizothoracinae, Barbinae, Cyprininae and Labeoninae. The monophyletic lineage consisting of Danio rerio, D. myersi, and Rasbora trilineata was basal in the tree. In addition, the large fragment indels in intron 1 were analyzed to improve the understanding of Cyprinidae relationships. The results showed that the large fragment indels were correlated with the relations among species. Some conserved regions in intron 1 were thought to be involved in the functional regulation. However, no correlation was found between sequence variations and species characteristic size.     

Phylogeny and biogeography of the family Cyprinidae in the Middle East inferred from cytochrome b DNA- evolutionary significance of this region.

The phylogenetic relationships of cyprinid species from the Middle East and neighboring biogeographical areas were investigated using cytochrome b sequence variation in order to test hypotheses that consider the Middle Eastern area as an important interchange area or a center of speciation for the freshwater fauna. A total of 62 cyprinid species were analyzed over the complete cytochrome b fragment (1140 bp); 28 belong to the Leuciscinae subfamily and 34 to the Cyprininae. All the Leuciscinae lineage fish recorded in the Middle East are also found in Europe, which was interpreted as an important Palearctic influence in the Middle Eastern ichthyofauna consistent with the Lago Mare dispersion. However, it has also been suggested that several Danube species have their origins in the Middle East. In contrast, the Cyprininae subfamily showed three highly divergent lineages, one shared with the Euro-Mediterranean area (Barbus/Luciobarbus genus) relict of the Lago Mare dispersion, one shared with Africa (Carasobarbus/Varicorhinus subgenus), and the third shared with Asia (Garra genus). Furthermore, clades observed in the phylogenetic reconstructions are not consistent with morphometric or karyological data and disagree with previous taxonomic assumptions. Lastly, the dispersion history in the Middle East of this subfamily appears much more complicated and ancient than that of the Leuciscinae. However, taking into account Cyprininae and Leuciscinae distribution, the Middle East appears more like an important interchange area for the freshwater ichtyofauna than a center of speciation.     

Molecular phylogenetics of the family Cyprinidae (Actinopterygii: Cypriniformes) as evidenced by sequence variation in the first intron of S7 ribosomal protein-coding gene: further evidence from a nuclear gene of the systematic chaos in the family

The family Cyprinidae is the largest freshwater fish group in the world, including over 200 genera and 2100 species. The phylogenetic relationships of major clades within this family are simply poorly understood, largely because of the overwhelming diversity of the group; however, several investigators have advanced different hypotheses of relationships that pre- and post-date the use of shared-derived characters as advocated through phylogenetic systematics. As expected, most previous investigations used morphological characters. Recently, mitochondrial DNA (mtDNA) sequences and combined morphological and mtDNA investigations have been used to explore and advance our understanding of species relationships and test monophyletic groupings. Limitations of these studies include limited taxon sampling and a strict reliance upon maternally inherited mtDNA variation. The present study is the first endeavor to recover the phylogenetic relationships of the 12 previously recognized monophyletic subfamilies within the Cyprinidae using newly sequenced nuclear DNA (nDNA) for over 50 species representing members of the different previously hypothesized subfamily and family groupings within the Cyprinidae and from other cypriniform families as outgroup taxa. Hypothesized phylogenetic relationships are constructed using maximum parsimony and Basyesian analyses of 1042 sites, of which 971 sites were variable and 790 were phylogenetically informative. Using other appropriate cypriniform taxa of the families Catostomidae (Myxocyprinus asiaticus), Gyrinocheilidae (Gyrinocheilus aymonieri), and Balitoridae (Nemacheilus sp. and Beaufortia kweichowensis) as outgroups, the Cyprinidae is resolved as a monophyletic group. Within the family the genera Raiamas, Barilius, Danio, and Rasbora, representing many of the tropical cyprinids, represent basal members of the family. All other species can be classified into variably supported and resolved monophyletic lineages, depending upon analysis, that are consistent with or correspond to Barbini and Leuciscini. The Barbini includes taxa traditionally aligned with the subfamily Cyprininae sensu previous morphological revisionary studies by Howes (Barbinae, Labeoninae, Cyprininae and Schizothoracinae). The Leuciscini includes six other subfamilies that are mainly divided into three separate lineages. The relationships among genera and subfamilies are discussed as well as the possible origins of major lineages.     

Evolution and trans-species polymorphism of MHC class IIbeta genes in cyprinid fish

The polymorphism of DAB genes encoding MHC IIbeta was investigated in 11 cyprinid species from central Europe. The species belonged to four subfamilies: Cyprininae, Tincinae, Gobioninae and Leuciscinae. Two paralogous groups of sequences, DAB1 and DAB3, were recognised according to the similarity of their nucleotide and amino-acid sequences and from phylogenetic analyses using either partial exon 2 or partial exon 3 sequences. A high allelic variability among species was found for exon 2, indicating extensive MHC polymorphism. Time divergence estimation supports the separation of DAB1 and DAB3 groups predating the separation into fish subfamilies, and a cyprinid origin of the DAB genes. Phylogenetic trees using exon 2 support the hypothesis of trans-species polymorphism, which appears to be limited to the subfamily level, i.e. the presence of sequences from different species in the same allelic group was more often recognised within subfamilies Cyprininae and Leuciscinae than between them. Phylogenetic trees using exon 3 reflect the phylogenetic patterns previously found for Cyprinidae systematics. Specific nucleotides and amino-acids in exon 3 that separate both subfamilies, as well as the species within the Cyprininae subfamily were observed. A lack of segregation in leuciscin species was recognised and the alleles of different leuciscin species tend to share similar motifs in exon 3. This could be explained by the ancient and complicated dispersion history of Cyprininae and the radiation of Leuciscinae. The effects of selective pressures were investigated: (1) within species, (2) among lineages, and (3) among sites. From intraspecific analyses, exon 2 sequences were identified as the targets of diversifying selection, whilst the evolution of exon 3 seems to be under the influence of purifying selection. The analyses among lineages indicate positive selection in many branches when using exon 2, therefore confirming trans-species polymorphism, whilst the DAB lineages of exon 3 are potentially submitted to purifying selection to some extent. Moreover, our results suggest the secondary acquisition of function of DAB1 group after duplication. The analyses among sites reveal that exon 2 exhibits sites under positive selection mostly corresponding to the putative PBR sites involved in the alpha-helix structure of the protein.     

Phylogenetic significance of the kinethmoid‐associated Y‐shaped ligament and long intercostal ligaments in the Cypriniformes (Actinopterygii: Ostariophysi)

Liao, T.Y. & Kullander, S.O. (2012). Phylogenetic significance of the kinethmoid‐associated Y‐shaped ligament and long intercostal ligaments in the Cypriniformes (Actinopterygii: Ostariophysi). —Zoologica Scripta, 42, 71–87. The phylogenetic significance of the Y‐shaped and long intercostal ligaments in the Cypriniformes is examined using character optimization in 184 species representing 20 non‐ostariophysan teleost species, five ostariophysan orders, seven cypriniform families and 14 cyprinid subfamilies. Character states were optimized on the phylogenetic trees of previous studies. Given the topology of Saitoh et al. (2011) , the Y‐shaped ligament, connecting the kinethmoid to the ethmoid complex, is shown to be a synapomorphy for the Cyprinidae, with reversals observed in the Cyprininae, Danioninae, Gobioninae and Psilorhynchinae. The condition of the Y‐shaped ligament is consistent within most subfamilies with a few exceptions. Despite the exceptions, the Y‐shaped ligament may be considered as a diagnostic character distinguishing cyprinid subfamilies with otherwise similar morphology, that is, the Danioninae and Opsariichthyinae. The long intercostal ligament, connecting five to eight ribs and ascending from the subdistal end of the fifth rib, is present in the Catostomidae and all cyprinid subfamilies, except for the Psilorhynchinae and two developmentally truncated genera, Danionella and Paedocypris. In addition to these two cypriniforme families, the long intercostal ligament is homoplastically present in some catfishes. Given the topology of Saitoh et al. (2011) , presence of the long intercostal ligament is a synapomorphy of Cyprinidae+Catostomidae. Some shorter ligaments are also present in the Cypriniformes and Chilodus gracilis (Characiformes), near the base of the anterior ribs and only occurring anterodorsally to the putative line of the long intercostal ligament even when it is absent.     

Complete mitochondrial genome of the grass carp (Ctenopharyngodon idella, Teleostei): insight into its phylogenic position within Cyprinidae

Genome comparison has shed light on many fields of both basic and applied research, including the study of species phylogeny. Grass carp (Ctenopharyngodon idella) belongs to Cyprinidae, the largest freshwater fish family; but which subfamily it belongs to remains a controversial issue. In this study, the complete mitochondrial genome (mitogenome) sequence of grass carp was determined and phylogenetic analyses of all mitochondrial protein-coding genes and a nuclear gene (RAG 2) were conducted to explore the evolutionary relationship of grass carp with other cyprinid species. The mitogenome of grass carp is 16,609 bp in length. As with most other vertebrates, it contains the same gene order and an identical number of genes or regions, including 13 protein-coding genes, two rRNA genes, 22 tRNA genes and one putative control region. Phylogenetic analyses using two different datasets (mitochondrial and nuclear) and three different computational algorithms (Bayesian, MP and ML) all revealed two distinct groups with high statistical support, indicating that Cyprininae and Leuciscinae are two separate, valid subfamilies. Importantly, our phylogenetic result provides strong molecular evidence in support of the placement of Ctenopharyngodon in Leuciscinae rather than in Cyprininae.     

指环虫属的早期辐射及其与宿主鲤科鱼类的协同进化关系

本研究利用28SrDNAC1-D2区序列分析采自鲤科鱼类中6亚科宿主和寄生在花鲈、梅花鲈上的共17种指环虫的系统发育关系。同时,通过比较宿主鲤科鱼类与指环虫的系统发育树,检验指环虫与其宿主是否存在协同进化关系。结果表明:17种指环虫形成5个进化支(Clade),其中寄生在团头鲂(亚科)和鲢、鳙(鲢亚科)上的6种指环虫聚为一支(Clade1),而它们的宿主鱼类在系统发育分析中也表现为近缘关系;寄生在鲮鱼(野鲮亚科)上的D.quanfami(Clade5)位于系统树最基部,鲫鱼和鲤鱼(鲤亚科)的寄生指环虫处在系统树的次基部位置,而鲤亚科与野鲮亚科组成的姐妹群在宿主系统树上同样处在基部位置,寄生虫和宿主在进化上较为原始的地位得到了很好地相互印证。因而,本研究首次利用分子系统学手段分析指环虫属远缘物种间的系统关系,揭示了指环虫属与宿主鱼类之间存在协同进化关系。另外,本研究首次发现,野鲮亚科鱼类也可能是指环虫类的早期宿主,这与先前认为鲤亚科鱼类为指环虫类的祖先宿主的推测有所不同。     

Remarkable phylogenetic resolution of the most complex clade of Cyprinidae (Teleostei: Cypriniformes): A proof of concept of homology assessment and partitioning sequence data integrated with mixed model Bayesian analyses

Despite many efforts to resolve evolutionary relationships among major clades of Cyprinidae, some nodes have been especially problematic and remain unresolved. In this study, we employ four nuclear gene fragments (3.3 kb) to infer interrelationships of the Cyprinidae.A reconstruction of the phylogenetic relationships within the family using maximum parsimony, maximum likelihood, and Bayesian analyses is presented. Among the taxa within the monophyletic Cyprinidae, Rasborinae is the basal-most lineage; Cyprinine is sister to Leuciscine. The monophyly for the subfamilies Gobioninae, Leuciscinae and Acheilognathinae were resolved with high nodal support. Although our results do not completely resolve relationships within Cyprinidae, this study presents novel and significant findings having major implications for a highly diverse and enigmatic clade of East-Asian cyprinids. Within this monophyletic group five closely-related subgroups are identified. Tinca tinca, one of the most phylogenetically enigmatic genera in the family, is strongly supported as having evolutionary affinities with this East-Asian clade; an established yet remarkable association because of the natural variation in phenotypes and generalized ecological niches occupied by these taxa.Our results clearly argue that the choice of partitioning strategies has significant impacts on the phylogenetic reconstructions, especially when multiple genes are being considered. The most highly partitioned model (partitioned by codon positions within genes) extracts the strongest phylogenetic signals and performs better than any other partitioning schemes supported by the strongest 2Δln Bayes factor. Future studies should include higher levels of taxon sampling and partitioned, model-based analyses.     

Phylogenetic relationships of Iberian cyprinids: systematic and biogeographical implications.

The phylogenetic relationships among all Iberian endemic cyprinids were inferred using the complete nucleotide sequence of the cytochrome b gene. The inferred molecular phylogeny included representatives from Central European, Asian and North African species, and is highly congruent with previous phylogenies based on osteological characters. Iberian cyprinids were grouped into only five, very speciose lineages (with the exception of the monotypic Anaecypris): Barbus, Luciobarbus, Chondrostoma, Leuciscus and Anaecypris. The existence of such a relatively small number of Iberian cyprinid lineages can be explained by the historical isolation of the Iberian Peninsula. North African and Asian barbels are the sister group of Iberian Luciobarbus, supporting a south-eastern route of colonization of the Iberian Peninsula for this subgenus. With leuciscins, Anaecypris hispanica was considered a relict species as it could not be related to any other Iberian cyprinid. The phylogenetic relationships among the main lineages of Iberian cyprinids based on cytochrome b sequence data supported the traditional division of the Cyprinidae into two subfamilies: Cyprininae and Leuciscinae.     

S7核糖体蛋白基因序列变异与(鱼丹)亚科鱼类的单系性研究

使用分子生物学的方法对Dan亚科鱼类的单系性进行了探讨。通过PCR方法,获得了13种鲤科鱼类S7核糖体蛋白基因第1内含子序列,其中包括6种Dan亚科鱼类。使用MEGA软件中的Neighbor-Joining法和Most-Parsimony法分别构建分支系统图。研究结果显示目前所确认的Dan亚科鱼类实际上没有形成单系类群。其中Dan属、波鱼属和低线Lie属位于系统树基部,显示出原始性,而由细鲫属、马口鱼属和Lie属构成的类群相对于Dan亚科中的原始种类起源较晚,可能和较晚起源的东亚鲤科类群之间有更为密切的关系。     

Genus-level supertree of Cyprinidae (Actinopterygii: Cypriniformes), partitioned qualitative clade support and test of macro-evolutionary scenarios

We used the supertree approach of matrix representation with parsimony to reconstruct to date the most exhaustive (genus‐level) phylogeny of Cyprinidae. The supertree of Cyprinidae, representing 397 taxa (237 nominal genera) and 990 pseudocharacters, was well resolved (96%) through extended consensus majority rule, although 36 nodes (9.4%) were unsupported. The proportion of shared taxa among source trees was very low after calculation of the taxonomic coverage index (TCI = 0.059), which is proposed here as a more accurate alternative to the usual ratios calculated from the number of pseudo‐characters or source trees per taxon. We define a new index for the calculation of partitioned qualitative clade support, the partitioned rQS (_prQS), which offers a straightforward visualization of the relative supports of source tree partitions at supertree nodes.The use of _prQS showed that the molecular source tree partition contributed to most node supports within the supertree of Cyprinidae (73%, contra 21% for the morphological partition) and evidenced a fair proportion of conflict at nodes between the two partitions (21%), notably reflecting (i) the greater number and resolution of molecular source trees, and (ii) potential morphological convergences. Most of the higher‐level relationships within Cyprinidae were supported by both morphological and molecular source tree partitions. Our supertree showed a well‐supported dichotomy between a clade consisting of a ‘barbine’ + ‘rasborine’ lineage, sister group to (Barbinae [paraphyletic], (Cyprininae, Labeoninae)), and a clade consisting of other rasborines (large polytomy) and the two monophyletic groups ((Tincinae, Tanichthys), (Ecocarpia, (Acheilognathinae, (Gobioninae, Leuciscinae)))) and (Squaliobarbinae, (Xenocyprinae, Cultrinae)). Through the non‐monophyly of almost all the traditional subfamilies of Cyprinidae and 34 genera, our supertree exemplified the taxonomic chaos that reigns in the classification of the family. It also highlighted that further efforts should aim at increasing taxonomic sampling and generating alternative phylogenetic signals, notably for the still poorly apprehended Tincinae, Squaliobarbinae, Acheilognathinae, Gobioninae, and Rasborinae, the latter representing a key taxon for the understanding of early cyprinid evolution. Our supertree also proved useful for testing macro‐evolutionary scenarios at a wide taxonomic scale. Ancestral reconstructions using linear parsimony confirmed that the Oriental tropical region was the centre of origin of Cyprinidae, and identified three Oriental‐to‐Palaearctic, two Palaearctic‐to‐Nearctic, and one Oriental‐to‐Afrotropical major migration events. On the other hand, we almost completely rejected the hypothesis of presence of barbels as a plesiomorphic condition within Cyprinidae (although ambiguous for maxillary barbels of the Barbinae‐Cyprininae type). The supertree of Cyprinidae serves as a basis to discuss the applications and bias of the newly proposed _prQS, to provide future guidelines for a better achievement of cyprinid phylogeny, and to elaborate further on inter‐continental migrations and the adaptive value of barbels.     

Phylogeny and biogeography of highly diverged freshwater fish species (Leuciscinae,Cyprinidae, Teleostei) inferred from mitochondrial genome analysis

The distribution of freshwater taxa is a good biogeographic model to study pattern and process of vicariance and dispersal. The subfamily Leuciscinae (Cyprinidae, Teleostei) consists of many species distributed widely in Eurasia and North America. Leuciscinae have been divided into two phyletic groups, leuciscin and phoxinin. The phylogenetic relationships between major clades within the subfamily are poorly understood, largely because of the overwhelming diversity of the group. The origin of the Far Eastern phoxinin is an interesting question regarding the evolutionary history of Leuciscinae. Here we present phylogenetic analysis of 31 species of Leuciscinae and outgroups based on complete mitochondrial genome sequences to clarify the phylogenetic relationships and to infer the evolutionary history of the subfamily.     

Molecular phylogeny of the freshwater fish family Cobitidae (Cypriniformes: Teleostei): delimitation of genera, mitochondrial introgression and evolution of sexual dimorphism

The family Cobitidae represents a characteristic element of the Eurasian ichthyofauna. Despite diverse features of sexual dimorphism, comparably few morphological characters have been utilized for taxonomic studies resulting in many unresolved puzzles. Here we present the phylogenetic relationships of Cobitidae as inferred from the mitochondrial cytochrome b gene and the nuclear gene RAG-1. Analyses of both markers show a group of eight nominal genera, which all occur in Europe and eastern, northern and western Asia, forming a monophyletic lineage (northern clade) while all other clades inhabit South and Southeast Asia (southern lineages). While all eight southern lineages correspond to genera as defined by morphological studies, only four lineages were reliably recovered within the northern clade, and of these only one (Sabanejewia) corresponds to a formerly considered genus. The genera Cobitis, Iksookimia and Niwa?lla were polyphyletic. A comparison of the two markers shows several incongruities within the northern clade and mitochondrial introgression at least in the genus Misgurnus. Mapping the characters of sexual dimorphism on our cladogram, we identified five character states that are diagnostic for certain lineages. Estimations of the divergence times dated the separation of the northern clade from the southern lineages to the middle Eocene (46 MYA) and the origin of "Cobitis"misgurnoides, the basal taxon of the northern clade, during early Oligocene (30-35 MYA). The geographic distribution of the major clades supports recently developed hypotheses about the river history of East Asia and further suggests that a range expansion of the northern clade in late Miocene (15 MYA) led to the colonisation of Europe by three already distinct genera.     

Plate tectonics and biogeographical patterns of the Pseudophoxinus (Pisces: Cypriniformes) species complex of central Anatolia, Turkey

We investigated the phylogenetic relationships of Pseudophoxinus (Cyprinidae: Leuciscinae) species from central Anatolia, Turkey to test the hypothesis of geographic speciation driven by early Pliocene orogenic events. We analyzed 1141 aligned base pairs of the complete cytochrome b mitochondrial gene. Phylogenetic relationships reconstructed by maximum likelihood, Bayesian likelihood, and maximum parsimony methods are identical, and generally well supported. Species and clades are restricted to geologically well-defined units, and are deeply divergent from each other. The basal diversification of central Anatolian Pseudophoxinus is estimated to have occurred approximately 15 million years ago. Our results are in agreement with a previous study of the Anatolian fish genus Aphanius that also shows a diversification pattern driven by the Pliocene orogenic events. The distribution of clades of Aphanius and Pseudophoxinus overlap, and areas of distribution comprise the same geological units. The geological history of Anatolia is likely to have had a major impact on the diversification history of many taxa occupying central Anatolia; many of these taxa are likely to be still unrecognized as distinct.     

鲴亚科分子系统学研究

为探讨鲴亚科(Xenocyprinae)鱼类系统发育关系,研究基于2种线粒体基因和5种核基因序列对鲴亚科各物种的系统发育关系和分化时间进行评估。结果显示:不同方法和数据类型获得了基本一致的拓扑结构。3个属的单系性都得到了很好地支撑;但是,它们之间的进化关系却随着分子标记的不同而改变。这一结果可能是由于早期的基因流或谱系的随机分选所致。此外,银鲴(Xenocypris argentea)、云南鲴(Xenocypris yunnanensis)和黄尾鲴(Xenocypris davidi)之间呈现出嵌套型的谱系关系,暗示它们之间存在基因交流的可能性。基于化石地层年代校正的分子钟估算结果显示,鲴亚科主要类群的分化发生在中新世晚期,约15—12百万年前(Millions of years ago, Ma),这与东亚季风强盛时期的时间相吻合。     

A study of the systematics of cyprinid fishes by two-dimensional gel electrophoresis

This study was carried out to shed light on confused subfamilial groupings in the Cyprinidae from the biochemical viewpoint at the molecular level, specifically by using two-dimensional gel electrophoresis of liver proteins. Six pairs of cypriniform fishes, which are different from one another at familial, subfamilial, generic, specific, subspecific, and individual levels, were compared. The genetic distances between pairs of fishes increased as taxonomic ranks of the pairs became higher, confirming the reliable usefulness of this technique. Four species representing the different subfamilies, Cyprininae, Gobioninae, Acheilognathinae, and Leuciscinae, were compared to give new insight into relationships at the subfamilial level. Cyprinus carpio (Cyprininae) and Pseudogobio esocinus esocinus (Gobioninae) gave the smallest genetic distance and the largest values were obtained between either one of the above species and Acheilognathus melanogaster (Acheilognathinae), suggesting that the former two subfamilies compose the most closely related group that is in turn distantly related to Acheilognathinae. Tribolodon hakonensis (Leuciscinae) had almost equal genetic distances to the three other species.