Nuclear Ribosomal ITS Functional Paralogs Resolve the Phylogenetic Relationships of a Late-Miocene Radiation Cycad Cycas (Cycadaceae)

Cycas is the most widespread and diverse genus among the ancient cycads, but the extant species could be the product of late Miocene rapid radiations. Taxonomic treatments to date for this genus are quite controversial, which makes it difficult to elucidate its evolutionary history. We cloned 161 genomic ITS sequences from 31 species representing all sections of Cycas. The divergent ITS paralogs were examined within each species and identified as putative pseudogenes, recombinants and functional paralogs. Functional paralogs were used to reconstruct phylogenetic relationships with pseudogene sequences as molecular outgroups, since an unambiguous ITS sequence alignment with their closest relatives, the Zamiaceae, is unachievable. A fully resolved and highly supported tree topology was obtained at the section level, with two major clades including six minor clades. The results fully supported the classification scheme proposed by Hill (2004) at the section level, with the minor clades representing his six sections. The two major clades could be recognised as two subgenera. The obtained pattern of phylogenetic relationships, combined with the different seed dispersal capabilities and paleogeography, allowed us to propose a late Miocene rapid radiation of Cycas that might have been promoted by vicariant events associated with the complex topography and orogeny of South China and adjacent regions. In contrast, transoceanic dispersals might have played an important role in the rapid diversification of sect. Cycas, whose members have evolved a spongy layer in their seeds aiding water dispersals.     

Phylogeography of the piranha genera Serrasalmus and Pygocentrus: implications for the diversification of the Neotropical ichthyofauna

The phylogenetic relationships within the piranhas were assessed using mitochondrial sequences with the aim of testing several hypotheses proposed to explain the origin of Neotropical diversity (palaeogeography, hydrogeology and museum hypotheses). Sequences of the ribosomal 16S gene (510 bp) and control region (980 bp) were obtained from 15 localities throughout the main South American rivers for 21 of the 28 extant piranha species. The results indicate that the genus Serrasalmus is monophyletic and comprises three major clades. The phylogeographical analyses of these clades allowed the identification of five vicariant events, extensive dispersal and four lineage duplications suggesting the occurrence of sympatric speciation. Biogeographical patterns are consistent with the prediction made by the museum hypothesis that lineages from the Precambrian shields are older than those from the lowlands of the Amazon. The vicariant events inferred here match the distribution of the palaeoarches and several postdispersal speciation events are identified, thereby matching the predictions of the palaeogeography and hydrogeology hypotheses, respectively. Molecular clock calibration of the control region sequences indicates that the main lineages differentiated from their most recent common ancestor at 9 million years ago in the proto Amazon-Orinoco and the present rate of diversification is the highest reported to date for large carnivorous Characiformes. The present results emphasize that an interaction among geology, sea-level changes, and hydrography created opportunities for cladogenesis in the piranhas at different temporal and geographical scales.     

Secondary structure prediction of ITS rRNA region and molecular phylogeny: an integrated approach for the precise speciation of <Emphasis Type="Italic">Muscodor</Emphasis> species

Muscodor is a non-sporulating, volatile organic compounds producing endophytic fungi that has been extensively explored as a bio-fumigant and bio-preservative. Novel species of this genus have been mainly identified using ITS sequences. However, the ITS hyper-variability hinders the creation of reproducible alignments and stable phylogenetic trees. Conserved structural data of the ITS region represents as a vital auxiliary information for accurate speciation of fungi. In the present study, secondary structural data of ITS1, 5.8S, and ITS2 region of all Muscodor species were generated using LocaRNA web server. The predicted secondary structural data displayed greater variability in ITS1 region in comparison to ITS2. The structural data of all sequences exhibited characteristic conserved features of eukaryotic rRNA. Evolutionary conserved motifs were found among all 5.8S and ITS2 sequences. Profile neighbor joining (PNJ) tree based on combined sequence-structural information of ITS region was generated in ProfDists. The PNJ tree resolved into four major groups whereby M. fengyangenesis and M. albus species formed monophyletic clades. However, three M. albus species along with other Muscodor species emerged as sister branches to the existing clades, thereby, improving the precision of phylogenetic analysis for identification of novel species of Muscodor genus. Hence, the results indicated that structural analysis along with primary sequence information can provide new insights for precise identification of Muscodor species.     

Phylogenetic relationships among populations of the Nacobbus aberrans (Nematoda,Pratylenchidae) complex reveal the existence of cryptic species

The plant‐parasitic nematode Nacobbus aberrans sensu lato is an agricultural pest of quarantine importance. Due to the morphometric, physiological and genetic variability observed within the species, there is no agreement on the taxonomy of this nematode. The objective of this study was to analyse the ITS rDNA region and the D2–D3 expansion segments of 28S rDNA in 10 Argentine populations and one from Ecuador and to establish their phylogenetic relationship with other known sequences from South and North America. Phylogenetic trees of the ITS gene showed seven statistically well‐supported clades; the high and significant F_st values obtained among these groups confirmed this partitioning. The Argentine populations here considered were separated into three clades: one comprising a population from the Andean region and two grouping nematodes from lower altitudes. Three other clades were distinguished for South American populations, which included known sequences of individuals from Peru, Bolivia and north of Argentina. The other clade included sequences from Mexico, Ecuador and two Argentine populations of unknown origin. The important degree of genetic divergence observed among Andean populations suggests that the Andes may have played a crucial role in speciation of Nacobbus, which would have originated in this region. Although D2–D3 segments exhibited lower variation, they were useful for establishing phylogenetic relationships among the Argentine populations considered in this work. As there are no other GenBank sequences available for these segments, it was not possible to make comparisons with other populations from South and North America. The considerable genetic differentiation observed in ITS rDNA region among Nacobbus populations showed evidence of cryptic species within the N. aberrans s.l. complex. Integration of morphological and morphometric studies and molecular analyses considering other genes may aid in the identification of species and their phylogenetic relationships within this genus.     

Island-like radiation of Saussurea (Asteraceae: Cardueae) triggered by uplifts of the Qinghai–Tibetan Plateau

Increasing evidence suggests that geological or climatic events in the past triggered the radiative diversification of both animals and plants on islands as well as continents. The Qinghai–Tibetan Plateau (QTP) has been extensively uplifted since the Miocene, but there is little information on possible links between these events and biological diversification in this and adjacent regions. Partly to explore such links, we have examined the diversification of Saussurea (Asteraceae: Cardueae), a species-rich genus that is mostly endemic to QTP, but also occurs in arid highlands elsewhere in the Northern Hemisphere. The phylogenetic analyses were conducted on the basis of the nuclear (internal transcribed spacer, ITS) and plastid ( trnL-F and psbA-trnH ) sequences from 55 species, representing 19 sections from all six subgenera of Saussurea , and species from 15 genera of the Cardueae. The results suggest that the currently circumscribed genus Saussurea ( s.l. ) is a polyphyletic group and that five sections should be excluded from the genus. Samples from the other 14 sections (representing five subgenera) clustered as a monophyletic group (here designated the Saussurea s.s. lineage, SSSL) with high statistical support. However, none of the analyses (nuclear, plastid or combined) resolved SSSL's infrageneric phylogeny, and the parallel clades of the lineage indicate that island-like adaptive radiation occurred. Furthermore, this radiation appears to have occurred 14–7 Mya, during the period of the major uplift events of QTP. Thus, our results support the hypothesis that geological events may play important roles in driving biological diversification through continental radiation.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 893–903.     

Phylogeny of Crocus (Iridaceae) based on one chloroplast and two nuclear loci: Ancient hybridization and chromosome number evolution

Crocus consists of about 100 species distributed from western Europe and northern Africa to western China, with the center of diversity on the Balkan Peninsula and in Asia Minor. Our study focuses on clarifying phylogenetic relationships and chromosome number evolution within the genus using sequences of the chloroplast trnL-F region, the nuclear ribosomal DNA internal transcribed spacer (ITS) region, and a part of the nuclear single-copy gene pCOSAt103.In a combined dataset of ITS and trnL-F sequences, 115 individuals representing 110 taxa from both subgenera and all sections and series of Crocus were analyzed with Bayesian phylogenetic inference. For pCOSAt103 79 individuals representing 74 Crocus taxa were included, and for the majority of them PCR amplicons were cloned and up to eight clones per individual were sequenced to detect allopolyploidization events. Romulea species were included as outgroup in both analyses. Characteristics of seed surface structures were evaluated by scanning electron microscopy.Phylogenetic analysis of ITS/trnL-F data resulted in a monophyletic genus Crocus, probably monophyletic sections Crocus and Nudiscapus, and inferred monophyly for eight of the 15 series of the genus. The C. biflorus aggregate, thought to be consisting of closely related subspecies, was found to be polyphyletic, the taxa occurring within three major clades in the phylogenetic tree. Cloning of pCOSAt103 resulted in the detection of homoeologous copies in about one third of the taxa of section Nudiscapus, indicating an allotetraploid origin of this section. Reconstruction of chromosome number evolution along the phylogenetic tree using a probabilistic and a parsimony approach arrived at partly contradictory results. Both analyses agreed however on the occurrence of multiple polyploidization and dysploidy events. B chromosomes evolved at least five times independently within the genus, preferentially in clades characterized by karyotype changes.     

基于序列trnL-trnF和ITS的榉属系统发育与地理分布格局的初步分析

榉属(Zelkova)是包含6个种的榆科小属, 呈东亚、西亚和南欧间断分布。该文基于DNA序列trnL-trnF和ITS构建了榉属的分子系统发育树, 大体上把此属分为3个分支, 分别对应东亚、西亚和南欧的种类, 与前人仅依据ITS序列的结果不同。生物地理的扩散和隔离分化分析(DIVA)表明, 榉属的原始祖先分布区可能是欧亚北温带, 包括了东亚、西亚和南欧的某个大的区域。分化过程以隔离分化为主要特征, 即3个分布区域是逐步隔离分化的。由于东亚的物种多样性, 北太平洋有可能是起源中心。榉属的现代分布格局可能主要是由于渐新世发生的古地中海西退、中新世发生的青藏高原大范围隆升, 以及第四纪冰川活动引起的分布区的收缩。     

Phylogenetic analysis of Hordeum (Poaceae) as inferred by nuclear rDNA ITS sequences

Hordeum (Poaceae, Triticeae) occurs with 31 species worldwide in temperate regions, with the exception of Australasia. About 50% of the species are polyploids (4x, 6x) or occur as di- and polyploid forms. To analyze the phylogenetic relationships among diploid and polyploid taxa of the genus the nuclear rDNA internal transcribed spacer region (ITS) was analyzed for 91 accessions, representing all Hordeum species, together with 10 outgroup species. PCR products were either directly sequenced (outgroups) or cloned and eight clones per individual were analyzed. Phylogenetic analysis revealed four major clades that concur with the four genome groups in Hordeum (H, I, Xa, and Xu). Allopolyploids, putative autopolyploids, and species groups within the closely related H-genome clade could be identified. The ITS data indicate times of independent evolution of paralogous rDNA clusters on different chromosomes intermitted by sweeps of homogenization among these clusters and bi-directional homogenization of the clusters in diploids. Penalized likelihood analysis revealed an age of about 12 million years (my) for the genus and indicated the start of a rapid radiation in the H-genome group about 2.5 my ago in South America and Asia.     

Phylogenetic relationships in Gleditsia (Leguminosae) based on ITS sequences

We used nucleotide sequences from the internal transcribed spacers and 5.8S gene of nuclear ribosomal DNA to test competing phylogenetic and biogeographic hypotheses in Gleditsia. Eleven of 13 Gleditsia species were sampled, along with two species of its sister genus, Gymnocladus. Analyses of ITS data and of a combined data set that included sequences of ITS and two chloroplast genes supported several conclusions that were interpreted in light of fossil data and current legume phylogeny. Gleditsia and Gymnocladus appear to have originated in eastern Asia during the Eocene. Eastern North American species of both genera most likely evolved from ancestors that migrated across the Bering land bridge, but the eastern Asian/eastern North American disjunction appears to be much older in Gymnocladus than in Gleditsia. Gleditsia amorphoides, from temperate South America, is sister to the rest of the genus, suggesting early long-distance dispersal from Asia. The remainder of Gleditsia is divided into three unresolved clades, possibly indicating a split early in the evolution of the genus. Two of those clades contain only Asian species, and one contains Asian and North American species. The North American species, Gleditsia triacanthos and Gleditsia aquatica, are polymorphic and paraphyletic with respect to their ITS and cpDNA sequences, which suggests recent diversification.     

Molecular phylogeny of species of Ligophorus (Monogenea: Dactylogyridae) and their affinities within the Dactylogyridae

The taxonomic framework of Ligophorus, monogenean specialists of the gills of grey mullets (Mugilidae), is evaluated and its interspecific relationships are assessed for the first time using molecular data. The position of Ligophorus within the paraphyletic Ancyrocephalinae is re-assessed based on newly sequenced species. Furthermore, the relationship between morphometric and genetic interspecific similarities is evaluated. Partial 28S and complete ITS1 rDNA sequences from representatives of 14 of the 16 nominal species of Ligophorus from the Mediterranean, Black and Azov Seas were analysed together with published sequences of members of the Dactylogyridae. The phylogenetic analyses of the Dactylogyridae (i) confirmed the position of Ligophorus within the marine Ancyrocephalinae; (ii) revealed a sister relationship between Ergenstrema and Ligophorus, whose species are all exclusive parasites of grey mullets; and (iii) substantiated the affinities of Ergenstrema with the marine Ancyrocephalinae. The phylogenetic analysis restricted to Ligophorus confirmed the distinct status of the included species. The ITS1 region provided the highest divergence between species and phylograms with the strongest branch support. Both the 28S and ITS1 phylograms revealed two main clades. One included species from hosts with Mediterranean and NE Atlantic distribution and another was formed by species parasitising several Liza spp., including Lz. haematocheilus from the Northwestern Pacific, and Mugil cephalus, which suggests an origin outside the Mediterranean for the latter clade. The phylogenetic evidence presented herein indicated that a combination of host-switching and lineage duplication events accounted for the diversification of this genus in the Mediterranean basin. The agreement between molecular and morphological interspecific similarities observed in Ligophorus supports the validity of morphometric characters used for species identification.     

Molecular analyses of the genus Ilex (Aquifoliaceae) in southern South America, evidence from AFLP and ITS sequence data

In order to clarify the relationships among southern South American (sSA) representatives of the genus Ilex, an amplified fragment length polymorphism (AFLP) analysis was accomplished. In addition, the phylogenetic relationships of the species were studied using ribosomal internal transcribed spacer (ITS) sequence data alone and in combination with AFLP data, taking into account the possible existence of paralogous sequences and the influence of alignment parameters. To explore stability of phylogenetic hypotheses, a sensitivity analysis was performed using 15 indel-substitution models. Within each species assayed, the AFLPs allowed the recognition of several diagnostic bands. Furthermore, the AFLP analysis revealed that individuals belonging to the same morpho-species formed coherent clades. In addition, some cases of geographical association were noted. Studies on ITS sequences revealed divergence between data obtained herein and sequence data downloaded from GenBank. The sensitivity analyses yielded different interspecific hypotheses of relationships. Notwithstanding, analyses of the ITS data alone and in combination with AFLPs, rendered clades stable to variation in the analytical parameters. Topologies obtained for the AFLPs, the ITS data alone and the combined analyses, demonstrated the existence of a group formed by I. argentina, I. brasiliensis, I. brevicuspis, I. integerrima, and I. theezans, and that I. dumosa and I. paraguariensis were distantly related to the former. Incongruence with traditional taxonomical treatments was found.     

Biogeography of the Lizard Genus Tropidurus Wied-Neuwied, 1825 (Squamata: Tropiduridae): Distribution,Endemism, and Area Relationships in South America

Based on comprehensive distributional records of the 23 species currently assigned to the lizard genus Tropidurus, we investigated patterns of endemism and area relationships in South America. Two biogeographic methods were applied, Parsimony Analysis of Endemicity (PAE) and Brooks Parsimony Analysis (BPA). Two areas of endemism were detected by PAE: the first within the domains of the semiarid Brazilian Caatinga, which includes seven endemic species, and the second in the region of the Serranía de Huanchaca, eastern Bolivia, in which three endemic species are present. The area cladograms recovered a close relationship between the Atlantic Forest and areas of the South American open corridor. The results revealed a close relationship among the provinces Caatinga (Cerrado, Parana Forest (Pantanal+Chaco)). The uplift of the Brazilian Central Plateau in the Late Pliocene-Early Pleistocene (4-2 Myr BP) has been interpreted as a major event responsible for isolation and differentiation of biotas along these areas. However, we emphasize that without the establishment of a temporal framework concerning the diversification history of Tropidurus it is premature to correlate cladogenetic events with specific time periods or putative vicariant scenarios. The limiting factors hampering the understanding of the biogeographic history of this genus include (1) the absence of temporal references in relation to the diversification of distinct clades within Tropidurus; (2) the lack of an appropriate taxonomic resolution of the species complexes currently represented by widely distributed forms; and (3) the need for a comprehensive phylogenetic hypothesis. We suggest that these three important aspects should be prioritized in future investigations.     

Molecular phylogeny of Sinocyclocheilus (Cypriniformes: Cyprinidae) inferred from mitochondrial DNA sequences

More than 10 species within the freshwater fish genus Sinoncyclocheilus adapt to caves and show different degrees of degeneration of eyes and pigmentation. Therefore, this genus can be useful for studying evolutionary developmental mechanisms, role of natural selection and adaptation in cave animals. To better understand these processes, it is indispensable to have background knowledge about phylogenetic relationships of surface and cave species within this genus. To investigate phylogenetic relationships among species within this genus, we determined nucleotide sequences of complete mitochondrial cytochrome b gene (1140 bp) and partial ND4 gene (1032 bp) of 31 recognized ingroup species and one outgroup species Barbodes laticeps. Phylogenetic trees were reconstructed using maximum parsimony, Bayesian, and maximum likelihood analyses. Our phylogenetic results showed that all species except for two surface species S. jii and S. macrolepis clustered as five major monophyletic clades (I, II, III, IV, and V) with strong supports. S. jii was the most basal species in all analyses, but the position of S. macrolepis was not resolved. The cave species were polyphyletic and occurred in these five major clades. Our results indicate that adaptation to cave environments has occurred multiple times during the evolutionary history of Sinocyclocheilus. The branching orders among the clades I, II, III, and IV were not resolved, and this might be due to early rapid radiation in Sinocyclocheilus. All species distributed in Yunnan except for S. rhinocerous and S. hyalinus formed a strongly supported monophyletic group (clade V), probably reflecting their common origins. This result suggested that the diversification of Sinocyclocheilus in Yunnan may correlate with the uplifting of Yunnan Plateau.     

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.     

Additive polymorphisms and reticulation in an ITS phylogeny of thrifts (Armeria,Plumbaginaceae)

A parsimony analysis of 133 sequences of the nuclear ribosomal DNA ITS1+5.8S+ITS2 region from 71 taxa in Armeria was carried out. The presence of additive polymorphic sites (APS; occurring in 14 accessions) fits the reticulate scenario proposed in previous work for explaining the ITS pattern of variation on a much smaller scale and is based mainly on the geographical structure of the data, irrespective of taxonomic boundaries. Despite the relatively low bootstrap values and large polytomies, part of which are likely due to disruptive effects of reticulation and concerted evolution in these multicopy sequences, the ITS analysis has phylogenetic and biogeographic implications. APS detected in this study are consistent with hypothesized hybridization events, although biased concerted evolution, previously documented in the genus, needs to be invoked for specific cases and may be responsible for a possible "sink" effect in terminals from a large clade. The causes for sequences of the same species appearing in different clades (here termed transclade) are discussed.     

Molecular evidence for the compilospecies model of reticulate evolution in Armeria (Plumbaginaceae)

Cladistic analyses of the nuclear ribosomal DNA (nrDNA) internal transcribed spacer (ITS) sequences from 55 samples corresponding to 34 taxa in the genus Armeria reveal that ITS sequence diversity among and within species utterly conflicts with patterns of morphological similarity. Three facts are apparent from the results here reported: (1) different samples of a single subspecies, A. villosa subsp. longiaristata, appear in three of the five major clades; (2) samples of at least one of the six subspecies of A. villosa appear in four of the five major clades; and (3) the composition of major clades shows greater congruence with the geographic origin of plants than with the traditional systematic arrangement based primarily on morphology. Specifically, the clades here termed Ia, II, III, and IV each encompass terminals restricted to geographically delimited areas. There are alternative explanations for the ITS pattern, but the most likely one is that nucleotide positions supporting the major clades are due, in some of the samples, to concerted evolution following horizontal transfer (gene flow) rather than to recency of common ancestry. This interpretation is consistent with previous systematic and experimental evidence and implies that reticulation in Armeria may be extensive. Harlan and de Wet (1963, Evolution 17:497-501) proposed the compilospecies concept to account for situations in which a genetically "aggressive" species captures portions of the genome of other sympatric species by means of extensive introgression. Evidence of extensive reticulation, ecological diversification, and geographic pattern indicates that A. villosa may fit the compilospecies concept, which is here supported on molecular grounds for the first time.     

Species tree phylogeny,character evolution,and biogeography of the Patagonian genus <Emphasis Type="Italic">Anarthrophyllum</Emphasis> Benth. (Fabaceae)

Geologic events promoting the aridization of southern South America contributed to lineage divergences and species differentiation through geographic (allopatric divergence) and biotic and abiotic factors (ecological divergence). For the genus Anarthrophyllum, which is distributed in arid and semi-arid regions of Patagonia, we assessed how these factors affected species diversification and reconstructed its possible biogeographic history in South American arid environments. Sequences were obtained from two molecular markers: the ITS nuclear region and the trnS-trnG plastid region. Using Parsimony, Maximum likelihood and Bayesian inference individual gene trees were reconstructed, and a species tree was obtained using multi-species coalescent analysis. Divergence times among species were estimated using secondary calibrations. Flexible Bayesian models and stochastic character mapping were used to elucidate ancestral geographic distributions and the evolution of the floral and vegetative phenotypes in the genus. Gene trees and species tree analyses strongly support Anarthrophyllum as monophyletic; all analyses consistently retrieved three well-supported main clades: High Andean Clade, Patagonian Clade 1, and Patagonian Clade 2. Main diversification events occurred concomitant with the Andean uplift and steppe aridization; the Andean mountain range possibly acted as a species barrier for the High Andean Clade. Vegetative traits showed adaptations to harsh climates in some clades, while pollinator-related floral features were associated with independent diversification in bee- and bird-pollinated clades within both Patagonian Clades. In conclusion, evolutionary and biogeographic history of Anarthrophyllum resulted from the action of ecological, historical, and geographic factors that acted either alternatively or simultaneously.     

The phylogeny of Schistidium (Bryophyta, Grimmiaceae) based on primary and secondary structure study of nuclear rDNA internal transcribed spacers

The phylogeny of Schistidium (Bryophyta, Grimmiaceae) was studied on the basis of nucleotide sequences of internal transcribed spacers ITS1-2 of nuclear DNA and trnT-trnD region of chloroplast DNA. The consistency of phylogenetic trees constructed from nuclear and chloroplast sequences was shown. A basal grade and two large clades were resolved on the phylogenetic trees. Morphological characteristics specific for these clades were described. ITS1 and ITS2 secondary structures of Schistidium species were modeled using thermodynamic criteria. Four different structures of the longest ITS1 hairpin were identified. Possible paths of Schistidium evolution were considered based on the four types of ITS1 secondary structure and phylogenetic trees.     

线粒体D-loop序列变异与东方鲀属鱼类系统发育

东方鲀属的红鳍东方鲀（Takifugu rubripes）是后基因组时代的一种重要模式生物。本研究中,利用东方鲀属11种鱼类（18尾）的D-loop基因序列,对东方鲀属鱼类的系统发育关系进行研究。经序列比对排定后,分析中D-loop序列有841个位点,其中395个位点为可变位点,267个位点为系统发育信息位点。分别采用邻接法（NJ）、最大简约法（MP）、最大似然法（ML）和贝叶斯方法构建了分子系统树。研究结果表明：（1）东方鲀属鱼类为一单系类群;（2）由横纹东方鲀（T. oblongus）和铅点东方鲀（T. alboplumbeus）构成的姊妹群位于这个类群的基部。此外,本属鱼类物种分类现状还需要进一步的澄清。