Evolution of monogenean parasites across vertebrate hosts illuminated by the phylogenetic position of Euzetrema Combes, 1965 within the Monopisthocotylea

The Monogenea, which is divided into two clades, namely the Monopisthocotylea and Polyopisthocotylea, is a highly diversified group of platyhelminth parasites that infest mainly actinopterygian and chondrichthyan fishes but also, to a lesser extent, freshwater sarcopterygian hosts. Euzetrema knoepffleri Combes, 1965 (Monogenea: Iagotrematidae), which is specific to the salamander Euproctus montanus Savi, 1838 is among the rare monopisthocotylean parasites infesting tetrapod hosts. We sequenced the complete 18S rRNA gene of this parasite to infer its phylogenetic position within the Monopisthocotylea. Our results provide a new insight for coevolutionary scenarios between monopisthocotyleans and gnathostomatan hosts. Indeed, the basal position of E. knoepffleri within a subgroup of the Monopisthocotylea which comprises two clusters that both include parasites of the Actinopterygii and Chondrichthyes, suggests a very old association between the Iagotrematidae and tetrapods. Furthermore, if we take into account a recent view of Gnathostomata evolution where bony and cartilaginous fishes are regarded as a monophyletic group, it could be argued that the Iagotrematidae arose very early, during the fish–tetrapod transition, as did the Polystomatidae, the only monogenean family of the Polyopisthocotylea that infests sarcopterygian hosts.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 727–734.     

Molecular phylogenetics of Thysanoptera

Analyses of morphological data on the higher-level phylogenetics of Thysanoptera have suggested two alternative hypotheses: (1) sister-taxon status of the monophyletic suborders Terebrantia and Tubulifera. and (2) paraphyly of Terebrantia with respect to Tubulifera. Analyses of nucleotide sequence data from the mitochondrial gene cytochrome oxidase I and the nuclear gene I8S rONA using maximum parsimony. neighbour joining. and maximum likelihood provide strong support for the hypothesis of a sister-taxon relationship between the Terebrantia and Tubulifera. These data resolve this long-standing controversy in thysanopteran phylogenetics and provide a framework for further studies of higher-level relationships in this order.     

A Paedomorphic parasite associated with a neotenic amphibian host: phylogenetic evidence suggests a revised systematic position for Sphyranuridae within anuran and turtle Polystomatoineans

The phylogenetic relationships of the families Polystomatidae and Sphyranuridae (subclass Polystomatoinea) within tetrapod monogenean parasites were investigated using partial 18S rDNA sequences. About 600 nucleotides of 11 species were sequenced, including 7 species of the most common subfamilies of Polystomatidae found in anurans and turtles, 1 species of the family Sphyranuridae parasitizing exclusively urodelans, and 3 species of the subclass Oligonchoinea infesting teleostean fishes. The phylogenetic analyses were performed using three reconstruction methods: neighbor-joining, maximum-parsimony, and maximum-likelihood. Polystomatoineans but not polystomatids were shown to be monophyletic. Within the polystomatoineans there are two clades: one includes the amphibian monogeneans (anuran polystomatids and urodelan sphyranurids) and the other includes the turtle polystomatids. Polystomatoineans may have coevolved with amphibian hosts, and an ancestral "polystome" dispersed at least 200 million years ago, either from the basal stem of lissamphibians or from an anuran ancestral stock, to freshwater turtles. Furthermore, the urodelan genus Sphyranura, initially assigned to the family Sphyranuridae on the basis of morphological and ontogenetic evidence, is clearly nested within polystomatids, suggesting that its systematic status must be revised. This supports recent findings which argue that species of the family Sphyranuridae may be paedomorphic parasites exclusively infesting neotenic mudpuppies.     

Phylogenetic relationships within the polyopisthocotylean monogeneans (Platyhelminthes) inferred from partial 28S rDNA sequences

Recent studies based on molecular data (18S rDNA and partial 28S rDNA) and morphology did not resolve a terminal polytomy within the Polyopisthocotylea. Here, we have used sequences from the full domain D2 of the 28S rDNA for 24 species (18 new sequences) with three phylogenetic methods, maximum parsimony, neighbour-joining and maximum likelihood, to infer the relationships among the Polyopisthocotylea. The analysis of the domain D2 of the 28S rDNA has been performed on two data sets. The first one, complete, included the Polystomatidae as the outgroup in order to infer general relationships, and the second one, reduced, excluded the Polystomatidae and the polyopisthocotylean parasites of chondrichthyans, but used the Mazocraeidae as the outgroup in order to resolve the relationships between the terminal groups. The topology found, sustained by high bootstrap and decay index value, is: (outgroup (Chimaericolidae (Mazocraeidae (Gastrocotylinea, other Polyopisthocotylea)))). The polyopisthocotylean parasites of chondrichthyans are the sister-group of the polyopisthocotylean parasites of teleosts. In the latter, the Mazocraeidae, essentially parasites of Clupeidae, have a basal position. The polytomy between Gastrocotylinea, Discocotylinea and Microcotylinea is partially resolved in this study for the first time: the Gastrocotylinea are the sister-group of an unresolved group including the Microcotylinea, Discocotylinea and Plectanocotylidae. Inclusion of the Plectanocotylidae in the suborder Mazocraeinea is rejected. Monophyly of the Microcotylinea and Plectanocotylidae is confirmed, but monophyly of the Discocotylinea is questioned by the exclusion of Diplozoon.     

Phylogeny of West AfricanCaryedon(Coleoptera: Bruchidae): Congruence between Molecular and Morphological Data

Seed beetles belonging to the Old World genusCaryedonfeed in the seeds of various Caesalpinioideae, Mimosoideae, and Combretaceae. In an attempt to resolve broad phylogenetic relationships within the genus, we obtained 332 base pair sequences of mitochondrial 12S ribosomal DNA and morphological data for the 16 West AfricanCaryedonspecies. Morphological characters were analyzed under maximum parsimony and sequences were compared under maximum parsimony, maximum likelihood, and neighbor joining. Using a partition homogeneity test, we determined that morphological and molecular data sets were combinable. Combined data were analyzed under maximum parsimony. Morphological and molecular trees were congruent at the species group level and total evidence analyses yielded the same topologies as molecular data with each of the three outgroups used. Four main terminal clades are recognized, each corresponding with a group of species generally feeding on the same host plant family, subfamily, genus, or species. The monophyly of legume feedingCaryedonis supported by both data sets, and Combretaceae feeders split in two monophyletic assemblages.     

Phylogenetic relationships of Palaeacanthocephala (Acanthocephala) inferred from SSU and LSU rDNA gene sequences

The Palaeacanthocephala is traditionally represented by 2 orders, Echinorhynchida and Polymorphida, with 10 and 3 families, respectively. To test the monophyly of the class, these 2 orders, and certain families, phylogenies were inferred using nuclear small-subunit (SSU) and large-subunit (LSU) ribosomal DNA sequences obtained for 29 species representing 10 families, 2 other classes of acanthocephalans, and 3 rotifer outgroups. Phylogenetic relationships were inferred by analyzing combined SSU and LSU sequences using maximum parsimony (MP) and maximum likelihood (ML) methods. Parsimony and ML trees inferred from combined analysis of these rDNA data strongly supported monophyly of Palaeacanthocephala and provided good resolution among species. Neither Polymorphida nor Echinorhynchida was monophyletic. Gorgorhynchoides bullocki (Echinorhynchida) was nested within the 6 species representing Polymorphida, and this clade was nested within species representing Echinorhynchida. Three of 4 palaeacanthocephalan families that could be evaluated were not monophyletic, and this finding was strongly supported. These results indicate that the family level classification of palaeacanthocephalans, which is mainly based on combinations of shared characters (not shared derived characters), needs to be reevaluated with respect to comprehensively sampled phylogenetic hypotheses.     

A view of early vertebrate evolution inferred from the phylogeny of polystome parasites (Monogenea: Polystomatidae)

The Polystomatidae is the only family within the Monogenea to parasitize sarcopterygians such as the Australian lungfish Neoceratodus poisteri and freshwater tetrapods (lissamphibians and chelonians). We present a phylogeny based on partial 18S rDNA sequences of 26 species of Polystomatidae and three taxon from the infrasubclass Oligonchoinea (= Polyopisthocotylea) obtained from the gills of teleost fishes. The basal position of the polystome from lungfish within the Polystomatidae suggests that the family arose during the evolutionary transition between actinopterygians and sarcopterygians, ca. 425 million years (Myr) ago. The monophyly of the polystomatid lineages from chelonian and lissamphibian hosts, in addition to estimates of the divergence times, indicate that polystomatids from turtles radiated ca. 191 Myr ago, following a switch from an aquatic amniote presumed to be extinct to turtles, which diversified in the Upper Triassic. Within polystomatids from lissamphibians, we observe a polytomy of four lineages, namely caudatan, neobatrachian, pelobatid and pipid polystomatid lineages, which occurred ca. 246 Myr ago according to molecular divergence-time estimates. This suggests that the first polystomatids of amphibians originated during the evolution and diversification of lissamphibian orders and suborders ca. 250 Myr ago. Finally, we report a vicariance event between two major groups of neobatrachian polystomes, which is probably linked to the separation of South America from Africa ca. 100 Myr ago.     

Cytochrome b phylogeny of North American hares and jackrabbits (Lepus, lagomorpha) and the effects of saturation in outgroup taxa

Jackrabbits and hares, members of the genus Lepus, comprise over half of the species within the family Leporidae (Lagomorpha). Despite their ecological importance, potential economic impact, and worldwide distribution, the evolution of hares and jackrabbits has been poorly studied. We provide an initial phylogenetic framework for jackrabbits and hares so that explicit hypotheses about their evolution can be developed and tested. To this end, we have collected DNA sequence data from a 702-bp region of the mitochondrial cytochrome b gene and reconstructed the evolutionary history (via parsimony, neighbor joining, and maximum likelihood) of 11 species of Lepus, focusing on North American taxa. Due to problems of saturation, induced by multiple substitutions, at synonymous coding positions between the ingroup taxa and the outgroups (Oryctolagus and Sylvilagus), both rooted and unrooted trees were examined. Variation in tree topologies generated by different reconstruction methods was observed in analyses including the outgroups, but not in the analyses of unrooted ingroup networks. Apparently, substitutional saturation hindered the analyses when outgroups were considered. The trees based on the cytochrome b data indicate that the taxonomic status of some species needs to be reassessed and that species of Lepus within North America do not form a monophyletic entity.     

Phylogenetic analysis of the Monocotylidae (Monogenea) inferred from 28S rDNA sequences

The current classification of the Monocotylidae (Monogenea) is based on a phylogeny generated from morphological characters. The present study tests the morphological phylogenetic hypothesis using molecular methods. Sequences from domains C2 and D1 and the partial domains C1 and D2 from the 28S rDNA gene for 26 species of monocotylids from six of the seven subfamilies were used. Trees were generated using maximum parsimony, neighbour joining and maximum likelihood algorithms. The maximum parsimony tree, with branches showing less than 70% bootstrap support collapsed, had a topology identical to that obtained using the maximum likelihood analysis. The neighbour joining tree, with branches showing less than 70% support collapsed, differed only in its placement of Heterocotyle capricornensis as the sister group to the Decacotylinae clade. The molecular tree largely supports the subfamilies established using morphological characters. Differences are primarily how the subfamilies are related to each other. The monophyly of the Calicotylinae and Merizocotylinae and their sister group relationship is supported by high bootstrap values in all three methods, but relationships within the Merizocotylinae are unclear. Merizocotyle is paraphyletic and our data suggest that Mycteronastes and Thaumatocotyle, which were synonymized with Merizocotyle after the morphological cladistic analysis, should perhaps be resurrected as valid genera. The monophyly of the Monocotylinae and Decacotylinae is also supported by high bootstrap values. The Decacotylinae, which was considered previously to be the sister group to the Calicotylinae plus Merizocotylinae, is grouped in an unresolved polychotomy with the Monocotylinae and members of the Heterocotylinae. According to our molecular data, the Heterocotylinae is paraphyletic. Molecular data support a sister group relationship between Troglocephalus rhinobatidis and Neoheterocotyle rhinobatidis to the exclusion of the other species of Neoheterocotyle and recognition of Troglocephalus renders Neoheterocotyle paraphyletic. We propose Troglocephalus incertae sedis. An updated classification and full species list of the Monocotylidae is provided.     

Phylogenetic analysis of the Monocotylidae (Monogenea) inferred from 28S rDNA sequences

The current classification of the Monocotylidae (Monogenea) is based on a phylogeny generated from morphological characters. The present study tests the morphological phylogenetic hypothesis using molecular methods. Sequences from domains C2 and D1 and the partial domains C1 and D2 from the 28S rDNA gene for 26 species of monocotylids from six of the seven subfamilies were used. Trees were generated using maximum parsimony, neighbour joining and maximum likelihood algorithms. The maximum parsimony tree, with branches showing less than 70% bootstrap support collapsed, had a topology identical to that obtained using the maximum likelihood analysis. The neighbour joining tree, with branches showing less than 70% support collapsed, differed only in its placement of Heterocotyle capricornensis as the sister group to the Decacotylinae clade. The molecular tree largely supports the subfamilies established using morphological characters. Differences are primarily how the subfamilies are related to each other. The monophyly of the Calicotylinae and Merizocotylinae and their sister group relationship is supported by high bootstrap values in all three methods, but relationships within the Merizocotylinae are unclear. Merizocotyle is paraphyletic and our data suggest that Mycteronastes and Thaumatocotyle, which were synonymized with Merizocotyle after the morphological cladistic analysis, should perhaps be resurrected as valid genera. The monophyly of the Monocotylinae and Decacotylinae is also supported by high bootstrap values. The Decacotylinae, which was considered previously to be the sister group to the Calicotylinae plus Merizocotylinae, is grouped in an unresolved polychotomy with the Monocotylinae and members of the Heterocotylinae. According to our molecular data, the Heterocotylinae is paraphyletic. Molecular data support a sister group relationship between Troglocephalus rhinobatidis and Neoheterocotyle rhinobatidis to the exclusion of the other species of Neoheterocotyle and recognition of Troglocephalus renders Neoheterocotyle paraphyletic. We propose Troglocephalus incertae sedis. An updated classification and full species list of the Monocotylidae is provided.     

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.     

A phylogeny of Drosophilidae using the Amyrel gene: questioning the Drosophila melanogaster species group boundaries

In this study, the phylogenetic relationships of 164 species of the family Drosophilidae are discussed, using the Amyrel gene, a member of the α -amylase multigene family. This study focuses on numerous species groups in the subgenera Sophophora and Drosophila of the genus Drosophila but also includes other closely related genera. Nucleotide data were analysed by several methods: maximum parsimony, neighbour joining, maximum likelihood and Bayesian inference. Heterogeneity of base composition (mainly low GC contents in the species groups willistoni and saltans ) has been addressed. In all analyses, the genus Drosophila appeared paraphyletic. The subgenus Sophophora clearly appeared to be a monophyletic group, showing well-resolved clades, with the Neotropical groups arising in a basal position. Here, it is proposed to raise the species subgroups ananassae and montium to the rank of species group, and to restrict the melanogaster species group to the melanogaster subgroup plus the 'Oriental' subgroups, among which the suzukii subgroup is polyphyletic. Some related genera such as Zaprionus , Liodrosophila , Scaptomyza and Hirtodrosophila are clustered with, or inside the subgenus Drosophila , which is therefore paraphyletic and should be reviewed.     

False Vertical Rootlets of Epidermal Cilia in the Oncomiracidia of Neoheterocotyle rhinobatidis and Monocotyle spiremae (Platyhelminthes,Monogenea, Monopisthocotylea)

Epidermal cilia of the oncomiracidium of Neoheterocotyle rhinobatidis (Monogenea, Monopisthocotylea, Monocotylidae) have long cross-striated vertical rootlets that are not extensions of the basal bodies as are the vertical rootlets in all catenulid and rhabditophoran turbellarians examined to date. Instead, they originate in the basal part of the horizontal rootlet a short distance from the basal bodies. In Monocotyle spiremae (Monocotylidae), the vertical rootlets are less distinct, with no apparent cross-striation, but they also originate from the basal part of the horizontal rootlets. Epidermal cilia of the oncomiracidium of Zeuxapta seriolae (Monogenea, Polyopisthocotylea, Axinidae) lack vertical rootlets like all other neodermatans examined, but bundles of fibres extend from the basal bodies a short distance into the cytoplasm of the epidermal cells. Monopisthocotylean Monogenea would be intermediate between rhabditophorans and the other neodermatans (in having weakly developed vertical rootles), if these structures were homologous in the two groups. However, in view of the different origin of vertical rootlets in turbellarians and monopisthocolylean oncomiracidia, it is suggested that they are not homologous, and vertical rootlets in the Monopisthocotylea are therefore named “false vertical rootlets”.     

Morphology agrees with molecular data: phylogenetic affinities of Euptychiina butterflies (Nymphalidae: Satyrinae)

Euptychiina is the most species‐rich subtribe of Neotropical Satyrinae, with over 450 known species in 47 genera (14 monotypic). Here, we use morphological characters to examine the phylogenetic relationships within Euptychiina. Taxonomic sampling included 105 species representing the majority of the genera, as well as five outgroups. A total of 103 characters were obtained: 45 from wing pattern, 48 from genitalia and 10 from wing venation. The data matrix was analysed using maximum parsimony under both equal and extended implied weights. Euptychiina was recovered as monophyletic with ten monophyletic genera, contrasting previous DNA sequence‐based phylogenies that did not recover the monophyly of the group. In agreement with sequence‐based hypotheses, however, three main clades were recognized: the ‘Megisto clade’ with six monophyletic and three polyphyletic genera, the ‘Taygetis clade’ with nine genera of which three were monophyletic, and the ‘Pareuptyhia clade’ with four monophyletic and two polyphyletic genera. This is the first morphology‐based phylogenetic hypothesis for Euptychiina and the results will be used to complement molecular data in a combined analysis and to provide critical synapomorphies for clades and genera in this taxonomically confused group.     

Sponge paraphyly and the origin of Metazoa

In order to allow critical evaluation of the interrelationships between the three sponge classes, and to resolve the question of mono‐ or paraphyly of sponges (Porifera), we used the polymerase chain reaction (PCR) to amplify almost the entire nucleic acid sequence of the 18S rDNA from several hexactinellid, demosponge and calcareous sponge species. The amplification products were cloned, sequenced and then aligned with previously reported sequences from other sponges and nonsponge metazoans and variously distant outgroups, and trees were constructed using both neighbour‐joining and maximum parsimony methods. Our results suggest that sponges are paraphyletic, the Calcarea being more related to monophyletic Eumetazoa than to the siliceous sponges (Demospongiae, Hexactinellida). These results have important implications for our understanding of metazoan origins, because they suggest that the common ancestor of Metazoa was a sponge. They also have consequences for basal metazoan classification, implying that the phylum Porifera should be abandoned. Our results support the upgrading of the calcareous sponge class to the phylum level.     

基于线粒体ND1和COI基因序列探讨锯眼蝶亚科主要类群的系统发生关系

测定了分布于中国的锯眼蝶亚科4族10属共20个种的线粒体ND1和COI基因的部分序列,结合从GenBank中获得的4个国外种类的同源序列,以凤蝶科的迪洛尔娟凤蝶(Allancatria deyrolle)、丝带凤蝶(Sericinus montela),以及娟蝶科的西猛娟蝶(Parnassius simonius)为外类群,通过邻接法、最大简约法、最大似然法和贝叶斯法重建了分子系统树,分析了该亚科内主要类群的系统发生关系。分析结果表明:帻眼蝶族和锯眼蝶族具有较近的亲缘关系;黛眼蝶族不是单系群,该族中的黛眼蝶属、荫眼蝶属与眉眼蝶族具有较近的亲缘关系,带眼蝶属、藏眼蝶属、毛眼蝶属和帕眼蝶属聚合为一个独立的支系,其中带眼蝶属和藏眼蝶属在所有的分析方法中均以100%的置信度(BP=100%,PP=1.00)相聚合,建议将它们合并为一属。     

基于线粒体ND1和CO1基因序列探讨锯眼蝶-亚科主要类群的系统发生关系

研究测定了锯眼蝶亚科4族、10属共20个国产代表种的线粒体ND1和COI基因的部分序列,结合从GenBank中获得的4个国外产种类的同源序列,以凤蝶科的迪洛尔娟凤蝶、丝带凤蝶,以及娟蝶科的西猛娟蝶为外类群,通过邻接法、最大简约法、最大似然法和贝叶斯法重建了分子系统树,分析了该亚科及其主要类群的系统发生关系。分析结果表明：帻眼蝶族和锯眼蝶族具有较近的亲缘关系;黛眼蝶族不是单系群,该族中的黛眼蝶属、荫眼蝶属与眉眼蝶族具有较近的亲缘关系,带眼蝶属、藏眼蝶属、毛眼蝶属和帕眼蝶属聚合为一个独立的支系,其中带眼蝶属和藏眼蝶属在所有的分析方法中均以100%的置信度（BP=100%, PP=1.00）相聚合,笔者倾向于将它们合并为一属。     

Phylogeny of Camellia sects Longipedicellata,Chrysantha and Longissima (Theaceae) Based on Sequence Data of Four Chloroplast DNA Loci

We focused on the systematic positions and relationships of three sections of Camellia subgenThea of Theaceae, i.e., sect.Longipedicellata, sect.Chrysantha (golden camellias) and sect.Longissima by using four chloroplast DNA regions (rpl16, psbA trnH, trnL F & rpl32 trnL). We sampled 28 species representing four subgenus, 11 sections in Camellia and two outgroups. Combined analyses of chloroplast DNA sequence data sets are performed with the neighbor joining, maximum parsimony and Bayesian inference methods, and the gene trees are constructed. The topologies of gene trees revealed that: 1) sect. Chrysantha is paraphyletic or polyphyletic, containing three parallel lineages and Camellia longipedicellata (type of sectLongipedicellata) nested inside; 2) all four species from Vietnam, together with C. longipedicellata, forming a well supported monophyletic clade, which implies the close relationship between sect. Longipedicellata and sect.Chrysantha; and 3) sectLongissima is not monophyletic because C.hekouensis is the sister to the rest of Camellia species. The systematic position of C.longissima and the relationship between sect.Longissima and sect.Longipedicellata are unsolved.     

基于叶绿体四个DNA 片段联合分析探讨山茶属长柄山茶组、金花茶组和超长柄茶组的系统位置与亲缘关系

为探讨山茶属茶亚属 (Camellia subgenThea) 中长柄山茶组 (sectLongipedicellata)、金花茶组 (sectChrysantha)和超长柄茶组 (sectLongissima) 的系统位置和亲缘关系,本研究选取了该属4个亚属11组28个种及2个外类群的材料,对这些材料的叶绿体4个DNA片段 (rpl16、psbA trnH、trnL F和rpl32 trnL) 进行了测序,运用邻接法 (neighbor joining)、最大简约法 (maximum parsimony) 和贝叶斯推断 (Bayesian inference) 对获得的序列进行了联合矩阵分析,并构建基因树。基因树的拓扑结构显示：1) 金花茶组包括3个平行的支系,并且长柄山茶组的模式种长柄山茶 (Camellia longipedicellata) 嵌于其中一个支系,因而金花茶组可能是一个并系或多系类群;2) 长柄山茶与越南分布的金花茶组种类在分子系统树上构成一个单系支,暗示了长柄山茶组和金花茶组之间可能具有紧密的亲缘关系;3) 超长柄茶组不是一个单系类群,该组的河口超长柄茶 (C. hekouensis) 位于系统树的基部,与山茶属其余种构成姐妹群。由于缺乏更广泛取样的分析,超长柄茶在山茶属中的系统位置仍然不明确,超长柄茶组与长柄山茶组的亲缘关系问题也没有得到解决。     

Mitochondrial DNA sequences of six sturgeon species and phylogenetic relationships within Acipenseridae

Studies on mitochondrial DNA variability amongst six sturgeon species reared in Italian aquaculture plants are reported. Restriction analysis by Rsal of mitochondrial cytochrome b and D-loop fragments amplified by PCR permitted identification of interspecific variations that would be suitable as markers for species diagnosis. Data obtained by partial sequencing of the cytochrome b gene, analyzed through maximum parsimony, neighbour joining, and UPGMA distance methods, revealed species clusters that support previous morpho-meristic and geographical data for sturgeon classification into sub-genera. According to our cluster analysis, the genera Acipenser and Huso are monophyletic. Moreover, these and previous cytogenetic data suggest that three 120-chromosome species (H. huso, H. dauricus and A. ruthenus) are at the base of sturgeon differentiation, which occurred through two different events of polyploidization.