Phylogenetic relationships of the Magnoliaceae inferred from cpDNA matK sequences

The coding region of the matK gene was sequenced to infer the phylogeny of the family Magnoliaceae. Phylogenetic analyses of 21 matK sequences representing ten genera of Magnoliaceae and three outgroups suggest relationships among both subfamilies and genera. Monophyly of the subfamily Liriodendroideae (the genus Liriodendron) and the subfamily Magnolioideae is strongly supported, respectively. Within the subfamily Magnolioideae, three clades are formed: (1) the genus Magnlietia, (2) the subgenus Magnolia, and (3) the subgenus Yulania, with the genera Michelia, Paramichelia, Tsoongiodendron, Alcimandra, Kmeria, Parakmeria and Manglietiastrum. However, the genus Magnolia is shown to be a polyphyletic group, and the genus Michelia a paraphyletic group. Relatively low sequence divergences are detected among genera of the the subfamily Magnolioideae, ranging from 0.14% to 1.70%, especially in the tribe Micheliinae (0.14–0.98%). Molecular evidence from matK sequence data suggests that the phylogenetic positions and the delimitation of the eight genera Magnolia, Michelia, Tsoongiodendron, Paramichelia, Alcimandra, Kmeria, Parakmeria and Manglietiastrum need to be reconsidered. Received: 2 January 2000 / Accepted: 12 February 2000     

Phylogenetic relationships in family Magnoliaceae inferred from ndhF sequences

The ndhF sequences of 99 taxa, representing all sections in extant Magnoliaceae, were analyzed to address phylogenetic questions in the family. Magnolia macrophylla and M. dealbata, North American species of Magnolia section Rytidospermum, are placed at the base in the subfamily Magnolioideae although its supporting value is low. In the remaining taxa, several distinctive lineages are recognized: (1) Magnolia, the biggest genus in the family, is not monophyletic; (2) Michelia, including section Maingola of Magnolia subgenus Magnolia, is closely related with Elmerrillia and sections Alcimandra and Aromadendron of Magnolia subgenus Magnolia; (3) the associates of Michelia are grouped with Magnolia subgenus Yulania and section Gynopodium of Magnolia subgenus Magnolia; (4) Pachylarnax forms a clade with sections Manglietiastrum and Gynopodium of Magnolia; (5) a well-supported Manglietia clade is recognized; (6) Caribbean species of section Theorhodon of Magnolia subgenus Magnolia, which are section Splendentes sensu Vázquez-Garcia, are closely allied with New World members of Magnolia subgenus Talauma; and (7) section Rytidospermum of Magnolia subgenus Magnolia and subgenus Talauma are polyphyletic. The separated clades in the molecular tree are considerably different from traditional taxonomic dispositions in the family. The molecular data strongly suggest that a taxonomic realignment of infrafamilial delimitations and compositions should be considered.     

Phylogenetic relationships of bryophytes inferred from nuclear-encoded rRNA gene sequences

We investigate phylogenetic relationships among hornworts, liverworts and mosses, and their relationships to other green plant groups, by analysis of nucleotide variation in complete 18s rRNA gene sequences of three green algae, two hornworts, seven liverworts, nine mosses, and six tracheophytes. Parsimony and maximum-likelihood analyses yield a single optimal tree in which the hornworts are resolved as the basal group among land plants, and the liverworts and mosses are sister taxa that together form the sister clade to the tracheophytes. This phylogeny is internally robust as indicated by decay indices and by comparison (using both parsimony and likelihood criteria) to topologies representing five alternative hypotheses of bryophyte relationships. We discuss some possible reasons for differences between the phylogeny inferred from the rRNA data and those inferred from other character sets.     

Phylogenetic relationships of New Zealand Asteraceae inferred from ITS sequences

Forty-five sequences from members of all genera of Asteraceae indigenous to New Zealand and 50 published sequences representing the tribal diversity in the family were analyzed to assess the utility of ITS sequences to resolve phylogenetic relationships. Previous studies using chloroplast DNA sequences and morphology provided support for several clades in the Asteraceae, yet the relationships among some of these were uncertain. The results from ITS analysis were largely consistent with these earlier studies. The New Zealand species are included in at least six clades, most of these corresponding to recognized tribes. Our results have also clarified the tribal affinities of a few anomalous genera. Haastia, previously aligned with the Gnaphalieae or the Astereae, is nested in the Senecioneae. Centipeda, previously included in the Astereae or Anthemideae, emerges near the Heliantheae. The relationships of Abrotanella remain unresolved. Received August 8, 2001 Accepted November 6, 2001     

从细胞色素b基因序列探讨笛鲷属的分子系统发生关系

测定了9种中国南海的笛鲷属鱼类的细胞色素b基因的部分序列,结合来自GenBank中1种分布于菲律宾和9种分布于美国大西洋的笛鲷属鱼类的相应同源序列,用邻接法和最大简约法构建分子系统树。结果显示:红鳍笛鲷(Lutjanuserythropterus)与红笛鲷(L.sanguineus)之间的同源序列碱基差异百分率只有0.32%,支持二者是同种异名的观点;中国南海的笛鲷属鱼类间的平均碱基差异要高于美国大西洋笛鲷属鱼类。在MP和NJ树中,美国大西洋笛鲷表现为亲缘关系较近,来源于中国南海的笛鲷鱼类相对集中在树的基部,分歧较大。这与所研究的笛鲷地理分布和地理隔离基本相一致,同时也说明中国南海笛鲷分化较早并且分歧较大。     

Phylogenetic relationships among eukaryotic kingdoms inferred from ribosomal RNA sequences

Summary Phylogenetic trees among eukaryotic kingdoms were inferred for large- and small-subunit rRNAs by using a maximum-likelihood method developed by Felsenstein. Although Felsenstein's method assumes equal evolutionary rates for transitions and transversions, this is apparently not the case for these data. Therefore, only transversiontype substitutions were taken into account. The molecules used were large-subunit rRNAs fromXenopus laevis (Animalia), rice (Plantae),Saccharomyces cerevisiae (Fungi),Dictyostelium discoideum (Protista), andPhysarum polycephalum (Protista); and small-subunit rRNAs from maize (Plantae),S. cerevisiae, X. laevis, rat (Animalia), andD. discoideum. Only conservative regions of the nucleotide sequences were considered for this study. In the maximum-likelihood trees for both large- and small-subunit rRNAs, Animalia and Fungi were the most closely related eukaryotic kingdoms, and Plantae is the next most closely related kingdom, although other branching orders among Plantae, Animalia, and Fungi were not excluded by this work. These three eukaryotic kingdoms apparently shared a common ancestor after the divergence of the two species of Protista,D. discoideum andP. polycephalum. These two species of Protista do not form a clade, andP. polycephalum diverged first andD. discoideum second from the line leading to the common ancestor of Plantae, Animalia, and Fungi. The sequence data indicate that a drastic change occurred in the nucleotide sequences of rRNAs during the evolutionary separation between prokaryote and eukaryote.     

Phylogenetic relationships ofPolemoniaceae inferred from 18S ribosomal DNA sequences

Cladistic analyses of chloroplast DNA disagree with current classifications by placingPolemoniaceae near sympetalous families with two staminal whorls, includingFouquieriaceae andDiapensiaceae, rather than near sympetalous families with a single staminal whorl, such asHydrophyllaceae andConvolvulaceae. To explore further the affinities ofPolemoniaceae, we sequenced 18S ribosomal DNA for eight genera ofPolemoniaceae and 31 families representing a broadly definedAsteridae. The distribution of variation in these sequences suggest some sites are hypervariable and multiple hits at these sites have obscured much of the hierarchical structure present in the data. Nevertheless, parsimony, least-squares minimum evolution, and maximum likelihood methods all support a monophyleticPolemoniaceae that is placed nearFouquieriaceae, Diapensiaceae and related ericalean families.     

Phylogenetic relationships of the Acanthocephala inferred from 18S ribosomal DNA sequences

Phylogenetic relationships within the Acanthocephala have remained unresolved. Past systematic efforts have focused on creating classifications with little consideration of phylogenetic methods. The Acanthocephala are currently divided into three major taxonomic groups: Archiacanthocephala, Palaeacanthocephala, and Eoacanthocephala. These groups are characterized by structural features in addition to the taxonomy and habitat of hosts parasitized. In this study the phylogenetic relationships of 11 acanthocephalan species are examined with 18S rDNA sequences. Maximum parsimony, minimum evolution, and maximum likelihood methods are used to estimate phylogenetic relationships. Within the context of sampled taxa, all phylogenetic analyses are consistent with monophyly of the major taxonomic groups of the Acanthocephala, suggesting that the current higher order classification is natural. The molecular phylogeny is used to examine patterns of character evolution for various structural and ecological characteristics of the Acanthocephala. Arthropod intermediate host distributions, when mapped on the phylogeny, are consistent with monophyletic groups of acanthocephalans. Vertebrate definitive host distributions among the Acanthocephala display independent radiations into similar hosts. Levels of uncorrected sequence divergence among acanthocephalans are high; however, relative-rate tests indicate significant departure from rate uniformity among acanthocephalans, arthropods, and vertebrates. This precludes comparison of 18S divergence levels to assess the relative age of the Acanthocephala. However, other evidence suggests an ancient origin of the acanthocephalan-arthropod parasitic association.     

Phylogenetic relationships of the Clavelinidae and Pycnoclavellidae (Ascidiacea) inferred from mtDNA data

Abstract. The phylogenetic relationships within the Order Aplousobranchiata (Ascidiacea) are largely unexplored. In this work, we study the phylogenetic status of the genera Clavelina and Pycnoclavella. Traditionally, both genera had been included in the family Clavelinidae, until the new family Pycnoclavellidae was defined, removing the genus Pycnoclavella from Clavelinidae. Not all authors accept the validity of Clavelina and Pycnoclavella as distinct genera, let alone their belonging to different families. In addition, the assignment of species to these genera, as well as to the genus Archidistoma , has been controversial. We analyzed sequences of the mitochondrial gene cytochrome c oxidase subunit I belonging to ten species of Pycnoclavella (including several formerly assigned to Archidistoma and Clavelina ), 11 species of Clavelinidae, and ten species of other aplousobranch genera belonging to seven families, plus two outgroups. Two different tree construction methods (maximum likelihood and Bayesian inference) showed similar results. Pycnoclavella and Clavelina appeared in distinct clades but formed a monophyletic group relative to representatives of the main families of the order Aplousobranchiata. Our phylogenetic results indicate that both genera are valid but should be included within a single family, with the name Clavelinidae having precedence. The monotypic clavelinid genus Nephtheis branches in our trees within the clade of the genus Clavelina. Our results also confirm that some forms assigned to Archidistoma and Clavelina have been misplaced and belong to the genus Pycnoclavella. Pycnoclavella martae n.sp. is described.     

Phylogenetic relationships of elopomorph fishes inferred from mitochondrial ribosomal DNA sequences

The superorder Elopomorpha, a grouping which includes all teleost fishes that possess a specialized leptocephalous larva [true eels (Anguilliformes), gulpers and bobtail snipe eels (Saccopharyngiformes), bonefishes, spiny eels, and halosaurs (Albuliformes, including Notacanthiformes), ladyfishes and tarpons (Elopiformes, including Megalopiformes)] comprises >800 species for which phylogenetic relationships are poorly understood. In the present study, we analyzed mitochondrial DNA sequences in segments of the 12S and 16S rRNA genes in 33 elopomorph taxa encompassing all of the previously proposed orders, and 9 of the 15 currently recognized families of the Anguilliformes, as well as outgroup representatives from the superorders Osteoglossomorpha (nine species) and Clupeomorpha (three species), to develop phylogenetic hypotheses based on distance and parsimony methods. Both methods failed to support the monophyly of the Elopomorpha, casting doubt on the validity of the leptocephalus as an elopomorph synapomorphy. The orders Elopiformes, Albuliformes, and Anguilliformes, however, were resolved as monophyletic assemblages. Parsimony analysis supported the separation of the Anguilliformes into two groups (primitive and advanced) based on the presence of divided versus fused frontal bones. In addition, the molecular data indicated a close affinity of the anguilliform Thalassenchelys coheni (incertae sedis), known only from the leptocephalus, with the family Serrivomeridae. The implications of these data as regards the evolution of the elopomorph assemblage are discussed.     

Phylogenetic relationships among Pneumocystis from Asian macaques inferred from mitochondrial rRNA sequences

The presence of Pneumocystis organisms was detected by nested-PCR at mitochondrial large subunit (mtLSU) rRNA gene in 23 respiratory samples from Asian macaques representing two species: Macaca mulatta and M. fascicularis. A very high level of sequence heterogeneity was detected with 18 original sequence types. Two genetic groups of Pneumocystis could be distinguished from the samples. Within each group, the extent of genetic divergence was low (2.5+/-1.4% in group 1 and 2.3+/-1.7% in group 2). Genetic divergences were systematically higher when macaque-derived sequence types were compared with Pneumocystis mtLSU sequences from other primate species (from 5.3+/-2.7% to 19.3+/-3.0%). The two macaque-derived groups may be considered as distinct Pneumocystis species. Surprisingly, these Pneumocystis species were recovered from both M. mulatta and M. fascicularis suggesting that host-species restriction may not systematically occur in the genus Pneumocystis. Alternatively, these observations question about the species concept in macaques.     

Phylogenetic relationships ofSphaerophoraceae (Ascomycetes) inferred from SSU rDNA sequences

SSU rDNA was sequenced from the lichenized fungiBunodophoron scrobiculatum andLeifidium tenerum (Sphaerophoraceae), andStereocaulon ramulosum andPilophorus acicularis (Stereocaulaceae) and analysed by maximum parsimony with 44 homologous ascomycete sequences in a cladistic study. A small insertion (c. 60 nt.) was found in the sequence ofLeifidium tenerum. Sphaerophoraceae constitutes a strongly supported monophyletic group which groups together withLecanora dispersa and theStereocaulaceae. Together withPorpidia crustulata, this larger group is a sistergroup to thePeltigerineae. This analysis thus supports theLecanorales as monophyletic, includingSphaerophoraceae and thePeltigerineae, but does not provide strong support for this monophyly. The analysis also suggests that the prototunicate ascus in theSphaerophoraceae is a reversion to the plesiomorphic state. Based on morphological, anatomical and chemical reasons,Sphaerophoraceae is proposed to belong to one of the groups presently included in the paraphyletic suborderCladoniineae within theLecanorales.     

Phylogenetic relationships among Syndermata inferred from nuclear and mitochondrial gene sequences

Phylogenetic relationships among Syndermata have been extensively debated, mainly because the sister-group of the Acanthocephala has not yet been clearly identified from analyses of morphological and molecular data. Here we conduct phylogenetic analyses on samples from the 4 classes of Acanthocephala (Archiacanthocephala, Eoacanthocephala, Polyacanthocephala, and Palaeacanthocephala) and the 3 Rotifera classes (Bdelloidea, Monogononta, and Seisonidea). We do so using small-subunit (SSU) and large-subunit (LSU) ribosomal DNA and cytochrome c oxidase subunit 1 (cox 1) sequences. These nuclear and mitochondrial DNA sequences were obtained for 27 acanthocephalans, 9 rotifers, and representatives of 6 phyla that were used as outgroups. Maximum parsimony (MP), maximum likelihood (ML), and Bayesian analyses were conducted on the nuclear rDNA(SSU+LSU) and the combined sequence dataset(SSU+LSU+cox 1 genes). Phylogenetic analyses of the combined rDNA and cox 1 data uniformly provided strong support for a clade including rotifers plus acanthocephalans (Syndermata). Strong support was also found for monophyly of Acanthocephala in analyses of the combined dataset or rDNA sequences alone. Within the Acanthocephala the monophyletic grouping of the representatives of each class was strongly supported. Our results depicted Archiacanthocephala as the sister-group to the remaining acanthocephalans. Analyses of the combined dataset recovered a sister-group relationship between Acanthocephala and Bdelloidea by parsimony, likelihood, and Bayesian methods. Support for this clade was generally strong. Alternative topologies that depicted a different rotifer sister-group of Acanthocephala (or monophyly of Rotifera) were significantly worse. In this paraphyletic assemblage of rotifers, the relative positions of Seisonidea and Monogononta to the clade Bdelloidea+Acanthocephala were inconsistent among trees based on different inference methods. These results indicate that Bdelloidea is the free-living sister-group to acanthocephalans, which should prove key for comparative investigations of the morphological, molecular, and ecological changes accompanying the evolution of parasitism.     

Phylogenetic relationships of the genus Paramecium inferred from small subunit rRNA gene sequences

The genus Paramecium includes species that are well known and very common in freshwater environments. Species of Paramecium are morphologically divided into two distinct groups: the "bursaria" subgroup (foot-shaped) and the "aurelia" subgroup (cigar-shaped). Their placement within the class Oligohymenophorea has been supported by the analysis of the small subunit rRNA gene sequence of P. tetraurelia. To confirm the stability of this placement and to resolve relationships within the genus, small subunit rRNA gene sequences of P. bursaria, P. calkinsi, P. duboscqui, P. jenningsi, P. nephridiatum, P. primaurelia, and P. polycaryum were determined and aligned. Trees constructed using distance-matrix, maximum-likelihood, and maximum-parsimony methods all depicted the genus as a monophyletic group, clustering with the other oligohymenophorean taxa. Within the Paramecium clade, P. bursaria branches basal to the other species, although the remaining species of the morphologically defined "bursaria" subgroup do not group with P. bursaria, nor do they form a monophyletic subgroup. However, the species of the "aurelia" subgroup are closely related and strongly supported as a monophyletic group.     

Phylogenetic relationships and biogeography of the genus Chondrostoma inferred from mitochondrial DNA sequences

A phylogeny of the species of the nase genus Chondrostoma was constructed from a complete mitochondrial cytochrome b gene (1140 bp). Molecular phylogeny was used to revise the current systematics of this group, and to infer a biogeographical model of the Mediterranean area during the Cenozoic period. We confirmed the monophyly of the genus Chondrostoma, and defined seven different lineages within it: Polylepis, Arcasii, Lemmingii, Toxostoma, Nasus, C. genei, and C. soetta. The separation of main lineages within Chondrostoma occurred in the Middle-Upper Miocene, approximately 11 million years ago, while the greatest species radiation took place in the Pliocene close to the time the current drainages system were created. It is unlikely that this genus experienced an extensive dispersal during the Messinian, in the Lago-Mare Phase. Given the level of current knowledge, a biogeographical model constructed on the basis of vicariant events seems more realistic than does a dispersalist model.     

Phylogenetic relationships of neopterygian fishes, inferred from mitochondrial DNA sequences.

To investigate the relationships among the three main groups of extant neopterygian fishes--Amiidae, Lepisosteidae, and Teleostei--we sequenced fragments of three mitochondrial genes from 12 different actinopterygian fishes and translated the nucleotide sequences into amino acid sequences. When all three regions are considered together, Amiidae clusters with Lepisosteidae in the most parsimonious cladograms, but other clades, such as Neopterygii and Teleostei, that are well supported by morphological evidence fail to emerge as monophyletic. When the cytochrome b sequences are analyzed together with previously published sequences for other taxa, the majority-rule consensus tree is consistent with the monophyly of Teleostei and Neopterygii and marginally supports the Amiidae + Lepisosteidae clade. In either analysis, when Neopterygii and Teleostei are constrained to monophyly, all the most-parsimonious cladograms support the Amiidae + Lepisosteidae topology. Where molecules and morphology disagree, provisional morphology-based constraints on the analysis of molecular data offer a practical means of integrating the two types of data.     

Phylogenetic relationships of conifers inferred from partial 28S rRNA gene sequences

The conifers, which traditionally comprise seven families, are the largest and most diverse group of living gymnosperms. Efforts to systematize this diversity without a cladistic phylogenetic framework have often resulted in the segregation of certain genera and/or families from the conifers. In order to understand better the relationships between the families, we performed cladistic analyses using a new data set obtained from 28S rRNA gene sequences. These analyses strongly support the monophyly of conifers including Taxaceae. Within the conifers, the Pinaceae are the first to diverge, being the sister group of the rest of conifers. A recently discovered Australian genus Wollemia is confirmed to be a natural member of the Araucariaceae. The Taxaceae are nested within the conifer clade, being the most closely related to the Cephalotaxaceae. The Taxodiaceae and Cupressaceae together form a monophyletic group. Sciadopitys should be considered as constituting a separate family. These relationships are consistent with previous cladistic analyses of morphological and molecular (18S rRNA, rbcL) data. Furthermore, the well-supported clade linking the Araucariaceae and Podocarpaceae, which has not been previously reported, suggests that the common ancestor of these families, both having the greatest diversity in the Southern Hemisphere, inhabited Gondwanaland.     

Phylogenetic relationships of Chalara and allied species inferred from ribosomal DNA sequences

The phylogenetic relationships of Chalara and allied taxa are studied based on ribosomal DAN sequences. Partial 28S rDNA and 18S rDNA regions from 26 strains were sequenced in this study. These and related sequences from GenBank were analyzed using parsimony and Bayesian analyses. Most of the Chalara species clustered in a strongly supported monophyletic lineage representing Helotiales. However, a few Chalara species appeared closely related to Xylariales. The phylogenetic significance of morphological characters observed in Chalara species are evaluated based on our sequence analyses. Conidial septation, conidial width and conidiophore pigmentation are thought to be indicative in understanding their evolutionary relationships. Sterile setae, which traditionally have been used to delimitate Chaetochalara from Chalara, are phylogenetically insignificant.     

Phylogenetic relationships and convergence of helicosporous fungi inferred from ribosomal DNA sequences

Helicosporous fungi form elegant, coiled, and multicellular mitotic spores (conidia). In this paper, we investigate the phylogenetic relationships among helicosporous fungi in the asexual genera Helicoma, Helicomyces, Helicosporium, Helicodendron, Helicoon, and in the sexual genus Tubeufia (Tubeufiaceae, Dothideomycetes, and Ascomycota). We generated ribosomal small subunit and partial large subunit sequences from 39 fungal cultures. These and related sequences from GenBank were analyzed using parsimony, likelihood, and Bayesian analysis. Results showed that helicosporous species arose convergently from six lineages of fungi in the Ascomycota. The Tubeufiaceae s. str. formed a strongly supported monophyletic lineage comprising most species from Helicoma, Helicomyces, and Helicosporium. However, within the Tubeufiaceae, none of the asexual genera were monophyletic. Traditional generic characters, such as whether conidiophores were conspicuous or reduced, the thickness of the conidial filament, and whether or not conidia were hygroscopic, were more useful for species delimitation than for predicting higher level relationships. In spite of their distinctive, barrel-shaped spores, Helicoon species were polyphyletic and had evolved in different ascomycete orders. Helicodendron appeared to be polyphyletic although most representatives occurred within Leotiomycetes. We speculate that some of the convergent spore forms may represent adaptation to dispersal in aquatic environments.     

Phylogenetic relationships of the Far Eastern Araliaceae inferred from ITS sequences of nuclear rDNA

In eight species of the family Araliaceae, inhabiting the territory of the Russian Far East, the sequences of ITS regions of nuclear rDNA were determined. A comparison of these sequences enabled establishment of phylogenetic relationships between the Far Eastern and other members of the family. It was demonstrated that Aralia sensu populations from Primorye and Sakhalin were genetically different and, hereby, could be classified as interspecific taxa. Aralia continentalis along with A. cordata were attributed to the section Aralia sensu. Oplopanax elaus and O. horridus were found to be very close to each other, possibly being the subspecies of one species or relatively young species. Legitimacy of the isolation of two sections within the genus Eleutherococcus was confirmed.