Molecular phylogeny of onygenalean fungi based on small subunit ribosomal DNA (SSU rDNA) sequences

Phylogenetic analysis of nucleotide data from small subunit ribosomal DNA (SSU rDNA) sequences (ca. 1685 bp.) was performed on 19 taxa of the Onygenales and three related mitosporic fungi. Phylogenetic trees were constructed by the neighbor-joining method with the sequence data of related taxa obtained from DNA databases. The species in the Onygenales form two clusters and seven subclusters, and the tree topology reflects the traditional classification by Currah (1985) with some exceptions. The Myxotrichaceae is placed in the different lineage, separate from other plectomycetous taxa and among the Leotiales and the Erysiphales. Furthermore, two separate lineages in the Myxotrichaceae were found. Tree topology suggested the Onygenaceae is polyphyletic and composed of three subgroups; 1) most members of Onygenaceae, 2)Spiromastix warcupii, and 3) pathogenic dimorphic fungi classified inAjellomyces.     

SSU rDNA phylogeny of cladoniiform lichens

To examine phylogenetic relationships among the "cladoniiform" lichenized fungi, i.e., the families Cladoniaceae, Baeomycetaceae, Icmadophilaceae, Stereocaulaceae, and Siphulaceae, and to provide evidence for the anticipated independent origins of podetia and pseudopodetia, we conducted phylogenetic analyses of SSU (small subunit) rDNA sequences from 39 lichen-forming fungi. These fungi represent all of the major growth forms of lichen associations, fruticose (including "cladoniiform"), foliose, and crustose. Our analysis suggests that lichen-forming fungi with a "cladoniiform" morphology arose multiple times within the ascomycetes. Additionally, each of the other thallus growth forms, crustose, foliose, and fruticose, have originated multiple times. It also seems to be clear that neither all podetiate nor all pseudopodetiate taxa form a monophyletic group. Therefore the term "podetium" should be restricted to homologous structures that are most probably limited to the genera Cladonia, Cladina, Pycnothelia, and allies. The "pseudopodetia" of Stereocaulon (Stereocaulaceae) and Cladia (Cladiaceae) may represent different states of the same homologous character. Our phylogenetic hypothesis supports the monophyletic origin of the order Lecanorales sensu stricto, including representatives of five suborders Cladoniineae, Lecanorineae, Teloschistineae, Agyriineae and Peltigerineae, but excluding representatives of the suborders Acarosporineae (Acarospora schleicheri and Megaspora verrucosa), Pertusariineae (Pertusaria trachythallina), and Umbilicarineae. The suborder Cladoniineae and the family Cladoniaceae both appear to be polyphyletic assemblages.     

Molecular data and phylogeny of Nosema infecting lepidopteran forest defoliators in the genera Choristoneura and Malacosoma

ABSTRACT. Nosema isolates from five lepidopteran forest defoliators, Nosema fumiferanae from spruce budworm, Choristoneura fumiferana ; a Nosema sp. from jack pine budworm, Choristoneura pinus pinus and western spruce budworm, Choristoneura occidentalis ( Nosema sp. CPP and Nosema sp. CO, respectively); Nosema thomsoni from large aspen tortrix, Choristoneura conflictana ; and Nosema disstriae , from the forest tent caterpillar, Malacosoma disstria were compared based on their small subunit (SSU) ribosomal RNA (rRNA) gene sequences. Four of the species sequenced, N. fumiferanae , Nosema sp. CPP, Nosema sp. CO, and N . disstriae have a high SSU rDNA sequence identity (0.6%–1.5%) and are members of the "true Nosema " clade. They all showed the reverse arrangement of the (large subunit [LSU]–internal transcribed spacer [ITS]–SSU) of the rRNA gene. The fifth species, N. thomsoni has the usual (SSU–ITS–LSU) arrangement and is not a member of this clade showing only an 82% sequence similarity. We speculate, therefore, that a genetic reversal may have occurred in the common ancestor to the "true Nosema " clade. Although, the mechanism for rearrangement of the rRNA gene subunits is not known we provide a possible explanation for the localization. N. fumiferanae , Nosema sp. CPP, and Nosema sp. CO clustered together on the inferred phylogenetic tree. The high sequence similarities, the reverse arrangement in the rRNA gene subunits, and the phylogenetic clustering suggest that these three species are closely related but separate species.     

Bayesian inference of cetacean phylogeny based on mitochondrial genomes

The phylogeny of Cetacea (whales, dolphins, porpoises) has long attracted the interests of biologists and has been investigated by many researchers based on different datasets. However, some phylogenetic relationships within Cetacea still remain controversial. In this study, Bayesian analyses were performed to infer the phylogeny of 25 representative species within Cetacea based on their mitochondrial genomes for the first time. The analyses recovered the clades resolved by the previous studies and strongly supported most of the current cetacean classifications, such as the monophyly of Odontoceti (toothed whales) and Mysticeti (baleen whales). The analyses provided a reliable and comprehensive phylogeny of Cetacea which can provide a foundation for further exploration of cetacean ecology, conservation and biology. The results also showed that: (i) the mitochondrial genomes were very informative for inferring phylogeny of Cetacea; and (ii) the Bayesian analyses outperformed other phylogenetic methods on inferring mitochondrial genome-based phylogeny of Cetacea.     

Molecular phylogeny of parasitic Platyhelminthes based on sequences of partial 28S rDNA D1 and mitochondrial cytochrome c oxidase subunit I

The phylogenic relationships existing among 14 parasitic Platyhelminthes in the Republic of Korea were investigated via the use of the partial 28S ribosomal DNA (rDNA) D1 region and the partial mitochondrial cytochrome c oxidase subunit 1 (mCOI) DNA sequences. The nucleotide sequences were analyzed by length, G + C %, nucleotide differences and gaps in order to determine the analyzed phylogenic relationships. The phylogenic patterns of the 28S rDNA D1 and mCOI regions were closely related within the same class and order as analyzed by the PAUP 4.0 program, with the exception of a few species. These findings indicate that the 28S rDNA gene sequence is more highly conserved than are the mCOI gene sequences. The 28S rDNA gene may prove useful in studies of the systematics and population genetic structures of parasitic Platyhelminthes.     

The evolution of the diatoms (Bacillariophyta). I. Origin of the group and assessment of the monophyly of its major divisions

The diatoms are one of the best characterised algal groups. Despite this, little is known of the evolution of the group from the earliest cell to the myriad of taxa known today. Relationships among taxa at the family or generic level have been recognised in some diatoms. However, relationships at higher taxonomic levels are poorly understood and have often been strongly influenced by the first appearances of key taxa in the fossil record. An independent assessment of relationships among the diatoms at these higher taxonomic levels has been made using rRNA sequence data to infer phylogenetic relationships. In this paper we present an analysis of 18S rRNA data from several chosen centric, araphid and raphid pennate taxa. The phylogenetic inferences from these 18S rRNA sequences are supported by evidence from the fossil record and evidence from ontogenetic data. Ribosomal RNA data indicate that both the centric and araphid pennate lineages may not be monophyletic.     

Divergent Histories of rDNA Group I Introns in the Lichen Family Physciaceae

The wide but sporadic distribution of group I introns in protists, plants, and fungi, as well as in eubacteria, likely resulted from extensive lateral transfer followed by differential loss. The extent of horizontal transfer of group I introns can potentially be determined by examining closely related species or genera. We used a phylogenetic approach with a large data set (including 62 novel large subunit [LSU] rRNA group I introns) to study intron movement within the monophyletic lichen family Physciaceae. Our results show five cases of horizontal transfer into homologous sites between species but do not support transposition into ectopic sites. This is in contrast to previous work with Physciaceae small subunit (SSU) rDNA group I introns where strong support was found for multiple ectopic transpositions. This difference in the apparent number of ectopic intron movements between SSU and LSU rDNA genes may in part be explained by a larger number of positions in the SSU rRNA, which can support the insertion and/or retention of group I introns. In contrast, we suggest that the LSU rRNA may have fewer acceptable positions and therefore intron spread is limited in this gene. Reviewing Editor: Dr. W. Ford Doolittle     

Molecular phylogeny of the Korean Rivellia species (Diptera: Tephritoidea: Platystomatidae) based on 16S rDNA sequences: Testing morphological hypotheses using molecular data

The phylogeny of the genus Rivellia Robineau‐Desvoidy was inferred from mitochondrial 16S ribosomal (r)DNA gene sequences of 13 Korean Rivellia species and six species representing other platystomatid genera and the family Tephritidae. We compared the inferred molecular phylogeny with the previously published morphological cladogram. As a result, the following phylogenetic relationships were recognized: (i) monophyly of the genus Rivellia; (ii) monophyly of the R. syngenesiae species group; (iii) R. depicta and R. apicalis (which were not previously placed in any species group) were recognized as a sister group of the R. syngenesiae species group; and (iv) monophyly of the R. basilaris species group was recognized to a limited extent. These results, even though geographically limited, provide a new insight into the phylogeny of the genus Rivellia. They clearly show the utility of 16S rDNA for phylogenetic analysis of the genus Rivellia. Additional study involving samples from different geographical areas will be needed to gain a better understanding of the adaptive radiation of this species‐rich genus.     

Reconstructing the phylogeny of the Sipuncula

Sipunculans are marine spiralian worms with possible close affinities to the Mollusca or Annelida. Currently 147 species, 17 genera, 6 families, 4 orders and 2 classes are recognized. In this paper we review sipunculan morphology, anatomy, paleontological data and historical affiliations. We have conducted cladistic analyses for two data sets to elucidate the phylogenetic relationships among sipunculan species. We first analyzed the relationships among the 45 species of Phascolosomatidea with representatives of the Sipunculidea as outgroups, using 35 morphological characters. The resulting consensus tree has low resolution and branch support is low for most branches. The second analysis was based on DNA sequence data from two nuclear ribosomal genes (18S rRNA and 28S rRNA) and one nuclear protein-coding gene, histone H3. Outgroups were chosen among representative spiralians. In a third analysis, the molecular data were combined with the morphological data. Data were analyzed using parsimony as the optimality criterion and branch support evaluated with jackknifing and Bremer support values. Branch support for outgroup relationships is low but the monophyly of the Sipuncula is well supported. Within Sipuncula, the monophyly of the two major groups, Phascolosomatidea and Sipunculidea is not confirmed. Of the currently recognized families, only Themistidae appears monophyletic. The Aspidosiphonidae, Phascolosomatidae and Golfingiidae would be monophyletic with some adjustments in their definition. The Sipunculidae is clearly polyphyletic, with Sipunculus nudus as the sister group to the remaining Sipuncula, Siphonosoma cumanense the sister group to a clade containing Siphonosoma vastumand the Phascolosomatidea, and Phascolopsis gouldi grouping within the Golfingiiformes, as suggested previously by some authors. Of the genera with multiple representatives, only Phascolosoma and Themiste are monophyletic as currently defined. We are aiming to expand our current dataset with more species in our molecular database and more detailed morphological studies.     

Molecular phylogeny of the Pooideae (Poaceae) based on nuclear rDNA (ITS) sequences

Phylogenetic relationships of the Poaceae subfamily, Pooideae, were estimated from the sequences of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA. The entire ITS region of 25 species belonging to 19 genera representing seven tribes was directly sequenced from polymerase chain reaction (PCR)-amplified DNA fragments. The published sequence of rice, Oryza saliva, was used as the outgroup. Sequences of these taxa were analyzed with maximum parsimony (PAUP) and the neighbor-joining distance method (NJ). Among the tribes, the Stipeae, Meliceae and Brachypodieae, all with small chromosomes and a basic number more than x=7, diverged in succession. The Poeae, Aveneae, Bromeae and Triticeae, with large chromosomes and a basic number of x=7, form a monophyletic clade. The Poeae and Aveneae are the sister group of the Bromeae and Triticeae. On the ITS tree, the Brachypodieae is distantly related to the Triticeae and Bromeae, which differs from the phylogenies based on restriction-site variation of cpDNA and morphological characters. The phylogenetic relationships of the seven pooid tribes inferred from the ITS sequences are highly concordant with the cytogenetic evidence that the reduction in chromosome number and the increase in chromosome size evolved only once in the pooids and pre-dated the divergence of the Poeae, Aveneae, Bromeae and Triticeae.This paper reports factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitableThis paper is a cooperative investigation of USDA-ARS and the Utah Agricultural Experiment Station. Logan, Utah 84322. Journal Paper No. 4581     

Bayesian phylogeny analysis via stochastic approximation Monte Carlo

Monte Carlo methods have received much attention in the recent literature of phylogeny analysis. However, the conventional Markov chain Monte Carlo algorithms, such as the Metropolis–Hastings algorithm, tend to get trapped in a local mode in simulating from the posterior distribution of phylogenetic trees, rendering the inference ineffective. In this paper, we apply an advanced Monte Carlo algorithm, the stochastic approximation Monte Carlo algorithm, to Bayesian phylogeny analysis. Our method is compared with two popular Bayesian phylogeny software, BAMBE and MrBayes, on simulated and real datasets. The numerical results indicate that our method outperforms BAMBE and MrBayes. Among the three methods, SAMC produces the consensus trees which have the highest similarity to the true trees, and the model parameter estimates which have the smallest mean square errors, but costs the least CPU time.     

A comparison of 18s ribosomal RNA and rubisco large subunit sequences for studying angiosperm phylogeny

Summary Partial sequences of 18s rRNA were obtained for 2 gymnosperms and 12 angiosperms from a wide range of families and these were analyzed with 5 other published sequences to form a phylogenetic tree. Using 16 published sequences of the large subunit of rubisco (rbcL), also from a wide range of angiosperm families, another phylogenetic tree was derived and the two approaches were compared. Both phylogenetic trees gave good grouping within families but in neither case was there resolution of the branching order of major taxa. Superficially the long rbcL sequences (whose base composition was homogeneous among all species) seemed very promising, but analysis showed that a large proportion of the variation did not affect the amino acid sequence. Although silent substitution contained some phylogenetic information, at the level required to order major taxa, much of it was random and obfuscating. It was concluded that neither macromolecule alone was likely to yield a solution to the problem of angiosperm phylogeny and therefore that studies of both, at least, will be required. For this reason, a method wa described for obtaining both DNA and RNA of good quality from the same preparation and which had been used successfully with a wide range of species including many with pungent leaves.     

Phylogenetic analysis of Nosema antheraeae (Microsporidia) isolated from Chinese oak silkworm, Antheraea pernyi

The microsporidian Nosema antheraeae is a pathogen that infects the Chinese oak silkworm, Antheraea pernyi. We sequenced the complete small subunit (SSU) rRNA gene and the internal transcribed spacer (ITS) of N. antheraeae, and compared the SSU rRNA sequences in other microsporidia. The results indicated that Nosema species, including N. antheraeae, formed two distinct clades, consistent with previous observations. Furthermore, N. antheraeae is clustered with N. bombycis with high bootstrap support. The organization of the rRNA gene of N. antheraeae is LSU-ITS1-SSU-ITS2-5S, also following a pattern similar to the Nosema type species, N. bombycis. Thus, N. antheraeae is a Nosema species and has a close relationship to N. bombycis.     

Molecular phylogeny of leeches: Congruence of nuclear and mitochondrial rDNA data sets and the origin of bloodsucking

Complete 18S rDNA sequences and sequences of domain III of mitochondrial 12S rDNA were obtained to assess phylogenetic relationships among major suprageneric taxa of leeches and the possibly closely related clitellate taxa Branchiobdellida and Acanthobdellida. The monophyly of the families Erpobdellidae, Piscicolidae, and Glossiphoniidae, the suborders Erpobdelliformes and Hirudiniformes, and the order Arhynchobdellida have been confirmed by parsimony and maximum likelihood phylogenetic analysis of separate and combined data sets. Both the nuclear 18S rDNA sequences and the mitochondrial 12S rDNA sequences were consistent in not supporting a monophyletic order Rhynchobdellida, represented by the families Piscicolidae and Glossiphoniidae. A topology with the Piscicolidae as the first branch in the leech tree followed by the Glossiphoniidae received the highest support in terms of taxonomic, character, and outgroup congruence. According to this topology, the putative apomorphies of the Rhynchobdellidae (e.g. the proboscis) can be parsimoniously explained as plesiomorphies already present in the ancestral leech. This common ancestor was probably a bloodsucking leech with a proboscis rather than an unspecialized ectocommensal, as suggested by previous hypotheses. During the course of leech evolution, a reduction of the proboscis could have taken place in predatory arhynchobdellid ancestors to enable swallowing of larger prey. A second gain of sanguivory by the jawed Hirudiniformes could have been facilitated by pre-adaptations to ectoparasitic blood feeding. The 18S rDNA analysis further indicates a close relationship between the clitellate groups Branchiobdellida and Acanthobdellida, although this relationship is not strongly supported.     

Combined heat shock protein 90 and ribosomal RNA sequence phylogeny supports multiple replacements of dinoflagellate plastids

Dinoflagellates harbour diverse plastids obtained from several algal groups, including haptophytes, diatoms, cryptophytes, and prasinophytes. Their major plastid type with the accessory pigment peridinin is found in the vast majority of photosynthetic species. Some species of dinoflagellates have other aberrantly pigmented plastids. We sequenced the nuclear small subunit (SSU) ribosomal RNA (rRNA) gene of the "green" dinoflagellate Gymnodinium chlorophorum and show that it is sister to Lepidodinium viride, indicating that their common ancestor obtained the prasinophyte (or other green alga) plastid in one event. As the placement of dinoflagellate species that acquired green algal or haptophyte plastids is unclear from small and large subunit (LSU) rRNA trees, we tested the usefulness of the heat shock protein (Hsp) 90 gene for dinoflagellate phylogeny by sequencing it from four species with aberrant plastids (G. chlorophorum, Karlodinium micrum, Karenia brevis, and Karenia mikimotoi) plus Alexandrium tamarense, and constructing phylogenetic trees for Hsp90 and rRNAs, separately and together. Analyses of the Hsp90 and concatenated data suggest an ancestral origin of the peridinin-containing plastid, and two independent replacements of the peridinin plastid soon after the early radiation of the dinoflagellates. Thus, the Hsp90 gene seems to be a promising phylogenetic marker for dinoflagellate phylogeny.     

基于28SrDNA序列构建侧耳属系统发育树

通过对侧耳属18个分类单元的28S rDNA序列进行分析,构建了侧耳属较为完整的系统发育树。分子系统学资料显示:Coremiopleurotus组和侧耳属内单、二系菌丝系统分别为多系起源的;Pleurotus组单系菌丝种类、被划分在Tuberregium组的具核侧耳和Lentodiellum组的P. levis能够分别与侧耳属内其他成员进行区分;红侧耳、P. calyptratus、P. opuntiae三者关系密切,而金顶侧耳应作为白黄侧耳的种下分类单元。     

Insights into the phylogeny of systematically controversial haptorian ciliates (Ciliophora, Litostomatea) based on multigene analyses

The ciliate subclass Haptoria is a diverse taxon that includes most of the free-living predators in the class Litostomatea. Phylogenetic study of this group was initially conducted using a single molecular marker small-subunit ribosomal RNA (SSU rRNA genes). Multi-gene analysis has been limited because very few other sequences were available. We performed phylogenetic analyses of Haptoria incorporating new SSU rRNA gene sequences from several debated members of the taxon, in particular, the first molecular data from Cyclotrichium. We also provided nine large-subunit ribosomal RNA (LSU rRNA) gene sequences and 10 alpha-tubulin sequences from diverse haptorians, and two possible relatives of controversial haptorians (Plagiopylea, Prostomatea). Phylogenies inferred from the different molecules showed the following: (i) Cyclotrichium and Paraspathidium were clearly separated from the haptorids and even from class Litostomatea, rejecting their high-level taxonomic assignments based on morphology. Both genera branch instead with the classes Plagiopylea, Prostomatea and Oligohymenophora. This raises the possibility that the well-known but phylogenetically problematic cyclotrichiids Mesodinium and Myrionecta may also have affinities here, rather than with litostomes; (ii) the transfer of Trachelotractus to Litostomatea is supported, especially by the analyses of SSU rRNA and LSU rRNA genes, however, Trachelotractus and Chaenea (more uncertainly) generally form the two deepest lineages within litostomes; and (iii) phylogenies of the new molecular markers are consistent with SSU rRNA gene information in recovering order Pleurostomatida as monophyletic. However, Pleurostomatida branches cladistically within order Haptorida, as does subclass Trichostomatia (on the basis of SSU rRNA phylogenies). Our results suggest that the class-level taxonomy of ciliates is still not resolved, and also that a systematic revision of litostomes is required, beginning at high taxonomic levels (taxa currently ranked as subclasses and orders).