Shimodaira-Hasegawa Test Research Articles

Performance of Topology Tests under Extreme Selection Bias.

Tree tests like the Kishino-Hasegawa (KH) test and chi-square test suffer a selection bias that tests like the Shimodaira-Hasegawa (SH) test and approximately unbiased test were intended to correct. We investigate tree-testing performance in the presence of severe selection bias. The SH test is found to be very conservative and, surprisingly, its uncorrected analog, the KH test has low Type I error even in the presence of extreme selection bias, leading to a recommendation that the SH test be abandoned. A chi-square test is found to usually behave well and but to require correction in extreme cases. We show how topology testing procedures can be used to get support values for splits and compare the likelihood-based support values to the approximate likelihood ratio test (aLRT) support values. We find that the aLRT support values are reasonable even in settings with severe selection bias that they were not designed for. We also show how they can be used to construct tests of topologies and, in doing so, point out a multiple comparisons issue that should be considered when looking at support values for splits.

Median-Joining Networks and Bayesian Phylogenies Often Do Not Tell the Same Story

Inferring phylogenies among intraspecific individuals often yields unresolved relationships (i.e., polytomies). Consequently, methods that compute distance-based abstract networks, like Median-Joining Networks (MJNs), are thought to be more appropriate tools for reconstructing such relationships than traditional trees. Median-Joining Networks visualize all routes of relationships in the form of cycles, if needed, when traditional approaches cannot resolve them. However, the MJN method is a distance-based phenetic approach that does not involve character transformations and makes no reference to ancestor–descendant relationships. Although philosophical and theoretical arguments challenging the implication that MJNs reflect phylogenetic signal in the traditional sense have been presented elsewhere, an empirical comparison with a character-based approach is needed given the increasing popularity of MJN analysis in evolutionary biology. Here, we use the conservative Approximately Unbiased (AU) test to compare 85 cases of branching patterns of cycle-free MJNs and Bayesian Inference (BI) phylogenies using datasets from 55 empirical studies. By rooting the MJN analyses to provide directionality, we report substantial disagreement between computed MJNs and posterior distributions on BI phylogenies. The branching patterns in MJNs and BI phylogenies show significantly different relationships in 37.6% of cases. Among the relationships that do not significantly differ, 96.2% show alternative sets of relationships. Our results indicate that the two methods provide different measures of relatedness in a phylogenetic sense. Finally, our analyses also support previous observations of the statistical hypothesis testing by reconfirming the over-conservativeness of the Shimodaira-Hasegawa test versus the AU test.

Phylogenomic analyses recover a clade of large-bodied decapodiform cephalopods

Phylogenetic relationships among the squids and cuttlefishes (Cephalopoda:Decapodiformes) have resisted clarification for decades, despite multiple analyses of morphological, molecular and combined data sets. More recently, analyses of complete mitochondrial genomes and hundreds of nuclear loci have yielded similarly ambiguous results. In this study, we re-evaluate hypotheses of decapodiform relationships by increasing taxonomic breadth and utilizing higher-quality genome and transcriptome data for several taxa. We also employ analytical approaches to (1) identify contamination in transcriptome data, (2) better assess model adequacy, and (3) account for potential biases. Using this larger data set, we consistently recover a clade comprising Myopsida (closed-eye squid), Sepiida (cuttlefishes), and Oegopsida (open-eye squid) that is sister to a Sepiolida (bobtail and bottletail squid) clade. Idiosepiida (pygmy squid) is consistently recovered as the sister group to all sampled decapodiform lineages. Further, a weighted Shimodaira-Hasegawa test applied to one of our larger data matrices rejects all alternatives to these ordinal-level relationships. At present, available nuclear genome-scale data support nested clades of relatively large-bodied decapodiform cephalopods to the exclusion of pygmy squids, but improved taxon sampling and additional genomic data will be needed to test these novel hypotheses rigorously.

Molecular characterisation and phylogenetic relationships of sedentary nematodes of the genus Meloinema Choi & Geraert, 1974 (Nematoda: Tylenchida)

Summary Molecular characterisation of two species of Meloinema: M. chitwoodi from Oregon, USA, and M. odesanens from South Korea, is given based on the partial 18S rRNA, the D2-D3 of 28S rRNA, ITS rRNA, and COI gene sequences. In the phylogenetic trees, Meloinema clustered with Meloidogyne, in a basal position and more closely with Meloidogyne indica and M. nataliei. The Shimodaira-Hasegawa (SH) maximum likelihood testing of an alternative topology with two gene fragments (D2-D3 of 28S rRNA and 18S rRNA genes) did not reject a sister relationship of Meloidogyne and Meloinema. Molecular results confirmed the view of Siddiqi (2000) that Meloidogyne and Meloinema evolved from a Pratylenchidae-type ancestor. The clade Meloinema + Meloidogyne + Nacobbus was rejected by the SH test of the D2-D3 of 28S rRNA gene sequence dataset. The molecular results suggested that the genus Nacobbus should be placed not in the Meloidogynidae, but in a separate subfamily, the Nacobbinae, under the family Pratylenchidae.

Phylogenetic relationships of Coreanomecon (Papaveraceae: Papaveroideae), an endemic genus in Korea, using DNA sequences

Coreanomecon is a monotypic and endemic genus in Korea, distributed mainly in the southern regions. Coreanomecon is morphologically similar to Hylomecon by producing red latex, easily distinguished from Chelidonium, which produces yellow latex. Coreanomecon were merged into Hylomecon or Chelidonium depending on the authors. To understand the phylogenetic relationship of Coreanomecon, DNA sequences of chloroplast rbcL and matK and nuclear Internal Transcribed Spacer (ITS) regions were determined from the species of Papaveroideae (Papaveraceae) in Korea and analyzed with the Maximum Parsimony and Bayesian methods. Phylogenetic analyses of Papaveroideae suggest that Coreanomecon is sister to the clade of Chelidonium and Stylophorum in the ITS data and that it is sister to Hylomecon in the chloroplast (cpDNA) data. A constraining analysis using the Shimodaira-Hasegawa test (S-H test) suggested that the ITS data do not reject the sister relationship of Coreanomecon and Hylomecon. The S-H test also suggested that the cpDNA data is compatible with the placement of Coreanomecon as a sister to the clade of Chelidonium and Stylophorum. Although the conflicting phylogenetic results may stem from insufficient phylogenetic signals, they may also be associated with hybridization between Hylomecon and an ancestor of Stylophorum and Chelidonium. The results of this study suggest that Coreanomecon is a distinct lineage as an endemic genus, supporting the morphological data.

Anchored hybrid enrichment phylogenomics resolves the backbone of erebine moths

The subfamily Erebinae (Lepidoptera, Erebidae) includes approximately 10,000 species with many still undescribed. It is one of the most diverse clades within the moth superfamily Noctuoidea and encompasses a diversity of ecological habits. Erebine caterpillars feed on a broad range of host plants including several economically important crops. Adults possess a unique array of adaptations for predator defense, including some of the most sensitive hearing organs (tympana) across the Lepidoptera and striking wing coloration to startle visual predators. Despite the relevance of these moths to agriculture and ecological research, a robust phylogenetic framework is lacking. Here we used anchored hybrid enrichment, a relatively new approach in phylogenomics, to resolve relationships among the subfamily. Using the recently developed Lep1 anchored hybrid enrichment probe set, 658 gene fragments with an average length of 320 bp were captured from an exemplar set of 75 erebine species, representing 73 genera and 23 tribes. While the total number of erebine tribes is not firmly established, this represents at least 75% of known tribal level diversity. Anchored hybrid enrichment data were partitioned by locus and by codon position for maximum likelihood phylogenetic analysis and coalescent-based species-tree approaches. Results from our study provided strong nodal support (BP ≥ 95) for nearly all nodes in the partitioned ML tree, solidifying many relationships that were previously uncertain or moderately supported based on morphology or a smaller number of gene fragments. Likelihood analyses confidently resolved the placement of Acantholipini as a sister tribe to Sypnini and all other Erebinae. The remaining tribes were placed in a single, strongly supported clade split into two major subclades. Additionally, 25 tropical species that did not have previous tribal assignments are confidently placed on the phylogeny. Statistical comparisons with Shimodaira-Hasegawa (SH) tests found that our maximum likelihood trees were significantly more likely than alternative hypotheses. This study demonstrates the utility of anchored phylogenomics for resolving relationships within subfamilies of Lepidoptera.

Diversifying into the branches: Species boundaries in African green and bush snakes, Philothamnus (Serpentes: Colubridae)

The African green and bush snakes of the genus Philothamnus currently comprises 21 species and three subspecies and occurs throughout sub-Saharan Africa. The genus has been the subject of previous taxonomic revisions based on traditional morphological characters and limited genetic assessment, and may not reflect their evolutionary history. Indeed, previous findings based on phylogenetics show discordant results of interspecific relationships and question the monophyly of the genus, although taxon sampling has been limited to date. We investigated phylogenetic affinities within Philothamnus with more inclusive genetic and geographical sampling, with the aim of better understanding their evolutionary history, so that future taxonomic revision of Philothamnus can be better informed. Species relationships were examined within a phylogenetic context and sampling included 133 ingroup samples from 16 taxa. Phylogenies were constructed in Bayesian and likelihood frameworks using three mitochondrial (16S, cyt b and ND4) and two nuclear (c-mos and RAG1) markers. Competing hypotheses relating to the monophyly of the genus were tested with a Shimodaira-Hasegawa test. To examine species boundaries, Bayesian General Mixed Yule-Coalescent Model and multi-rate Poisson Tree Processes analyses were conducted. In addition, a barcoding approach was used to further clarify species-level relationships by comparing frequency distributions between intra- and interspecific sequence divergence. The genus was recovered as monophyletic; however, species-delimitation results suggest that the current taxonomy does not reflect the evolutionary history of this group. For example, Philothamnus s. semivariegatus is paraphyletic, with at least four distinct clades. Philothamnus carinatus consists of two cryptic (sister) lineages from Central and West Africa that are deeply divergent, suggesting a long history of isolation between those regions. Furthermore, the subspecies P. n. natalensis and P. n. occidentalis show strong support for species-level divergence, which reflects their morphological and ecological differences. Accordingly, we elevate P. occidentalisnov. comb. to a full species. A fully informed taxonomic revision of these taxa will require additional morphological and ecological data for corroboration, but it seems that the morphological characters (e.g. scalation, dentition) used to describe these species to date are labile within and between species. This most likely has clouded our understanding of the species boundaries within the genus. Our phylogeny and species-delimitation analyses should provide a sounder framework for taxonomy, but may also prove useful toward understanding the morphological adaptations of these species to their respective habitats.

Mitochondrial phylogeny, divergence history and high-altitude adaptation of grassland caterpillars (Lepidoptera: Lymantriinae: Gynaephora) inhabiting the Tibetan Plateau

Grassland caterpillars (Lepidoptera: Lymantriinae: Gynaephora) are the most important pests in alpine meadows of the Tibetan Plateau (TP) and have well adapted to high-altitude environments. To further understand the evolutionary history and their adaptation to the TP, we newly determined seven complete TP Gynaephora mitogenomes. Compared to single genes, whole mitogenomes provided the best phylogenetic signals and obtained robust results, supporting the monophyly of the TP Gynaephora species and a phylogeny of Arctiinae + (Aganainae + Lymantriinae). Incongruent phylogenetic signals were found among single mitochondrial genes, none of which recovered the same phylogeny as the whole mitogenome. We identified six best-performing single genes using Shimodaira-Hasegawa tests and found that the combinations of rrnS and either cox1 or cox3 generated the same phylogeny as the whole mitogenome, indicating the phylogenetic potential of these three genes for future evolutionary studies of Gynaephora. The TP Gynaephora species were estimated to radiate on the TP during the Pliocene and Quaternary, supporting an association of the diversification and speciation of the TP Gynaephora species with the TP uplifts and associated climate changes during this time. Selection analyses revealed accelerated evolutionary rates of the mitochondrial protein-coding genes in the TP Gynaephora species, suggesting that they accumulated more nonsynonymous substitutions that may benefit their adaptation to high altitudes. Furthermore, signals of positive selection were detected in nad5 of two Gynaephora species with the highest altitude-distributions, indicating that this gene may contribute to Gynaephora’s adaptation to divergent altitudes. This study adds to the understanding of the TP Gynaephora evolutionary relationships and suggests a link between mitogenome evolution and ecological adaptation to high-altitude environments in grassland caterpillars.

Failure of phylogeny inferred from multilocus sequence typing to represent bacterial phylogeny

Although multilocus sequence typing (MLST) is highly discriminatory and useful for outbreak investigations and epidemiological surveillance, it has always been controversial whether clustering and phylogeny inferred from the MLST gene loci can represent the real phylogeny of bacterial strains. In this study, we compare the phylogenetic trees constructed using three approaches, (1) concatenated blocks of homologous sequence shared between the bacterial genomes, (2) genome single-nucleotide polymorphisms (SNP) profile and (3) concatenated nucleotide sequences of gene loci in the corresponding MLST schemes, for 10 bacterial species with >30 complete genome sequences available. Major differences in strain clustering at more than one position were observed between the phylogeny inferred using genome/SNP data and MLST for all 10 bacterial species. Shimodaira-Hasegawa test revealed significant difference between the topologies of the genome and MLST trees for nine of the 10 bacterial species, and significant difference between the topologies of the SNP and MLST trees were present for all 10 bacterial species. Matching Clusters and R-F Clusters metrics showed that the distances between the genome/SNP and MLST trees were larger than those between the SNP and genome trees. Phylogeny inferred from MLST failed to represent genome phylogeny with the same bacterial species.

Radopholoides japonicus n. sp. (Nematoda: Pratylenchidae) found in rhizosphere soil associated with Podocarpus macrophyllus from Japan

Radopholoides japonicusn. sp. isolated from rhizospheric soil samples associated withPodocarpus macrophyllusimported from Japan into Ningbo Port of China is described and illustrated. It is characterised by four lateral lines, lip region low, convex with three annuli. Stylet 16.5-18.5μm long with anteriorly sloping rounded knobs. Excretory pore at the level of pharyngo-intestinal junction. Vulva posteriorly located, vulval lips not protruding, spermatheca squarish. Post-vulval uterine sac 35-44μm long. Tail conoid with broadly rounded terminus, phasmid 6-8 annuli posterior to anus. Among five species of genusRadopholoides, the new species is close toR. antonibut can be differentiated from it by lip and tail morphology. This is the firstRadopholoidesspecies that provided detailed morphological and molecular characterisation. Maximum Likelihood analysis using the Shimodaira-Hasegawa test for the validity ofRadopholoideswas performed and showed the validity of the genus using the partial 18S and D2-D3 expansion segments of 28S.

Mitochondrial comparative genomics and phylogenetic signal assessment of mtDNA among arbuscular mycorrhizal fungi

Mitochondrial (mt) genes, such as cytochrome C oxidase genes (cox), have been widely used for barcoding in many groups of organisms, although this approach has been less powerful in the fungal kingdom due to the rapid evolution of their mt genomes. The use of mt genes in phylogenetic studies of Dikarya has been met with success, while early diverging fungal lineages remain less studied, particularly the arbuscular mycorrhizal fungi (AMF). Advances in next-generation sequencing have substantially increased the number of publically available mtDNA sequences for the Glomeromycota. As a result, comparison of mtDNA across key AMF taxa can now be applied to assess the phylogenetic signal of individual mt coding genes, as well as concatenated subsets of coding genes. Here we show comparative analyses of publically available mt genomes of Glomeromycota, augmented with two mtDNA genomes that were newly sequenced for this study (Rhizophagus irregularis DAOM240159 and Glomus aggregatum DAOM240163), resulting in 16 complete mtDNA datasets. R. irregularis isolate DAOM240159 and G. aggregatum isolate DAOM240163 showed mt genomes measuring 72,293bp and 69,505bp with G+C contents of 37.1% and 37.3%, respectively. We assessed the phylogenies inferred from single mt genes and complete sets of coding genes, which are referred to as “supergenes” (16 concatenated coding genes), using Shimodaira–Hasegawa tests, in order to identify genes that best described AMF phylogeny. We found that rnl, nad5, cox1, and nad2 genes, as well as concatenated subset of these genes, provided phylogenies that were similar to the supergene set. This mitochondrial genomic analysis was also combined with principal coordinate and partitioning analyses, which helped to unravel certain evolutionary relationships in the Rhizophagus genus and for G. aggregatum within the Glomeromycota. We showed evidence to support the position of G. aggregatum within the R. irregularis ‘species complex’.

Testing monophyly of the freshwater fishLeporinus(Characiformes, Anostomidae) through molecular analysis

Monophyly of the genus Leporinus (Characiformes: Anostomidae) was tested by sequencing and analysing a total of 4732 bp, including two mitochondrial [cytochrome oxidase subunit 1 (CO1) and cytochrome b (Cytb)] and three nuclear [myosin heavy chain 6 cardiac muscle alpha (Myh6), recombination activating gene 1 (RAG1) and recombination activating gene 2 (RAG2)] loci for 22 species of Leporinus, or c. 25% of all described species in the genus. Phylogenetic tree analyses (maximum parsimony, maximum likelihood and Bayesian species tree) indicate Leporinus to be paraphyletic, with monophyly being rejected by both Kishino-Hasegawa and Shimodaira-Hasegawa tests. The sequenced species of Leporinus are distributed across five clades that are interleaved among other anostomid genera. Several taxonomic changes are suggested as being necessary to restore monophyly for the group. The clade containing the type species, Leporinus fasciatus, should be considered Leporinus sensu stricto and at least three new genera should be described for other species currently considered part of Leporinus.

Hoplotylus femina s’Jacob, 1960 (Nematoda: Pratylenchidae) from Spain with molecular phylogenetic relationships inferred by D2-D3 expansion fragments of 28S and the partial 18S rRNA gene sequences

This is the first report of Hoplotylus femina in Spain. It was collected from the rhizosphere and roots of common alder (Alnus glutinosa) in La Alberca, Salamanca Province, in Spain. The morphology and morphometrics of the Spanish population of H. femina agree closely with the original description of the species and other descriptions from The Netherlands, USA, New Zealand, Poland, Japan and Mexico. Only small differences in some morphological characters were found probably due to geographical intraspecific variability and/or different methods of fixing nematodes. This study provides new molecular markers for species identification (D2-D3 expansion regions of 28S and ITS-rRNA genes) and a new phylogenetic position for the D2-D3 region marker. Maximum likelihood analysis using the Shimodaira-Hasegawa test did not support the inclusion of Radopholus and Hoplotylus in the Pratylenchidae and both genera were more related phylogenetically to Hoplolaimidae.

Armored scale insect endosymbiont diversity at the species level: genealogical patterns of Uzinura diasipipdicola in the Chionaspis pinifoliae-Chionaspis heterophyllae species complex (Hemiptera: Coccoidea: Diaspididae).

Armored scale insects and their primary bacterial endosymbionts show nearly identical patterns of co-diversification when viewed at the family level, though the persistence of these patterns at the species level has not been explored in this group. Therefore we investigated genealogical patterns of co-diversification near the species level between the primary endosymbiont Uzinura diaspidicola and its hosts in the Chionaspis pinifoliae-Chionaspis heterophyllae species complex. To do this we generated DNA sequence data from three endosymbiont loci (rspB, GroEL, and 16S) and analyzed each locus independently using statistical parsimony network analyses and as a concatenated dataset using Bayesian phylogenetic reconstructions. We found that for two endosymbiont loci, 16S and GroEL, sequences from U. diaspidicola were broadly associated with host species designations, while for rspB this pattern was less clear as C. heterophyllae (species S1) shared haplotypes with several other Chionaspis species. We then compared the topological congruence of the phylogenetic reconstructions generated from a concatenated dataset of endosymbiont loci (including all three loci, above) to that from a concatenated dataset of armored scale hosts, using published data from two nuclear loci (28S and EF1α) and one mitochondrial locus (COI-COII) from the armored scale hosts. We calculated whether the two topologies were congruent using the Shimodaira-Hasegawa test. We found no significant differences (P = 0.4892) between the topologies suggesting that, at least at this level of resolution, co-diversification of U. diaspidicola with its armored scale hosts also occurs near the species level. This is the first such study of co-speciation at the species level between U. diaspidicola and a group of armored scale insects.

Population genetic analysis of Streptomyces albidoflavus reveals habitat barriers to homologous recombination in the diversification of streptomycetes.

Examining the population structure and the influence of recombination and ecology on microbial populations makes great sense for understanding microbial evolution and speciation. Streptomycetes are a diverse group of bacteria that are widely distributed in nature and a rich source of useful bioactive compounds; however, they are rarely subjected to population genetic investigations. In this study, we applied a five-gene-based multilocus sequence analysis (MLSA) scheme to 41 strains of Streptomyces albidoflavus derived from diverse sources, mainly insects, sea, and soil. Frequent recombination was detected in S. albidoflavus, supported by multiple lines of evidence from the pairwise homoplasy index (Φw) test, phylogenetic discordance, the Shimodaira-Hasegawa (SH) test, and network analysis, underpinning the predominance of homologous recombination within Streptomyces species. A strong habitat signal was also observed in both phylogenetic and Structure 2.3.3 analyses, indicating the importance of ecological difference in shaping the population structure. Moreover, all three habitat-associated groups, particularly the entomic group, demonstrated significantly reduced levels of gene flow with one another, generally revealing habitat barriers to recombination. Therefore, a combined effect of homologous recombination and ecology is inferred for S. albidoflavus, where dynamic evolution is at least partly balanced by the extent that differential distributions of strains among habitats limit genetic exchange. Our study stresses the significance of ecology in microbial speciation and reveals the coexistence of homologous recombination and ecological divergence in the evolution of streptomycetes.

Molecular phylogeny of Plumbaginaceae with emphasis on Acantholimon Boiss. based on nuclear and plastid DNA sequences in Iran

The present study represents phylogenetic analyses of Plumbaginaceae with emphasis on Acantholimon from Iran using nrDNA ITS and plastid trnY-T sequences. The analyses support the monophyly and the close relationship of Limonium, Armeria and Psylliostachys. This is the first report of the close relationship between Acantholimon and Cephalorhizum. The data for the position of Cephalorhizum is unclear. The Shimodaira–Hasegawa test of nrDNA ITS and the combined datasets indicated that Acantholimon and Cephalorhizum are distinct genera. The molecular data revealed that the traditionally recognized multi-specific Acantholimon sections (Acantholimon, Acmostegia, Glumaria, Microstegia, Staticopsis and Tragacanthina) are not monophyletic. Their members are intermixed with each other and scattered across the Acantholimon clade, but the smaller sections including Platystegia and Pterostegia, each comprising two species, are monophyletic.

Phylogenetic signal detection from an ancient rapid radiation: Effects of noise reduction, long-branch attraction, and model selection in crown clade Apocynaceae

Crown clade Apocynaceae comprise seven primary lineages of lianas, shrubs, and herbs with a diversity of pollen aggregation morphologies including monads, tetrads, and pollinia, making them an ideal group for investigating the evolution and function of pollen packaging. Traditional molecular systematic approaches utilizing small amounts of sequence data have failed to resolve relationships along the spine of the crown clade, a likely ancient rapid radiation. The previous best estimate of the phylogeny was a five-way polytomy, leaving ambiguous the homology of aggregated pollen in two major lineages, the Periplocoideae, which possess pollen tetrads, and the milkweeds (Secamonoideae plus Asclepiadoideae), which possess pollinia. To assess whether greatly increased character sampling would resolve these relationships, a plastome sequence data matrix was assembled for 13 taxa of Apocynaceae, including nine newly generated complete plastomes, one partial new plastome, and three previously reported plastomes, collectively representing all primary crown clade lineages and outgroups. The effects of phylogenetic noise, long-branch attraction, and model selection (linked versus unlinked branch lengths among data partitions) were evaluated in a hypothesis-testing framework based on Shimodaira–Hasegawa tests. Discrimination among alternative crown clade resolutions was affected by all three factors. Exclusion of the noisiest alignment positions and topologies influenced by long-branch attraction resulted in a trichotomy along the spine of the crown clade consisting of Rhabdadenia+the Asian clade, Baisseeae+milkweeds, and Periplocoideae+the New World clade. Parsimony reconstruction on all optimal topologies after noise exclusion unambiguously supports parallel evolution of aggregated pollen in Periplocoideae (tetrads) and milkweeds (pollinia). Our phylogenomic approach has greatly advanced the resolution of one of the most perplexing radiations in Apocynaceae, providing the basis for study of convergent floral morphologies and their adaptive value.

Describing a New Species into a Polyphyletic Genus: Taxonomic Novelty in <I>Ledermanniella</I> s.l. (Podostemaceae) from Cameroon

Abstract Ledermanniella s.l. (Podostemaceae) occurs in western Africa, where species are commonly localized to single rapids or waterfalls. Recent collecting efforts in this region have led to the discovery of new species diversity; however, molecular phylogenetic analyses estimate the genus as polyphyletic and associated with at least nine other genera. Here, we describe a new species of Ledermanniella s.l. while addressing the problem of describing a species into a polyphyletic genus with a phylogenetic approach. We sampled species diversity for molecular and morphological data and combined them with morphological data only from the new species, which we were unable to sequence because of non-optimal DNA preservation or other reasons. We tested and rejected the monophyly of Ledermanniella s.l. and L. subgenus Ledermanniella with the Shimodaira-Hasegawa test, and found support for a monophyletic L. subgenus Phyllosoma, which was recently treated at the genus level as Inversodicraea. Based on Bayesian phy...

Molecular Phylogeny of the Genus Lathyrus (Fabaceae-Fabeae) Based on cpDNA matK Sequence in Iran

Background: More than 60 species of the genus Lathyrus are distributed in Southwest Asia. It is the second largest genus of the tribe Fabeae, after Vicia, in the region (and in Iran with 23 species). In the regional Flora (Flora of Turkey, Flora Iranica and flora of Iran), the genus has been divided into 9-10 sections. Here we analyzed the phylogeny of Lathyrus and its relationship with Pisum based on plastid gene matK sequences. Objectives: The present study utilized several approaches including maximum parsimony, Bayesian and maximum likelihood methods to evaluate the monophyly and relationship within the genus Lathyrus, both at the sectional level and species level, mainly based on the taxa growing in Iran. Materials and Methods: A total of 52 accessions, representing 38 species of Lathyrus, three species of Pisum and four species of Vicia and Lens as out-groups, were analyzed for reconstructing the phylogenetic relationship using chloroplast gene matK sequences. Maximum parsimony, Bayesian and maximum likelihood methods were used to construct phylogenetic trees. Results: The present study indicated that Pisum was nested among Lathyrus species. Two members of the Lathyrus section, Clymenum (Lathyrus ochrus and L. Clymenum) with Pisum, formed a weakly supported clade as sister to the larger polytomy comprising the remainder of the Lathyrus species. Several sections of Lathyrus including Lathyrostylis, Lathyrus and Clymenum were monophyletic. Lathyrus roseus (of the monotypic section Orobon) were nested among the members of section Lathyrus. The newly taxon described species L. alamutensis, endemic to Iran, were nested among other species of Lathyrostylis. Linearicarpus, Orobus and Pratensis were not monophyletic sections. Pratensis and the monotypic section Aphaca were the closest taxa. In our analysis, L. Pratensis formed a sister group relationship with the Aphaca clade, not its own section. Conclusions: Shimodaira-Hasegawa (SH) test of the matK data set showed that all of the analyzed Lathyrus species formed their own clade and Pisum was sister to them. Furthermore, when we removed the two above-mentioned Lathyrus species, the analysis retrieved Pisum, as a well-supported clade being sister to the Lathyrus calde.

Molecular phylogeny, diagnostics, and diversity of plant-parasitic nematodes of the genusHemicycliophora(Nematoda: Hemicycliophoridae)

The genus Hemicycliophora (Nematoda: Hemicycliophoridae) contains 132 valid species of plant-parasitic nematodes, collectively known as ‘sheath nematodes’. Hemicycliophora spp. are characterized morphologically by a long stylet with rounded basal knobs and a cuticular sheath, present in juvenile and adult stages. Populations of 20 valid and 14 putative species of Hemicycliophora and Loofia from several countries were characterized morphologically using light (LM) and scanning electron microscopy (SEM) and molecularly using the D2-D3 segments of 28S rRNA and internal transcribed spacer (ITS) rRNA gene sequences. LM and SEM observations provided new details on the morphology of these species. PCR-restriction fragment length polymorphisms (PCR-RFLPs) of the D2-D3 of 28S rDNA were proposed for identification of the species. Phylogenetic relationships within populations of 36 species of the genus Hemicycliophora using 102 D2-D3 of 28S rDNA and 97 ITS rRNA gene sequences as inferred from Bayesian analysis are reconstructed and discussed. Ancestral state reconstructions of diagnostic characters (body and stylet length, number of body annuli, shape of vulval lip and tail), using maximum parsimony and Bayesian inference, revealed that none of the traits are individually reliable characters for classifying the studied sheath nematode. The Shimodaira–Hasegawa test rejected the validity of the genus Loofia. This is the most complete phylogenetic analysis of Hemicycliophora species conducted so far. © 2014 The Linnean Society of London