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1.
Ribbon worm relationships: a phylogeny of the phylum Nemertea   总被引:8,自引:0,他引:8  
We present the most extensive phylogenetic analysis to date, to our knowledge, of higher-level nemertean relationships, based on sequence data from four different genes (the nuclear genes for nuclear large subunit rRNA (28S rRNA) and histone H3 (H3), and the mitochondrial genes for mitochondrial large subunit rRNA (16S rRNA) and cytochrome c oxidase subunit I (COI)). Well-supported clades are, in general, compatible with earlier, more limited, analyses, and current classification is largely in agreement with our results, although there are some notable exceptions. Bdellonemertea (represented by Malacobdella) is found to be a part of Monostilifera, and Polystilifera is the monophyletic sister group to Monostilifera. Cratenemertidae is the sister group to the remaining monostiliferans (including Malacobdella), a group to which we apply the new name Distromatonemertea. Heteronemertea is monophyletic and forms a clade with Hubrechtella; for this clade we introduce the name Pilidiophora. Finally, Pilidiophora and Hoplonemertea (with Malacobdella) form a monophyletic group, and we introduce the name Neonemertea to refer to this group. Palaeonemertea is found to be non-monophyletic and basal among nemerteans.  相似文献   

2.
Although the monophyly of Nemertea is strongly supported by unique morphological characters and results of molecular phylogenetic studies, their ingroup relationships are largely unresolved. To contribute solving this problem we studied sperm ultrastructure of 12 nemertean species that belong to different subtaxa representing the commonly recognized major monophyletic groups. The study yielded a set of 26 characters with an unexpected variation among species of the same genus (Tubulanus and Procephalothrix species), whereas other species varied in metric values or only one character state (Ramphogordius). In some species, the sperm nucleus has grooves (Zygonemertes virescens, Amphiporus imparispinosus) that may be twisted and give a spiral shape to the sperm head (Paranemertes peregrina, Emplectonema gracile). To make the characters from sperm ultrastructure accessible for further phylogenetic analyses, they were coded in a character matrix. Published data for eight species turned out to be sufficiently detailed to be included. Comparative evaluation of available information on the sperm ultrastructure suggests that subtaxa of Heteronemertea and Hoplonemertea are supported as monophyletic by sperm morphology. However, the data do not provide information on the existing contradictions regarding the internal relationships of “Palaeonemertea.” Nevertheless, our study provides evidence that sperm ultrastructure yields numerous potentially informative characters that will be included in upcoming phylogenetic analyses. J. Morphol. 2010. © 2010 Wiley‐Liss, Inc.  相似文献   

3.
Food, Feeding Behavior and Feeding Ecology of Nemerteans   总被引:12,自引:1,他引:11  
The feeding biology of nemerteans is reviewed, new informationis presented, and the role of nemerteans in natural communitiesis discussed and evaluated. Most nemerteans are carnivorous,the majority feeding on live, often specific, prey, while someare scavengers. Macrophagous feeding is found in the Palaeonemertea,Heteronemertea and some of the Hoplonemertea; the more specializedsuctorial feeding is limited to five of the hoplonemertean families,and suspension feeding (omnivorous diet) occurs only in thehighly specialized symbiotic monogeneric Bdellonemertea. Feeding adaptations seem to be related to the nature and employmentof the proboscis, the dilatability of the mouth, and the structureof the anterior part of the digestive tract. The transport ofdissolved organic materials from seawater has been demonstrated,but its role in nemertean nutrition is just being contemplated.Present meager information on predation has shown nemerteansto have actually and potentially large effects on prey populationsand thus on the communities in which they live. As the feedingbiology of only a relative handful of species has been studied,much basic comparative research is needed before we can corroborateor refute our present ideas concerning the ecological rolesof nemerteans.  相似文献   

4.
Abstract— Numerical phylogenetic analysis of nemertean species from the genera Plectonemertes, Katechonemertes and Acteonementes (marine), Argonemertes, Antiponemertes and Leptonemertes (terrestrial), Potamonemertes and Campbellonemertes (freshwater) in the family Plectonemertidae was carried out with the following aims. (1) To estimate the evolutionary relationships between and among these species. (2) To lest the hypothesis of Moore and Gibson that the analysed freshwater species originated from a terrestrial ancestor. (3) To classify the species in monophyletic genera. The analysis did not confirm the hypothesis that the freshwater habitat has been colonised via land. Instead, it suggests that both terrestrial and freshwater species within this family have evolved from a marine ancestor. The cladogram suggests that Antiponemetes is paraphyletic, and it is combined with Argonemertes to form a monophyletic genus.  相似文献   

5.
The first comprehensive analysis of higher‐level phylogeny of the order Hymenoptera is presented. The analysis includes representatives of all extant superfamilies, scored for 392 morphological characters, and sequence data for four loci (18S, 28S, COI and EF‐1α). Including three outgroup taxa, 111 terminals were analyzed. Relationships within symphytans (sawflies) and Apocrita are mostly resolved. Well supported relationships include: Xyeloidea is monophyletic, Cephoidea is the sister group of Siricoidea + [Xiphydrioidea + (Orussoidea + Apocrita)]; Anaxyelidae is included in the Siricoidea, and together they are the sister group of Xiphydrioidea + (Orussoidea + Apocrita); Orussoidea is the sister group of Apocrita, Apocrita is monophyletic; Evanioidea is monophyletic; Aculeata is the sister group of Evanioidea; Proctotrupomorpha is monophyletic; Ichneumonoidea is the sister group of Proctotrupomorpha; Platygastroidea is sister group to Cynipoidea, and together they are sister group to the remaining Proctotrupomorpha; Proctotrupoidea s. str. is monophyletic; Mymarommatoidea is the sister group of Chalcidoidea; Mymarommatoidea + Chalcidoidea + Diaprioidea is monophyletic. Weakly supported relationships include: Stephanoidea is the sister group of the remaining Apocrita; Diaprioidea is monophyletic; Ceraphronoidea is the sister group of Megalyroidea, which together form the sister group of [Trigonaloidea (Aculeata + Evanioidea)]. Aside from paraphyly of Vespoidea within Aculeata, all currently recognized superfamilies are supported as monophyletic. The diapriid subfamily Ismarinae is raised to family status, Ismaridae stat. nov. © The Will Henning Society 2011.  相似文献   

6.
The chloroplast-encoded atp B gene was sequenced from 33 strains representing 28 species of the colonial Volvocales (the Volvocaceae and its relatives) to reexamine phylogenetic relationships as previously deduced by morphological data and rbc L gene sequence data.1128 base pairs in the coding regions of the atp B gene were analyzed by MP, NJ, and ML analyses. Although supported with relatively low bootstrap values (75% and 65% in the NJ and ML analyses, respectively), three anisogamous/oogamous volvocacean genera— Eudorina, Pleodorina, and Volvox, excluding the section Volvox (= Euvolvox, illegitimate name), constituted a large monophyletic group (Eudorina group). Outside the Eudorina group, a robust lineage composed of three species of Volvox sect. Volvox was resolved as in the rbc L gene trees, rejecting the hypothesis of the previous cladistic analysis based on morphological data that the genus Volvox is monophyletic. In addition, the NJ and ML trees suggested that Eudorina is a nonmonophyletic genus as inferred from the morphological data and rbc L gene sequences. Although phylogenetic status of the genus Gonium is ambiguous in the rbc L gene trees and the paraphyly of this genus is resolved in the cladistic analysis based on morphological data, the atp B gene sequence data suggest monophyly of Gonium with relatively low bootstrap values (56–61%) in the NJ and ML trees. On the basis of the combined sequence data (2256 base pairs) from atp B and rbc L genes, Gonium was resolved as a robust monophyletic genus in the NJ and ML trees (with 68–86% bootstrap values), and Eudorina elegans Ehrenberg represented a paraphyletic species positioned most basally within the Eudorina group. However, phylogenetic status and relationships of the families of the colonial Volvocales were still almost ambiguous even in the combined analysis.  相似文献   

7.
We investigated phylogenetic and biogeographic relationships within Juglans (walnuts), a Tertiary disjunct genus, using 15 species of Juglans and related (Juglandaceae) outgroups. The relationships were analyzed using nucleotide sequences of the chloroplast gene matK and its flanking spacers and of the internal transcribed spacers (ITS) and 5.8S gene of the nuclear ribosomal DNA. The DNA sequences provided 246 informative characters for parsimony analysis. ITS data supported as monophyletic groups the four generic sections, Cardiocaryon, Dioscaryon, Rhysocaryon, and Trachycaryon. Within Rhysocaryon, the temperate black walnuts and the tropical black walnuts were supported as monophyletic groups. When the two data sets were combined, J. cinerea was nested within Cardiocaryon. Combined analysis with published nuclear DNA restriction site data placed J. cinerea in a monophyletic group with Cardiocaryon. These analyses consistently supported Juglans as a monophyletic group and as the sister group to the genus Pterocarya. The results of this work are consistent with the known geological history of Juglans. The fossil record suggests that the butternuts had evolved by the early Oligocene in North America. The presence of butternuts in Eurasia could be the result of migration from North America to Eurasia during the warming trend of the mid Oligocene.  相似文献   

8.
A new species of conifer was recently discovered in northern Vietnam. In a preliminary phylogenetic analysis of morphological data a possible sister species, Chamaecyparis nootkatensis (D. Don) Spach, was identified; however, because of the presumed phylogenetic remoteness of these two species to the remainder of the Cupressaceae, a new genus-Xanthocyparis-was described to accommodate both species. Here an analysis of ITS (nrDNA), matK, and rbcL sequence data in combination with 58 informative morphological characters was aimed at testing the monophyly of the remainder of Chamaecyparis and evaluating the placement and monophyly of Xanthocyparis. Chamaecyparis, minus C. nootkatensis, was resolved as a monophyletic group, remote from Cupressus and Xanthocyparis. Cupressus, Juniperus, and Xanthocyparis formed a very highly supported monophyletic group. However, Cupressus was not monophyletic. Instead the Old World species sampled were resolved sister to a clade containing a monophyletic Juniperus, a monophyletic Xanthocyparis, and a clade of New World Cupressus species. If both species of Xanthocyparis are to be treated as members of the same genus, then due to the principal of priority they will have to be recognized in the genus Callitropsis. Research is continuing to resolve the status of New World and Old World Cupressus.  相似文献   

9.
A phylogeny of all eight recognized taxa of the genus Thunnus was constructed from approximately 400 base pairs of sequence of the mitochondrial DNA (mtDNA) control region. The PCR-amplified control region I segment studied contained a total of 186 variable sites and 159 phylogenetically informative sites. Diagnostic sequences for every taxon were identified. Neighbour-joining phylogenies supported monophyletic origins of the temperate subgenus Thunnus and of the tropical subgenus Neothunnus . Similar results were obtained by maximum parsimony analyses except that there was no support for a monophyletic origin of the subgenus Thunnus . Bigeye tuna, which have been difficult to place in either subgenus using conventional morphological data, was identified as the sister species of Neothunnus . Within the subgenus Thunnus , the Atlantic bluefin and Southern bluefin tunas were shown to be sister taxa of the highly divergent monophyletic clade formed by the Pacific northern bluefin and the Albacore tunas. The conspecific Atlantic ( T. thynnus thynnus ) and Pacific ( T. t. orientalis ) northern bluefin tunas were more divergent (Tamura-Nei distance 0·145 ± 0·019) from each other than the average distance separating most species-pairs within the genus. Thus, a re-examination of their status as subspecies of T. thunnus is warranted.  相似文献   

10.
DNA sequence data from the chloroplast gene ndhF were analyzed to estimate the phylogeny of the subfamily Panicoideae, with emphasis on the tribe Paniceae. Our data suggest that the subfamily is divided into three strongly supported clades, corresponding to groups with largely identical base chromosome numbers. Relationships among the three clades are unclear. In unweighted parsimony analyses, the two major clades with x = 10 (Andropogoneae and x = 10 Paniceae) are weakly supported as sister taxa. The third large clade corresponds to x = 9 Paniceae. In analyses under implied weight, the two clades of Paniceae are sisters, making the tribe monophyletic. Neither resolution is strongly supported.Our molecular phylogenies are not congruent with previous classifications of tribes or subtribes. Based on this sample of species, we infer that C(4) photosynthesis has evolved independently several times, although a single origin with multiple reversals and several reacquisitions is only slightly less parsimonious. The phosphoenol pyruvate carboxykinase (PCK) subtype of C(4) photosynthesis has evolved only once, as has the NAD-malic enzyme (ME) subtype; all other origins are NADP-ME. Inflorescence bristles are apparently homologous in the genera Setaria and Pennisetum, contrary to opinions of most previous authors. Some genera, such as Digitaria, Echinochloa, and Homolepis are supported as monophyletic. The large genus Paspalum is shown to be paraphyletic, with Thrasya derived from within it. As expected, Panicum is polyphyletic, with lineages derived from multiple ancestors across the tree. Panicum subg. Panicum is monophyletic. Panicum subg. Dichanthelium, subg. Agrostoides, and subg. Phanopyrum are unrelated to each other, and none is monophyletic. Only Panicum subg. Dichanthelium sect. Dichanthelium, represented by P. sabulorum and P. koolauense, is monophyletic. Panicum subg. Megathyrsus, a monotypic subgenus including only the species P. maximum, is better placed in Urochloa, as suggested by other authors.  相似文献   

11.
Amiskwia sagittiformis Walcott is redescribed on the basis of the five available specimens. The dorsoventrally compressed body consists of a head bearing a pair of prominent tentacles and a trunk with lateral and caudal fins. A gut with subterminal openings, cerebral ganglia, nerve cords, blood vessels and muscles have been identified with varying degrees of confidence. An active pelagic mode of life is considered probable. The rejection by earlier workers of this worm from the arrow-worms (Chaetognatha) is confirmed, but their identification of it as a nemertean (Nemertea) cannot be supported owing to the absence of critical data. The systematic position ofA. sagittiformis remains unresolved.  相似文献   

12.
Phylogeny of Ephemeroptera (mayflies) based on molecular evidence   总被引:1,自引:0,他引:1  
This study represents the first molecular phylogeny for the Order Ephemeroptera. The analyses included 31 of the 37 families, representing approximately 24% of the genera. Fifteen families were supported as being monophyletic, five families were supported as nonmonophyletic, and 11 families were only represented by one species, and monophyly was not testable. The suborders Furcatergalia and Carapacea were supported as monophyletic while Setisura and Pisciforma were not supported as monophyletic. The superfamilies Ephemerelloidea and Caenoidea were supported as monophyletic while Baetoidea, Siphlonuroidea, Ephemeroidea, and Heptagenioidea were not. Baetidae was recovered as sister to the remaining clades. The mayfly gill to wing origin hypothesis was not supported nor refuted by these data. Mandibular tusks were supported as having at least one loss in Behningiidae and, together with the burrowing lifestyle, possibly two origins. The fishlike body form was supported as plesiomorphic for mayflies with multiple secondary losses. Topological sensitivity analysis was used as a tool to examine patterns concerning the stability of relationships across a parameter landscape, providing additional information that may not have been acquired otherwise.  相似文献   

13.
Large subunit ribosomal DNA (LSU rDNA) sequence data from 120 taxa and cytochrome oxidase subunit 1(COI) sequence data from 27 taxa are analyzed separately and together to estimate the internal phylogeny of the class Demospongiae and to evaluate how consistent these data are with pre-existing hypotheses of relationship concerning order-level monophyly and relationships. The monophyly of Porifera is only slightly inconsistent with LSU data, which do not support the monophyly of the class Demospongiae regardless of the inclusion or exclusion of Homoscleromopha (this result is likely due to the placement of a single hexactinellid taxon within the Demospongiae), however, no LSU support is found for the monophyly of Silicea (Demospongiae+Hexactinellida) unless homoscleromorphs are excluded. Neither the subclasses Ceractinomorpha and Tetractinomorpha, nor the orders Halichondrida, Hadromerida, and Haplosclerida are supported as monophyletic under any data partition. The haplosclerid suborders Haplosclerina and Petrosina are supported as monophyletic to the exclusion of the suborder Spongillina, and the orders Dictyoceratida, Verongida, Poecilosclerida, Astrophorida, Spirophorida, Homosclerophorida, and Agelasida are largely reconstructed as monophyletic, with the exception of few anomalously placed taxa. Few inter-order relationships are strongly supported by any data partition, but there is moderate support for a verongid+chondrosid clade and a tetractinellid+halichondrid clade. Furthermore, LSU data strongly support the existence of two novel clades that do not correspond to the existing classification and that show no morphological uniformity. Finally, every data partition supports the monophyly of a clade that includes the order Agelasida, some members of the genus Axinella, and two taxa tentatively identified as belonging to the orders Hadromerida and Halichondrida.  相似文献   

14.
DNA studies of 23 taxa (20 platyhelminths, 1 nemertean, Homo and Artemia) and electron-microscopic studies of the protonephridia of many platyhelminths (supported by some additional ultrastructural data) have led to the following conclusions: the Neodermata are monophyletic; Temnocephalida and Dalyelliida form one clade and are not the primitive sister group of the Neodermata; Gyrocotylidea, Amphilinidea and Eucestoda form one monophylum; Pterastericolidae and Umagillidae are dalyelliids and not the sister group of the Neodermata; and Proseriata are unlikely to be closely related with the Tricladida. A large taxon consisting of the Proseriata and some other turbellarians may represent the sister group of the Neodermata.  相似文献   

15.
Tetraodontiform fishes (e.g., triggerfishes, boxfishes, pufferfishes, and giant ocean sunfishes) have long been recognized as a monophyletic group. Morphological analyses have resulted in conflicting hypotheses of relationships among the tetraodontiform families. Molecular data from the single-copy nuclear gene RAG1 and from two mitochondrial ribosomal genes, 12S and 16S, were used to test these morphology-based hypotheses. Total evidence (RAG1+12S+16S), RAG1-only, and mitochondrial-only analyses were performed using both maximum parsimony and Bayesian criteria. Total evidence and RAG1-only analyses recover a monophyletic Tetraodontiformes. However, the relationships recovered within the order differ, and none completely conform to previous hypotheses. Analysis of mitochondrial data alone fails to recover a monophyletic Tetraodontiformes and therefore does not support any of the morphology-based topologies. The RAG1 data appear to give the best estimate of tetraodontiform phylogeny, resulting in many strongly supported nodes and showing a high degree of congruence between both parsimony and Bayesian analyses. All analyses recover every tetraodontiform family for which more than one representative is included as a strongly supported monophyletic group. Balistidae and Monacanthidae are recovered as sister groups with robust support in every analysis, and all analyses except the Bayesian analyses of the mitochondrial data alone recover a strongly supported sister-group relationship between Tetraodontidae and Diodontidae. Many of the intrafamilial relationships recovered from the molecular data presented here corroborate previous morphological hypotheses.  相似文献   

16.
Pezizomycotina is the largest subphylum of Ascomycota and includes the vast majority of filamentous, ascoma-producing species. Here we report the results from weighted parsimony, maximum likelihood and Bayesian phylogenetic analyses of five nuclear loci (SSU rDNA, LSU rDNA, RPB1, RPB2 and EF-lalpha) from 191 taxa. Nine of the 10 Pezizomycotina classes currently recognized were represented in the sampling. These data strongly supported the monophyly of Pezizomycotina, Arthoniomycetes, Eurotiomycetes, Orbiliomycetes and Sordariomycetes. Pezizomycetes and Dothideomycetes also were resolved as monophyletic but not strongly supported by the data. Lecanoromycetes was resolved as paraphyletic in parsimony analyses but monophyletic in maximum likelihood and Bayesian analyses. Leotiomycetes was polyphyletic due to exclusion of Geoglossaceae. The two most basal classes of Pezizomycotina were Orbiliomycetes and Pezizomycetes, both of which comprise species that produce apothecial ascomata. The seven remaining classes formed a monophyletic group that corresponds to Leotiomyceta. Within Leotiomyceta, the supraclass clades of Leotiomycetes s.s. plus Sordariomycetes and Arthoniomycetes plus Dothideomycetes were resolved with moderate support.  相似文献   

17.
A preliminary study was conducted on phylogenetic relationships among some selected genera of the Australian Spilomelini, focusing on relationships among the Australian Glyphodes group (Glyphodes Guenée, 1854, Dysallacta Lederer, 1863, Talanga Moore, 1885 and Agrioglypta Meyrick, 1932) and the 17 genera which are morphologically similar to it. Representatives of three genera of the Pyarustini were used as outgroups. Cladistic analysis of morphological data from the adult moths produced 10 equally MP trees (length = 221, CI=0.294, and RI=0.608). The clade formed by the 21 selected genera of the Australian Spilomelini had low bootstrap support even though a good apomorphy supported the monophyly of this group, namely, a strong, bilobed praecinctorium of abdominal tympanal organs. The analysis showed that the Glyphodes group is not monophyletic because the genus Chrysothyridia Snellen appears within it in the 10 MP trees. The concept of the Glyphodes group should be expanded to include Chrysothyridia and also the Synclera Zeller and Didymostoma (Walker) since the Synclera + Didymostoma clade, as the hypothesised sister group of the Glyphodes group, is not sufficiently supported as a separate monophyletic group. The analysis also showed that genus Glyphodes is not a monophyletic group, while Metallarcha Meyrick is a monophyletic group.  相似文献   

18.
Abstract.  Sympetrinae is the largest subfamily of the diverse dragonfly family Libellulidae. This subfamily, like most libellulid subfamilies, is defined currently by a few wing venation characters, none of which are synapomorphies for the taxon. In this study, we used DNA sequence data from the nuclear locus elongation factor-1α and the mitochondrial loci 16S and 12S rRNA, together with 38 wing venation characters, to test the monophyly of the Sympetrinae and several other libellulid subfamilies. No analysis recovered Sympetrinae as monophyletic, partly because of the position of Leucorrhinia (of the subfamily Leucorrhininae) as a strongly supported sister to Sympetrum (of Sympetrinae) in all analyses. The subfamilies Brachydiplactinae, Leucorrhininae, Trameinae and Trithemistinae were also found not to be monophyletic. Libellulinae was the only subfamily supported strongly as monophyletic. Consistency indices and retention indices of wing venation characters used to define various subfamilies were closer to zero than unity, showing that many of these characters were homoplasious, and therefore not useful for a classification scheme within Libellulidae.  相似文献   

19.
This study represents the first formal morphological and combined (morphological and molecular) phylogenetic analyses of the order Ephemeroptera. Taxonomic sampling comprised 112 species in 107 genera, including 42 recognized families (all major lineages of Ephemeroptera). Morphological data consisted of 101 morphological characters. Molecular data were acquired from DNA sequences of the 12S, 16S, 18S, 28S and H3 genes. The Asian genus Siphluriscus (Siphluriscidae) was supported as sister to all other mayflies. The lineages Carapacea, Furcatergalia, Fossoriae, Pannota, Caenoidea and Ephemerelloidea were supported as monophyletic, as were many of the families. However, some recognized families (for example, Ameletopsidae and Coloburiscidae) and major lineages (such as Setisura, Pisciforma and Ephemeroidea among others) were not supported as monophyletic, mainly due to convergences within nymphal characters. Clade robustness was evaluated by multiple methods and approaches.  相似文献   

20.
Phylogeny of caddisflies (Insecta, Trichoptera)   总被引:2,自引:0,他引:2  
Trichoptera are holometabolous insects with aquatic larvae that, together with the Lepidoptera, comprise the Amphiesmenoptera. Previous phylogenetic hypotheses and progress on our ongoing data collection are summarized. Fragments of the large and small subunit nuclear ribosomal RNAs (D1, D3, V4–5), the nuclear elongation factor 1 alpha gene and a fragment of mitochondrial cytochrome oxidase 1 (COI) were sequenced, and molecular data were combined with previously published morphological data. Equally and differentially weighted parsimony analyses were conducted in order to present a phylogeny of Trichoptera, including 43 of 45 families. Our phylogeny closely resembles that proposed by Herbert Ross with respect to the relationships among suborders, with a monophyletic Annulipalpia at the base of the tree, and a clade consisting of Spicipalpia plus a monophyletic Integripalpia. The monophyly of Spicipalpia is weakly supported in the combined equally weighted analysis, and Spicipalpia is paraphyletic in the differentially weighted analysis. Within Integripalpia, our phylogeny recovered monophyletic Plenitentoria, Brevitentoria and Sericostomatoidea. Leptoceroidea was unresolved in the equally weighted analysis and monophyletic in the differentially weighted analysis. Within Annulipalpia, we recovered a basal but paraphyletic Philopotamoidea and a monophyletic Hydropsychoidea.  相似文献   

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