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1.
The ordinal level phylogeny of the Arachnida and the suprafamilial level phylogeny of the Opiliones were studied on the basis of a combined analysis of 253 morphological characters, the complete sequence of the 18S rRNA gene, and the D3 region of the 28S rRNA gene. Molecular data were collected for 63 terminal taxa. Morphological data were collected for 35 exemplar taxa of Opiliones, but groundplans were applied to some of the remaining chelicerate groups. Six extinct terminals, including Paleozoic scorpions, are scored for morphological characters. The data were analyzed using strict parsimony for the morphological data matrix and via direct optimization for the molecular and combined data matrices. A sensitivity analysis of 15 parameter sets was undertaken, and character congruence was used as the optimality criterion to choose among competing hypotheses. The results obtained are unstable for the high-level chelicerate relationships (except for Tetrapulmonata, Pedipalpi, and Camarostomata), and the sister group of the Opiliones is not clearly established, although the monophyly of Dromopoda is supported under many parameter sets. However, the internal phylogeny of the Opiliones is robust to parameter choice and allows the discarding of previous hypotheses of opilionid phylogeny such as the "Cyphopalpatores" or "Palpatores." The topology obtained is congruent with the previous hypothesis of "Palpatores" paraphyly as follows: (Cyphophthalmi (Eupnoi (Dyspnoi + Laniatores))). Resolution within the Eupnoi, Dyspnoi, and Laniatores (the latter two united as Dyspnolaniatores nov.) is also stable to the superfamily level, permitting a new classification system for the Opiliones.  相似文献   

2.
The phylogenetic relationships among the main evolutionary lines of the arachnid order Opiliones were investigated by means of molecular (complete 18S rDNA and the D3 region of the 28S rDNA genes) and morphological data sets. Equally and differentially weighted parsimony analyses of independent and combined data sets provide evidence for the monophyly of the Opiliones. In all the analyses, the internal relationships of the group coincide in the monophyly of the following main groups: Cyphophthalmi, Eupnoi Palpatores, Dyspnoi Palpatores, and Laniatores. The Cyphophthalmi are monophyletic and sister to a clade that includes all the remaining opilionid taxa (=Phalangida). Within the Phalangida the most supported hypothesis suggests that Palpatores are paraphyletic, as follows: (Eupnoi (Dyspnoi + Laniatores)), but the alternative hypothesis (Laniatores (Eupnoi + Dyspnoi)) is more parsimonious in some molecular data analyses. Relationships within the four main clades are also addressed. Evolution of some morphological characters is discussed, and plesiomorphic states of these characters are evaluated using molecular data outgroup polarization. Finally, Martens' hypothesis of opilionid evolution is assessed in relation to our results.  相似文献   

3.
The morphological diversity of locomotor appendages in Arachnida is surveyed lo reconstruct phylogenetic relationships and discover evolutionary trends in form and function. The appendicular skeleton and musculature of representatives from the ten living arachnid orders ate described, and a system of homology is proposed. Character polarities are established through comparison with an outgroup. Limulus polyphemus Xiphosura). Cladistic analysis suggests that Arachnida is monophyletic and that absence of extensor muscles is a primitive condition. Extensors are primitively absent in Araneae. Amblypygi, Uropygi, Palpigradi, Ricinulei and Acari. Most similarities in the appendages of these orders are symplesiomorphic so that phylogenetic relationships among the 'extensorless' groups cannot be resolved solely on the basis of appendicular characters. Extensor muscles appear to have evolved once, and their presence is considered a synapomorphic feature of Opiliones, Scorpiones, Pseudoscorpiones and Solifugae. Solifugae lack extensors, but a parsimonious interpretation of other characters indicates that this is a secondary, derived condition. The phylogenetic relationships among these four orders are clarified by modifications of the patellotibial joint. Cladistic analysis indicates that Opiliones may be the sister group of the other three orders and that Scorpiones is the sister group of Pseudoscorpiones and Solifugae. Conclusions concerning phylogenetic relationships and evolutionary morphology presented here differ substantially from those of earlier studies on the locomotor appendages of Arachnida.  相似文献   

4.
Fissiphalliidae, a new family of the Opiliones suborder Laniatores, is described in the superfamily Gonyleptoidea, based on a new genus (Fissiphallius n. gen.) und 3 new species (F. sturmi n. sp., F. spinulatus n. sp., F. sympatricus n. sp.) from Colombia. Most emphasized are the male genitalic characters, unique in Opiliones: A honzontally split truncus which results in a long movable (glans) and an immovable finger (distal part of the truncus). Both hide the extremely long stylus with the seminal opening at its end. In an expanded state, the movable finger is bent dorsally by an erectile vesicle. It is shown that male genitalic characters in Opiliones display clear functional and constructional traits on the family level. Those characters, if used appropriately, will demonstrate that several families in gonyleptoid Laniatores are polyphyletic and should be divided into several taxa of the family level.  相似文献   

5.
6.
Caecilian morphology is strongly modified in association with their fossorial mode of life. Currently phylogenetic analyses of characters drawn from the morphology of caecilians lack resolution, as well as complementarity, with results of phylogenetic analyses that employ molecular data. Stemming from the hypothesis derived from the mammal literature that the braincase has the greatest potential (in comparison to other cranial units) to yield phylogenetic information, the braincase and intimately associated stapes of 27 species (23 genera) of extant caecilians were examined using images assembled via microcomputed tomography. Thirty‐four new morphological characters pertaining to the braincase and stapes were identified and tested for congruence with previously recognized morphological characters. The results reveal that when added to previous character matrices, characters of the braincase and stapes resolve generic‐level relationships in a way that is largely congruent with the results of molecular analyses. Analysis of a combined data set of molecular and morphological data provides a framework for conducting ancestral character state reconstructions, which resulted in the identification of 95 new synapomorphies for various clades and taxa, 27 of which appear to be unique for the taxa that possess them. Together these data demonstrate the utility of the application of characters of the braincase and stapes for resolving phylogenetic relationships for a group whose morphology is largely confounded by functional modifications. In addition this study provides evidence of the utility of the braincase in resolving problematic morphology‐based phylogeny outside of Amniota, in an amphibian group. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166 , 160–201.  相似文献   

7.
Phylogenetic relationships among major rodent superfamilies traditionally have been difficult to establish because of the apparent high level of convergence and parallelism seen among morphological characters and/or rapid differentiation of rodent groups in the Paleocene/Eocene. Nucleotide sequence data from the mitochondrial 12S rRNA gene were used to clarify phylogenetic relationships among the major groups of rodents as defined by Brandt (1855) and Tullberg (1899). Based on the approximately 800 bp analyzed for the 12S rRNA gene in 59 mammalian species, including 25 of the 32 extant rodent families, the major rodent groups that could be defined as monophyletic clades were the Hystricognathi, the Muroidea, and the Geomyoidea. In addition, support for superfamilial sister-group relationships was found for Aplodontoidea with Sciuroidea and Dipodoidea with Muroidea.  相似文献   

8.
The internal phylogeny of the arachnid order Opiliones is investigated by including molecular data from five molecular markers for ca. 140 species totalling 43 families of Opiliones. The phylogenetic analyses consisted of a direct optimization (DO) approach using POY v. 4 and sophisticated tree search algorithms as well as a static alignment analysed under maximum likelihood. The four Opiliones suborders were well‐supported clades, but subordinal relationships did not receive support in the DO analysis, with the exception of the monophyly of Palpatores (=Eupnoi + Dyspnoi). Maximum‐likelihood analysis strongly supported the traditional relationship of Phalangida and Palpatores: (Cyphophthalmi ((Eupnoi + Dyspnoi) Laniatores)). Relationships within each suborder are well resolved and largely congruent between direct optimization and maximum‐likelihood approaches. Age estimates for the main Opiliones lineages suggest a Carboniferous diversification of Cyphophthalmi, while its sister group, Phalangida, diversified in the Early Devonian. Diversification of all suborders predates the Triassic, and most major lineages predate the Cretaceous. The following taxonomic changes are proposed. Dyspnoi: Hesperonemastoma is transferred to Sabaconidae. Insidiatores: Sclerobunidae stat. nov. is erected as a family for Zuma acuta. © The Willi Hennig Society 2009.  相似文献   

9.
Abstract. Because the taxonomy of marine sponges is based primarily on morphological characters that can display a high degree of phenotypic plasticity, current classifications may not always reflect evolutionary relationships. To assess phylogenetic relationships among sponges in the order Verongida, we examined 11 verongid species, representing six genera and four families. We compared the utility of morphological and molecular data in verongid sponge systematics by comparing a phylogeny constructed from a morphological character matrix with a phylogeny based on nuclear ribosomal DNA sequences. The morphological phylogeny was not well resolved below the ordinal level, likely hindered by the paucity of characters available for analysis, and the potential plasticity of these characters. The molecular phylogeny was well resolved and robust from the ordinal to the species level. We also examined the morphology of spongin fibers to assess their reliability in verongid sponge taxonomy. Fiber diameter and pith content were highly variable within and among species. Despite this variability, spongin fiber comparisons were useful at lower taxonomic levels (i.e., among congeneric species); however, these characters are potentially homoplasic at higher taxonomic levels (i.e., between families). Our molecular data provide good support for the current classification of verongid sponges, but suggest a re-examination and potential reclassification of the genera Aiolochroia and Pseudoceratina . The placements of these genera highlight two current issues in morphology-based sponge taxonomy: intermediate character states and undetermined character polarity.  相似文献   

10.
The phylogenetic position of the Turnicidae (Aves) was unresolved. Historically, they were classified as members of the Struthioniformes, Galliformes, Charadriiformes, Columbiformes or the Gruiformes. In these classifications they had taxonomic rank of order 'Turniciformes' or family 'Turnicidae'. However, most of these studies followed phenetic methodology and used morphological similarity of taxa and plesiomorphic characters to classify Turnix . Recent phylogenetic studies on the basis of morphological character analyses or phenetic comparisons based on DNA-DNA hybridization experiments failed to clarify the phylogenetic realtionship of Turnix and suggested a position as 'incerte sedis', either among the Gruiformes or as the parvclass 'Turnicac'as a sistergroup to the 'Neoaves'.
We studied skeletal and myological material of Turnix to resolve its phylogenetic position. Further, we considered all characters that were previously discussed in literature to classify Turnix and tested them for their potential use in phylogenetic analysis. We added several yet unemployed morphological characters of phylogenetic significance to the analysis. The Struthioniformes, 'Galloanseres', and Columbiformes are each characterized by a clear set of autapomorpies. Only one autapomorphy in known for the Gruiformes but this character is of satisfying consistency and can be found in all families of the Gruiformes (Gruidae, Psophiidae, Aramidae. Rallidae) and Turnix. Turnix and the Rallidae share four complex morphological characters implying a close phylogenetic relationship. The data presented in this paper support the hypothesis that Turnix is a member of the Gruiformes with close relationships to the Rallidae. No evidence was found that would support a parvclass 'Turnicae'as sistergroup to the 'Neoaves'.  相似文献   

11.
Nawrocki, A. M., Schuchert, P. & Cartwright, P. (2009). Phylogenetics and evolution of Capitata (Cnidaria: Hydrozoa), and the systematics of Corynidae.—Zoologica Scripta, 39, 290–304. Generic‐ and family level classifications in Hydrozoa have been historically problematic due to limited morphological characters for phylogenetic analyses and thus taxonomy, as well as disagreement over the relative importance of polyp vs. medusa characters. Within the recently redefined suborder Capitata (Cnidaria: Hydrozoa: Hydroidolina), which includes 15 families and almost 200 valid species, family level relationships based on morphology alone have proven elusive, and there exist numerous conflicting proposals for the relationships of component species. Relationships within the speciose capitate family Corynidae also remain uncertain, for similar reasons. Here, we combine mitochondrial 16S, and nuclear 18S and 28S sequences from capitate hydrozoans representing 12 of the 15 valid capitate families, to examine family level relationships within Capitata. We further sample densely within Corynidae to investigate the validity of several generic‐level classification schemes that rely heavily on the presence/absence of a medusa, a character that has been questioned for its utility in generic‐level classification. We recover largely congruent tree topologies from all three markers, with 28S and the combined dataset providing the most resolution. Our study confirms the monophyly of the redefined Capitata, and provides resolution for family level relationships of most sampled families within the suborder. These analyses reveal Corynidae as paraphyletic and suggest that the limits of the family have been underestimated. Our results contradict all available generic‐level classification schemes for Corynidae. As classification schemes for this family have been largely based on reproductive characters such as the presence/absence of a medusa, our results suggest that these are not valid generic‐level characters for the clade. We suggest a new taxonomic structure for the lineage that includes all members of the newly redefined Corynidae, based on molecular and morphological synapomorphies for recovered clades within the group.  相似文献   

12.
We examined the phylogenetic relationships between species and genera within the caddisfly subfamily Drusinae (Trichoptera: Limnephilidae) using sequence data from two mitochondrial loci (cytochrome oxidase 1, large subunit rRNA) and one nuclear gene (wingless). Sequence data were analysed for 28 species from five genera from the subfamily. We analysed individual and combined data sets using a Bayesian Markov Chain Monte Carlo and a maximum parsimony approach and compared the performance of each partition for resolving phylogenetic relationships at this level. In terms of resolution and phylogenetic utility wingless outperformed the two mitochondrial gene partitions. Using both Shimodaira-Hasegawa and expected likelihood weights tests we tested several hypotheses of relationships previously inferred based on adult morphological characters. The data did not support the generic concept, or many previously proposed species groupings, based on adult morphology. In contrast, the molecular data correlated with the morphology and feeding ecology of larvae. Using Bayesian ancestral character state reconstructions we inferred the evolution of feeding ecology and relevant larval morphological characters. Our analyses showed that within the subfamily Drusinae two derived feeding types evolved. One of these--grazing epilithic algae--is otherwise unusual in the Limnephilidae and may have promoted the high degree of diversity in the Drusinae.  相似文献   

13.
Of the basal clades of extant birds (Neornithes) the 'landfowl' or galliforms (Aves, Galliformes) are the most speciose. Cladistic analysis of more than 100 morphological characters coded at the generic level for most putative galliform genera confirms that the megapodes ('mound builders'; Megapodiidae) are the most basal clade within the order. They are followed successively by the curassows, guans and chachalacas (Cracidae), which comprise the sister-group to all other extant Galliformes (i.e. Phasianoidea). Within this large 'phasianoid' clade, analyses suggest that the guineafowl (Numididae) are the most basal taxon, although monophyly of this 'family' is not strictly supported on the basis of the morphological characters employed. An additional major clade within the phasianoid Galliformes is recovered by this analysis, comprising the traditional groupings of New World quails (Odontophoridae) and Old World quails ('Perdicini'), yet only monophyly of the former is supported unambiguously by morphological characters. Relationships within the remainder of the phasianoid taxa, including the grouse (Tetraonidae), turkeys (i.e. Meleagris / Agriocharus spp.) as well as other 'pavonine' galliforms (i.e. peafowl; Pavo , Afropavo , Rheinardia , Argusianus and Polyplectron spp.) remain largely unresolved on the basis of morphological characters, yet monophyly of the major subdivisions is supported here. Although there are a number of important differences, especially with regard to relationships within the nonquail phasianoids, the results of this morphological phylogenetic (cladistic) analysis are broadly congruent both with traditional classifications and existing molecular hypotheses of galliform phylogenetic relationships.  相似文献   

14.
We explore the phylogenetic relationships of fantails (Aves: Rhipiduridae) using molecular characters derived from two nuclear introns and two mitochondrial genes. Our results indicate that Rhipidura hypoxantha is not a true fantail, but rather a member of the Stenostiridae clade that is morphologically and behaviourally convergent with fantails. Within the true Rhipiduridae, we identified six distinct clades; however, phylogenetic relationships among these groups were unresolved. The only well-supported sister relationship was between members of the grey and the rufous fantail complexes. Clades recovered through our model-based phylogenetic analyses generally correspond to previously proposed fantail complexes based on morphological characters. The phylogenetic position of R. atra and R. diluta remain unclear, as sister relationships varied between analyses for the prior whereas the latter was placed as sister to the New Guinea thicket fantails, R. leucothorax and R. threnothorax ; yet significant node support was not recovered for either taxa. Biogeographically, fantails appear to have radiated rapidly and the six clades are not geographically restricted, but instead span South-east Asia, New Guinea, Australia and Pacific Islands.  相似文献   

15.
External morphological characters are the basis of our understanding of diversity and species relationships in many darter clades. The past decade has seen the publication of many studies utilizing mtDNA sequence data to investigate darter phylogenetics, but only recently have nuclear genes been used to investigate darter relationships. Despite a long tradition of use in darter systematics few studies have examined the phylogenetic utility of external morphological characters in estimating relationships among species in darter clades. We present DNA sequence data from the mitochondrial cytochrome b (cytb) gene, the nuclear encoded S7 intron 1, and discretely coded external morphological characters for all 20 species in the darter clade Nothonotus. Bayesian phylogenetic analyses result in phylogenies that are in broad agreement with previous studies. The cytb gene tree is well resolved, while the nuclear S7 gene tree lacks phylogenetic resolution, node support, and is characterized by a lack of reciprocal monophyly for many of the Nothonotus species. The phylogenies resulting from analysis of the morphological dataset lack resolution, but nodes present are found in the cytb and S7 gene trees. The highest resolution and node support is found in the Bayesian combined data phylogeny. Based on our results we propose continued exploration of the phylogenetic utility of external morphological characters in other darter clades. Given the extensive lack of reciprocal monophyly of species observed in the S7 gene tree we predict that nuclear gene sequences may have limited utility in intraspecific phylogeographic studies of Nothonotus darters.  相似文献   

16.
Previous phylogenetic analyses of the tribe Phyllotini, one of the largest components of the subfamily Sigmodontinae, have been based on a single source of evidence. In particular, morphological analyses were largely based on craniodental data, almost neglecting the potential phylogenetic information present in the postcranium. Despite the significant advances made in relation to the knowledge of phyllotine phylogeny in recent times, there are several unsolved issues that highlight the importance of a phylogenetic analysis that integrates multiple sources of evidence, including previously considered sources as well as new sources of data. We present here the first combined phylogenetic analysis (morphological and molecular) of phyllotines, which includes the widest taxon and character sampling to date. Our dataset includes 164 morphological characters, of which 83 are postcranial characters, plus 3561 molecular characters, scored for 52 species from 34 genera of Oryzomyalia. In this study 75 postcranial characters not previously considered in this group are thoroughly described, and their utility for solving the relationships within Phyllotini is evaluated by means of different complementary analyses. Phyllotini was retrieved as a monophyletic clade in the combined analysis, with a composition that matches that obtained in most other recent analyses. All genera of phyllotines were monophyletic and show high support values. Abrotrichini, Akodontini and Oryzomyini were also monophyletic. The inclusion of postcranial data appears to be of limited utility to solve the phylogenetic relationships within Phyllotini.  相似文献   

17.
Laticifers and the classification of Euphorbia: the chemotaxonomy of Euphorbia esula L. Articulated and non-articulated laticifer cells represent distinctive cell types of relatively recent origin and occur in only a few families. Both types are of separate phylogenetic origin, reflecting independent evolutionary trends in the Euphorbiaceae. Supra-generic groupings of this family can be segregated into three taxonomic units using the laticifer character; with either articulated laticifers, non-articulated laticifers, or no laticifers. Such units may reflect more natural assemblages than now represented in the classification of this family. Laticifers possess chemical and morphological features of potential application as taxonomic characters to aid in delimiting species and interpreting evolutionary trends. The triterpenoid profile from latex of Euphorbia species has been shown to be diagnostic for a taxon. The qualitative and quantitative composition show a high level of stability under diverse environmental and physiological conditions indicating a genetic basis for triterpenoid synthesis. Triterpenoid profiles of known accessions of European E. esula L. and related presumptive taxa from North America readily separated them into distinctive chemotaxa that include one for E. esula L., whereas morphological features were found inadequate for separating accessions to presumptive taxa. Identification of adventive spurges in North America requires diagnostic analyses of Eurasian leafy spurges for comparison. Laticifer characters used in conjunction with relevant morphological features will provide a broadened insight into phylogenetic relationships with the Euphorbiaceae.  相似文献   

18.
The phylogenetic relationships of the Amphitritinae (Polychaeta: Terebellidae) were studied using parsimony analysis of 22 external morphological characters. To choose outgroups to polarize the characters, I carried out a preliminary analysis of the relationships of the four terebellid subfamilies and the Trichobranchidae. The single most parsimonious tree from the analysis supports monophyly of the Terebellidae by the presence of ventral glandular shields. However, this character is homoplasious within the Terebellomorpha, and further evaluation of the Terebellidae is recommended. Artacama and Thelepus were chosen as outgroups for the analysis of amphitritine genera. The generic level analysis yielded seven equally parsimonious trees, which are consistent in their topologies except for the relationships among seven genera in one large clade. In all trees, Artacama is the sister taxon to a large clade within the Amphitritinae; the Artacaminae is therefore synonymized with the Amphitritinae, which is diagnosed by the presence of double rows of uncini. Within the Amphitritinae, the status of several monotypic genera is questioned; plesiomorphic character states indicated by the analysis are discussed. The results presented are offered as working hypotheses of the relationships among amphitritine genera. The large number of homoplasies indicated by the analysis emphasizes the need to further evaluate these hypotheses using additional characters. With a robust phylogenetic hypothesis of amphitritine relationships, a re-classification of the group based on apomorphic character states can be undertaken, and questions regarding the evolution of morphological characters, reproductive modes, or biogeographical patterns can be properly addressed.  相似文献   

19.
Annelid relationships are controversial, and molecular and morphological analyses provide incongruent estimates. Character loss is identified as a major confounding factor for phylogenetic analyses based on morphological data. A direct approach and an indirect approach for the identification of character loss are discussed. Character loss can frequently be found within annelids and examples of the loss of typical annelid characters, like chaetae, nuchal organs, coelomic cavities and other features, are given. A loss of segmentation is suggested for Sipuncula and Echiura; both are supported as annelid ingroups in molecular phylogenetic analyses. Moreover, character loss can be caused by some modes of heterochronic evolution (paedomorphosis) and, as shown for orbiniid and arenicolid polychaetes, paedomorphic taxa might be misplaced in phylogenies derived from morphology. Different approaches for dealing with character loss in cladistic analyses are discussed. Application of asymmetrical character state transformation costs or usage of a dynamic homology framework represents promising approaches. Identifying character loss prior to a phylogenetic analysis will help to refine morphological data matrices and improve phylogenetic analyses of annelid relationships.  相似文献   

20.
Although 11 studies have addressed the systematics of the four families and 281 fish species of the ecomorphologically diverse Anostomoidea, none has proposed a global hypothesis of relationships. We synthesized these studies to yield a supermatrix with 463 morphological characters among 174 ingroup species, and inferred phylogeny with parsimony and Bayesian optimization. We evaluated the applicability of the supermatrix approach to morphological datasets, tested its sensitivity to missing data, determined the impact of homoplastic characters on phylogenetic resolution, and determined the distribution of homologies and homoplasies on the topology. Despite more than 60% missing data, analyses supported the monophyly of all families, and phylogenetic structure degraded only with inclusion of species with high percentages of missing data and in analyses limited to homoplasies. The latter differs modestly from the full matrix indicating phylogenetic signal in homoplastic characters. Character distributions differ across the phylogeny, with a greater prevalence of homologies at deeper nodes and homoplasies nearer the tips than expected by chance. This may suggest early diversification into distinct bauplans with subsequent diversification of faster evolving character systems. The morphological supermatrix approach is powerful and allows integration of classical data with modern methods to examine the evolution of multiple character systems.  相似文献   

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