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Morphological Data Matrices (morphological + data_matrix)
Selected AbstractsUltrastructure of spermiogenesis in the Cottonmouth, Agkistrodon piscivorus (Squamata: Viperidae: Crotalinae)JOURNAL OF MORPHOLOGY, Issue 3 2010Kevin M. Gribbins Abstract To date multiple studies exist that examine the morphology of spermatozoa. However, there are limited numbers of data detailing the ontogenic characters of spermiogenesis within squamates. Testicular tissues were collected from Cottonmouths (Agkistrodon piscivorus) and tissues from spermiogenically active months were analyzed ultrastructurally to detail the cellular changes that occur during spermiogenesis. The major events of spermiogenesis (acrosome formation, nuclear elongation/DNA condensation, and flagellar development) resemble that of other squamates; however, specific ultrastructural differences can be observed between Cottonmouths and other squamates studied to date. During acrosome formation vesicles from the Golgi apparatus fuse at the apical surface of the nuclear membrane prior to making nuclear contact. At this stage, the acrosome granule can be observed in a centralized location within the vesicle. As elongation commences the acrosome complex becomes highly compartmentalized and migrates laterally along the nucleus. Parallel and circum-cylindrical microtubules (components of the manchette) are observed with parallel microtubules outnumbering the circum-cylindrical microtubules. Flagella, displaying the conserved 9 + 2 microtubule arrangement, sit in nuclear fossae that have electron lucent shoulders juxtaposed on either side of the spermatids basal plates. This study aims to provide developmental characters for squamates in the subfamily Crotalinae, family Viperidae, which may be useful for histopathological studies on spermatogenesis in semi-aquatic species exposed to pesticides. Furthermore, these data in the near future may provide morphological characters for spermiogenesis that can be added to morphological data matrices that may be used in phylogenetic analyses. J. Morphol. 2010. © 2009 Wiley-Liss, Inc. [source] The role of character loss in phylogenetic reconstruction as exemplified for the AnnelidaJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 4 2007C. Bleidorn Abstract 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. Zusammenfassung Die Phylogenie der Annelida wird nach wie vor kontrovers diskutiert und morphologische und molekulare Analysen liefern hierbei unterschiedliche Ergebnisse. Merkmalsverluste können phylogenetische Analysen morphologischer Daten in die Irre führen. In der vorliegenden Arbeit werden ein direkter und ein indirekter Ansatz zur Erkennung von Merkmalsverlusten vorgestellt. Es wird gezeigt, dass Merkmalsverlust innerhalb der Anneliden häufig auftritt und das hiervon auch typische Annelidenmerkmale, wie z.B Borsten, Nuchalorgane oder Coelomräume betroffen seien können. Molekularphylogenetische Analysen unterstützen eine Stellung der Echiura und Sipuncula innerhalb der Anneliden und somit ist für diese Taxa ein Verlust der Segmentierung anzunehmen. Es wird demonstriert, dass Merkmalsverlust durch herterochrone Evolution verursacht werden kann. Am Beispiel von Orbiniiden und Arenicoliden wird gezeigt, wie paedomorphe Taxa in kladistischen Analysen morphologischer Daten falsch platziert werden. Verschiedene Ansätze zum Umgang mit Merkmalsverlust in morphologischen Datensätzen werden präsentiert und diskutiert. Hierbei stellen die Verwendung asymmetrischer Merkmalstransformationskosten oder die Verwendung dynamischer Homologiehypothesen aussichtsreiche Ansätze dar. Jedoch werden für alle Ansätze Phylogeniehypothesen benötigt, die in einer Analyse unabhängiger Daten (bspw. Moleküle) erstellt wurden, um Merkmalsverluste sicher zu identifizieren. [source] Gnathostomulid phylogeny inferred from a combined approach of four molecular loci and morphologyCLADISTICS, Issue 1 2006Martin V. Sørensen The phylogeny of the obscure metazoan phylum Gnathostomulida has previously only been addressed with cladistic analyses of morphological data. In the present study DNA sequence data from four molecular loci, including 18S rRNA, 28S rRNA, histone H3 and cytochrome c oxidase subunit I, are added to a revised morphological data matrix. The data set represents 23 gnathostomulid species that are analyzed under direct optimization using parsimony as the optimality criterion. The results obtained from analyzing the four molecular loci and combined morphological and molecular data under different parameter sets are generally very congruent, and differ only on minor points. The results clearly support gnathostomulid monophyly, as well as the basal division of Gnathostomulida into Filospermoidea and Bursovaginoidea. Filospermoidea were represented by species of Haplognathia and Cosmognathia, and generic monophyly is supported for both groups. Within Bursovaginoidea, Conophoralia (= Austrognathiidae) and Scleroperalia appear as sister groups. Monophyly of Mesognathariidae was confirmed as well, whereas the relationships between species of Gnathostomulidae and Onychognathiidae were contradicted by the molecular data when compared to morphological observations. ©The Willi Hennig Society 2006. [source] Phylogeny and Systematic Position of Opiliones: A Combined Analysis of Chelicerate Relationships Using Morphological and Molecular Data,CLADISTICS, Issue 1 2002Gonzalo Giribet 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. 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