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Phylogenetic Significance (phylogenetic + significance)
Selected AbstractsA NEW TEREBRATULID BRACHIOPOD SPECIES FROM THE SIEGENIAN OF THE DRA VALLEY, MOROCCO, AND ITS STRATIGRAPHIC, PALAEOGEOGRAPHIC AND PHYLOGENETIC SIGNIFICANCEPALAEONTOLOGY, Issue 4 2008MENA SCHEMM-GREGORY Abstract:, A new terebratulid brachiopod species, Rhenorensselaeria jansenii, has been identified in the Merzâ-Akhsaï Formation of the Dra Valley, Morocco, and the Grauwacke de Montguyon of the Amorican Massif, France. It is compared with the other known species of Rhenorensselaeria from Europe, Rh. strigiceps and Rh. demerathia, as well as with Rh. macgerriglei from North America, from which it differs in being larger and having coarser costae. Its possible life habit in clusters and its fossil community are compared with those of Rh. strigiceps from the Rheinisches Schiefergebirge (,Rhenish Slate Mountains'), Germany, which it most resembles. A new phylogeny of the subfamily Rhenorensselaerinae is constructed. The close phylogenetic relationship between Rh. jansenii and Rh. strigiceps confirms close palaeobiogeographical relationships between North Africa, France and the Rheinisches Schiefergebirge as well as a wider relationship between Central Europe and Gaspé, eastern Canada, during the Early Devonian. Taxa of Rhenorensselaeria are mainly restricted to the Middle and Upper Siegenian, although rare individuals have been found in the Lower Emsian of Central Europe and North America. Because of their abundance in the Dra Valley and Rheinisches Schiefergebirge and their short life span, rhenorensselaerid taxa can be regarded as important stratigraphical markers of Middle,Late Siegenian and Early Emsian sediments in North Africa and Central Europe. [source] Sperm ultrastructure and spermiogenesis in two Exogone species (Polychaeta, Syllidae, Exogoninae)INVERTEBRATE BIOLOGY, Issue 4 2002Adriana Giangrande The spermatozoa of Exogone naidina and E. dispar are characterized by a prominent bell-shaped acrosome, a spheroidal nucleus, and a conventional flagellum. During spermiogenesis, the acrosomal vesicle undergoes conspicuous modifications leading to its final bell shape with a posterior opening. The subacrosomal material initially shows radiating filaments but in mature sperms it appears as a meshwork of electron-opaque material. The acrosomal axis is oblique with respect to the main longitudinal sperm axis. The chromatin is arranged in electron-opaque strands in the early spermatids, then becomes amorphous, and is finally organized in filaments in mature sperms. Centrioles are orthogonally arranged beneath the nucleus and fibers radiate from the distal centriole to contact the plasma membrane and the single mitochondrion. The latter is located eccentrically on the side of the nucleus opposite the acrosome. A disk-shaped structure is evident beneath the distal centriole. The flagellar axoneme has a 9+2 microtubule pattern. A conspicuous glycocalyx surrounds the flagellar plasma membrane, and an electron-lucent space is present between these two structures at the distal tip of the flagellum. We compare the sperm morphology of these two species of Exogone with that described in other members of the subfamily Exogoninae. The fine structure of these two species supports the occurrence of an ent-aquasperm type within Exogoninae, in accordance with the brood strategy present within this subfamily. The mode of reproduction is of taxonomic importance for defining subfamilies within Syllidae, and is likely also of phylogenetic significance. Because epitoky is probably plesiomorphic, the ent-aquasperm type found in Exogoninae can be considered a derived feature within Syllidae. [source] Ultrastructure and development of forked and capillary setae in the polychaetes Orbinia bioreti and Orbinia latreillii (Annelida: Orbiniidae)INVERTEBRATE BIOLOGY, Issue 1 2001Bilke Hausam Abstract. Recent investigations into chaetogenesis of certain types of annelid setae provide important results for unravelling the phylogenetic relationships within several taxa of poly-chaetous annelids. This paper presents data on ultrastructure and development of 2 types of orbiniid setae. The analysis of the crenulate capillaries in Orbinia latreillii reveals a formation process which clearly differs from the development of Equisetum -like setae of lingulid bra-chiopods. For the investigation of forked setae, which up to now have been neglected in the discussion on the phylogenetic significance of annelid setae, notopodial setal sacs of O. latreillii and O. bioreti were studied by light- and electron microscopy. In the setal sacs, stages of forked setae are restricted to a dorsocaudal pouch, which represents the site of setal formation. The 2 diverging, stout tines of the fork bear spines on their inner margins, each of which is preformed by a single microvillus. After retraction of the microvilli, a characteristic pattern of the setal canals inside of the spines remains. The present study belongs to a series of comparative studies into chaetogenesis of forked setae. These special setae are also found in other orbiniid taxa as well as some paraonids, scalibregmatids, and nephtyids. Ultrastructural investigations into the development of these forked setae might suggest homology. [source] Three-dimensional reconstruction of the odontophoral cartilages of Caenogastropoda (Mollusca: Gastropoda) using micro-CT: Morphology and phylogenetic significanceJOURNAL OF MORPHOLOGY, Issue 5 2009Rosemary E. Golding Abstract Odontophoral cartilages are located in the molluscan buccal mass and support the movement of the radula during feeding. The structural diversity of odontophoral cartilages is currently known only from limited taxa, but this information is important for interpreting phylogeny and for understanding the biomechanical operation of the buccal mass. Caenogastropods exhibit a wide variety of feeding strategies, but there is little comparative information on cartilage morphology within this group. The morphology of caenogastropod odontophoral cartilages is currently known only from dissection and histology, although preliminary results suggest that they may be structurally diverse. A comparative morphological survey of 18 caenogastropods and three noncaenogastropods has been conducted, sampling most major caenogastropod superfamilies. Three-dimensional models of the odontophoral cartilages were generated using X-ray microscopy (micro-CT) and reconstruction by image segmentation. Considerable morphological diversity of the odontophoral cartilages was found within Caenogastropoda, including the presence of thin cartilaginous appendages, asymmetrically overlapping cartilages, and reflexed cartilage margins. Many basal caenogastropod taxa possess previously unidentified cartilaginous support structures below the radula (subradular cartilages), which may be homologous to the dorsal cartilages of other gastropods. As subradular cartilages were absent in carnivorous caenogastropods, adaptation to trophic specialization is likely. However, incongruence with specific feeding strategies or body size suggests that the morphology of odontophoral cartilages is constrained by phylogeny, representing a new source of morphological characters to improve the phylogenetic resolution of this group. J. Morphol. 2009. © 2008 Wiley-Liss, Inc. [source] The peristomatic structures of Lithobiomorpha (Myriapoda, Chilopoda): Comparative morphology and phylogenetic significanceJOURNAL OF MORPHOLOGY, Issue 2 2008Markus Koch Abstract A comparative survey of the epipharynx and hypopharynx of lithobiomorph centipedes by light and scanning electron microscopy examines 18 species that sample the major groups of both families, the Lithobiidae and Henicopidae. Cladistic analysis of 11 characters of the peristomatic structures together with 29 additional morphological characters serves as a basis for interpreting the evolution of the lithobiomorph peristomatic structures. Scutigeromorpha is used for outgroup comparison in the framework of a homology scheme for the basic components of the epi- and hypopharynx. Compared to other chilopods, the monophyly of Lithobiomorpha is supported by a row of distinctive bottle-shaped gland openings at the border between the labral and clypeal parts of the epipharynx, as well as by a distinctive shape of the hypopharynx. Paired rows of elongate spines on the clypeal part of the epipharynx are an apomorphic character of Lithobiidae. The transformation of these spine rows into a few groups of branching spines is characteristic for the Monotarsobius group sensu Verhoeff. Similar groups of branching clypeal spines characterize the Anopsobiinae within Henicopidae, whereas Henicopinae possess a dense cluster of short, simple spines instead. The recently described genus Dzhungaria is resolved closer to Henicopinae than to Anopsobiinae, a hypothesis supported by a field of grooves on the medial labral part of the epipharynx. Monophyly of Henicopidae does not receive unique support from the peristomatic structures although two homoplastic characters contribute to this node; among these, the reduction of a median spine field between clypeal and labral parts of the epipharynx to a narrow transverse band also supports a close relationship between the Ezembius group and Hessebius within Lithobiidae. An Ezembius + Hessebius clade is additionally supported by the absence of a transverse bulge between the clypeal and labral parts of the epipharynx, a character otherwise present in all lithobiomorph species studied so far. Lithobius is resolved as polyphyletic, with different species being most closely related to such genera as Australobius, Hessebius and Pleurolithobius. J. Morphol., 2008. © 2007 Wiley-Liss, Inc. [source] Opisthonotal glands in the Camisiidae (Acari, Oribatida): evidence for a regressive evolutionary trendJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 1 2009G. Raspotnig Abstract Paired, sac-like and typically large opisthonotal glands (syn. oil glands), mainly considered for chemical protection and communication, characterize the so-called ,glandulate Oribatida' which include the Parhyposomata, Mixonomata, Desmonomata and Brachypylina but also the Astigmata. Among these groups distinct evolutionary trends affect the morphology of glands and their secretion profiles, thereby rendering them highly informative characters with phylogenetic significance. One striking tendency, convergently occurring in a few glandulate groups, leads to the degeneration or even complete regression of opisthonotal glands. In this study, a first example of coherent evolutionary steps towards opisthonotal gland degeneration is described by using desmonomatan Camisiidae as a model: Opisthonotal glands in representatives of genus Platynothrus still show morphologically and chemically ancient conditions with fairly-well developed glandular reservoirs. Secretion patterns mainly consist of a characteristic set of terpenes and aromatics (,astigmatid compounds') as found in outgroups such as desmonomatan Trhypochthoniidae. Progressive states of regression of opisthonotal glands, along with a reduction of component-richness and amounts of secretions, occur in representatives of Heminothrus and, more conspicuously, in species of Camisia, most likely indicating a consistent evolutionary trend. This trend towards opisthonotal gland atrophy may be due to novel alternative and cheap strategies of passive defense in more-derivative camisiids , such as mechanical protection by encrustation of the cuticle , that possibly compensate for the lack of chemical defenses. Zusammenfassung Paarige, sackförmige und typischerweise große opisthosomatische Drüsen (syn. Öldrüsen), deren Sekrete hauptsächlich zum chemischen Schutz und zur Kommunikation dienen sollen, kennzeichnen die sogenannten glandulaten Hornmilben. Innerhalb dieser Hornmilbengruppe, die die Parhyposomata, Mixonomata, Desmonomata, Brachypylina, aber auch die astigmaten Milben umfasst, waren die Öldrüsen offensichtlich in morphologischer und chemischer Hinsicht deutlich unterschiedlichen evolutiven Trends unterworfen; damit sind Öldrüsen ein phylogenetisch außerordentlich wichtiger Merkmalskomplex in der Oribatiden-Systematik geworden. Eine auffällige Tendenz allerdings, die offensichtlich mehrmals konvergent auftritt, führt zur Rückbildung der Drüsen in bestimmten glandulaten Gruppen. In der vorliegenden Arbeit wird zum ersten Mal eine zusammenhängende Linie solcher Rückbildungsstadien am Beispiel der Camisiidae (Desmonomata) beschrieben: die weitgehend noch gut ausgebildeten Öldrüsen von Vertretern der Gattung Platynothrus zeigen morphologisch und chemisch ursprüngliche Merkmale. Sekretprofile bestehen hauptsächlich aus einem charakteristischen Set von Terpenen und Aromaten ("astigmatid compounds'), das auch in Außengruppen wie z.B. bei Trhypochthoniiden auftritt. Fortschreitende Stadien der Rückbildung von Öldrüsen, verbunden mit einer Verarmung der Sekretprofile und einer Verringerung an Sekretmengen, treten in Vertretern von Heminothrus und, noch auffälliger, bei verschiedenen Arten von Camisia auf: dieses Phänomen, übereinstimmend mit einem auf morphologischen Daten basierenden Systemvorschlag, wird als evolutiver Trend innerhalb der Camisiidae gedeutet. Dieser Trend zur Öldrüsenrückbildung ist möglicherweise mit einer alternativen Strategie passiver Verteidigung bei weiter abgeleiteten Camisiiden zu erklären, die Krustenbildungen aus Cerotegument und Bodenpartikeln auf der Körperöberfläche als mechanischen Schutz gegen Prädatoren nützen. Diese möglicherweise energetisch billige Variante könnte den Verlust chemischer Verteidigung über Öldrüsensekretion kompensieren. [source] Divided and undivided compound eyes in Ascalaphidae (Insecta, Neuroptera) and their functional and phylogenetic significanceJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 4 2006K. Fischer Abstract The external morphology of the compound eyes of 13 species of the Ascalaphidae family (Insecta, Neuroptera) from Africa, Asia and Europe was studied in relation to the habitat, phylogeny and time of activity during the day. The six species with undivided eyes (Haplogleniinae) are nocturnal; four inhabit more or less open terrain, while two inhabit more or less dense vegetation. Of the seven species with divided eyes (Ascalaphinae), three are diurnal, one is crepuscular and nocturnal, and three are nocturnal. It was found that two of the diurnal species inhabit open terrain and open forest, and one inhabits dense vegetation; the crepuscular and nocturnal species inhabits open terrain; and two of the nocturnal species inhabit open terrain, while one inhabits dense vegetation. The results are discussed in relation to the hypothesis that divided eyes evolved from undivided eyes, originally serving as an adaptation to daytime vision in open terrain. Zusammenfassung Bei 13 Arten aus der Familie der Ascalaphidae (Insecta, Neuroptera) aus Afrika, Asien und Europa wurde die externe Morphologie der Komplexaugen im Zusammenhang mit der tageszeitlichen Aktivität, dem Habitat und der Phylogenie untersucht. Alle sechs Arten mit ungeteilten Augen (Haplogleniinae) sind nachtaktiv. Vier kommen im mehr oder weniger offenen Gelände und zwei kommen in mehr oder weniger dichter Vegetation vor. Von den sieben Arten mit geteilten Augen (Ascalaphinae) sind drei tagaktiv, eine ist dämmerungs- und nachtaktiv und drei sind nachtaktiv. Zwei von den tagaktiven Arten kommen im offenen Gelände und in lichten Baumbeständen vor, eine Art bewohnt dichte Vegetation. Die dämmerungs- und nachtaktive Art kommt im offenen Gelände vor.Von den drei nachtaktiven Arten kommen zwei im offenen Gelände vor, eine bevorzugt dichte Vegetation. Die Ergebnisse werden im Zusammenhang mit der Hypothese diskutiert, dass sich im Verlauf der Evolution die geteilten Augen aus ungeteilten Augen entwickelt haben und ursprünglich eine Anpassung an das Sehen bei Tag im offenen Gelände darstellen. [source] The phylogenetic affinities of the Pondaung taliAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2010Marian Dagosto Abstract The phylogenetic affinities of the primates of the late middle Eocene Pondaung Formation of Myanmar have long been disputed. The discovery of the NMMP 39 talus (Marivaux et al.: Proc Natl Acad Sci USA 100 (2003) 13173,13178) provided the first clear evidence from the postcranium that a relatively large-bodied haplorhine primate is represented in the Pondaung fauna. Another talus (NMMP 82; Marivaux et al., 2010). Talar morphology, phylogenetic affinities and locomotor adaptation of a large-bodied amphipithecid primate from the late middle Eocene of Myanmar, Am J Phys Anthropol DOI: 10.1002/ajpa.21307) has been recently recovered which also pertains to Haplorhini. The metric and nonmetric features supporting the hypothesis of anthropoid affinities for NMMP 39 have been criticized by Gunnell and Ciochon (Gunnell GF, Ciochon RL. 2008. Revisiting primate postcrania from the Pondaung Formation of Myanmar. In: Fleagle JG, Gilbert CC, editors. Elwyn Simons: a search for origins. New York: Springer. p 211,228). Their analysis, however, was based on a very limited choice of variables, taxa, and individuals. Based on an extended sample, we are able to produce both principal components and discriminant functions that yield a rather clear separation of extant haplorhine and strepsirhine tali. Both principal components and discriminant function scores of the Pondaung tali fall with those of haplorhine primates. In addition, the Pondaung tali lack all the derived nonmetric features characteristic of strepsirhine primates, but exhibit all the features characteristic of haplorhine primates. We dispute the features Gunnell and Ciochon (2008) claim are uniquely shared by the Pondaung tali and adapiforms. Their rejection of the phylogenetic significance of the features shared by these tali and haplorhines is unwarranted by the evidence. Based on both metric and nonmetric features, the Pondaung tali are structurally most similar to the tali of haplorhines, particularly anthropoids. Am J Phys Anthropol 143:223,234, 2010. © 2010 Wiley-Liss, Inc. [source] The Phylogenetic Significance of Anthropoid Paranasal SinusesTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 11 2008James B. Rossie Abstract In this study, the phylogenetic significance of anthropoid paranasal sinus anatomy is explored. New information reported in recent years has precipitated new hypotheses of sinus homology and more than doubled the number of anthropoid genera for which confident assessments of sinus identity can be made. As a result, it is likely that the phylogenetic meaning of commonly cited characters such as the ethmoid and frontal sinuses will change. The traditional method of "character mapping" is employed to test hypotheses of sinus homology and to reconstruct the ancestral states for sinus characters in major anthropoid clades. Results show that most sinuses appear to be primitive retentions in anthropoids, with their absences in various genera representing losses. Accordingly, many of these sinuses are potential anthropoid synapomorphies. Anat Rec, 291:1485,1498, 2008. © 2008 Wiley-Liss, Inc. [source] Virtual study of the endocranial morphology of the matrix-filled cranium from Eliye Springs, KenyaTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 2 2004Günter Bräuer Abstract This paper provides the first endocranial description of the matrix-filled archaic Homo sapiens cranium from Eliye Springs, Kenya. Using CT-based 3D reconstruction, the virtually cleaned endocranial surface allowed for the assessment of more than 30 metrical and nonmetrical features, most of which are considered of phylogenetic importance. The VOXEL-MAN program used was most valuable in describing and analyzing the morphological conditions. Since many of the features have not been widely or virtually studied, a small sample of late Pleistocene/early Holocene skulls from East Africa was similarly analyzed for insight into recent variation. The comparisons between Eliye Springs and the modern African specimens showed that the endocranial morphology of this probably later Middle Pleistocene hominid falls into, or close to, the modern ranges of variation for most features. This study also addresses the problems of variation and phylogenetic significance of many of the features, and highlights the need for basic studies on the variability and relevance of such endocranial traits in human evolution. Anat Rec Part A 276A:113,133, 2004. © 2004 Wiley-Liss, Inc. [source] Cambrian Fossil Embryos from Western Hunan, South ChinaACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 3 2009Xiping DONG Abstract: The exquisitely preserved fossil embryos of Markuelia recovered from the limestones of the Middle Cambrian Haoqiao Formation and Upper Cambrian Bitiao formation in western Hunan, South China are described and illustrated in detail for the first time. A new species Markuelia elegans sp. nov. is established based mainly on embryos from the Upper Cambrian. A few of animal's resting eggs, which are comparable with those of the Ediacaran Doushantuo Formation, have been also found in the Upper Cambrian of western Hunan. The membrane of one egg from the uppermost Cambrian has been replaced by pyrite and the overgrowth of the pyrite crystals exhibits a unique inorganic pattern termed herein ,Pseudoembryo'. The taphonomic setting in deeper water with possible strong reducing conditions promoted the excellent preservation for the Markuelia specimens. The study of Markuelia provides not only constraint on the anatomy, affinity, embryonic development and phylogenetic significance of this wormlike animal and but also opens a new window onto the evolution and development of the earliest animals. [source] | |||||||||||||