124,978 research outputs found
From Cnidaria to Higher Metazoa in one step
No full textThe origin of multicellular animals and how multicellularity evolved is one of those difficult and delicate biological problems that has been pondered over for centuries. This book attempts to summarize some of the more recent results in phylogenetics and developmental biology that address the evolution of key innovations in metazoans. The book has three main sections. The first section contains five chapters that address the phylogenetic issues involving this part of the tree of life. Even though modern genome technology has made it possible to study these issues using a vast information database the elucidation of the relationships in this part of the tree of life continues to be elusive. The second section of the book addresses some of the more prominent questions concerning the developmental biology of metazoan evolution. The topics in this section focus on nervous system development, sensory organ development and developmental systems. The third section of the book focuses on the evolution of pattern and process in the incredible forms of life that we call Metazoa. The topics covered in this part of the book include the evolution of life histories, ecological associations and the evolution of biogeochmical aspects of metazoa. The book has over 40 illustrations and an up to date bibliography of over 500 references. Each chapter concludes with a set of questions for study and discussion to assist instructors and students in delving more deeply into the topics covered by the seventeen chapters in the book.
Table of Contents
Introduction: A Phylogenomic Journey Through the Animal Tree of Life: Key Innovations in the Evolution of Metazoa; B. Schierwater and R. DeSalle
Tangled Roots in the Animal Tree of Life
Putting Animals in their Place Within a Context of Eukaryotic Innovations; D. Vazquez, L. Wegener Parfrey and L.A. Katz
Elucidating Animal Phylogeny: Advances in Knowledge and Forthcoming Challenges; K.M. Kocot, J.T. Cannon and K.M. Halanych
Key Transitions in Animal Evolution: a Mitochondrial DNA Perspective; D.V. Lavrov
Pending Issues in Development and Phylogeny of Arthropods; J.S. Deutsch
The Earliest Animals: From Genes to Transitions
The Pre-nervous System and Beyond—Poriferan Milestones in the Early Evolution of the Metazoan Nervous System; M. Nickel
A Key Innovation in Evolution, the Emergence of Neurogenesis: Cellular and Molecular Cues from Cnidarian Nervous Systems; B. Galliot, M. Quiquand, M. Miljkovic-Licina and S. Chera
From Cnidaria to "Higher Metazoa" in One Step; F. Boero and S. Piraino
Basal Metazoan Sensory Evolution; D.K. Jacobs, D.A. Gold, N. Nakanishi, D. Yuan, A. Camara, S.A. Nichols and V. Hartenstein
Cnidarian Gene Expression Patterns and the Origins of Bilaterality—Are Cnidarians Reading the Same Game Plan as "Higher" Animals?; E.E. Ball, D.M. de Jong, B. Schierwater, C. Shinzato, D.C. Hayward and D.J. Miller
Key Transitions During Animal Phototransduction Evolution: Co-duplication as a Null Hypothesis for the Evolutionary Origins of Novel Traits; T.H. Oakley and D.C. Plachetzki
Vertebrate Hox Genes and Specializations in Mammals; C. Kappen
Pattern and Process at the Base of the Metazoan Tree of Life
Field Biology of Placozoans (Trichoplax): Distribution, Diversity, Biotic Interactions; V. Buchsbaum Pearse and O. Voigt
Trichoplax and Placozoa: One of the Crucial Keys to Understanding Metazoan Evolution; B. Schierwater et al.
A Food’s-Eye View of Animal Transitions; N.W. Blackstone
Lost in Transition: The Biogeochemical Context of Animal Origins; E. Gaidos
Redefining Stem Cells and Assembling Germ Plasm: Key Transitions in the Evolution of the Germ Line; J. Srouji and C. Extavour
Questions and Discussio
“Spirituality and Comics in Hugo Pratt, Alan Moore, and David B.: Esotericism as “unsettled knowledge”
No full textThis article describes the artistic production and intellectual and spiritual life of three of the most important artists in the field of comics and graphic novels: Hugo Pratt, Alan Moore, and David B. These artists share a common interest in esotericism: they have participated in esoteric and alternative spiritualitygroups,and in their artistic worksthey reproduce esoteric symbols, narratives, and doctrines.Scholars in religious studies have already described theconnectionsbetween contemporary art and esotericism, arguing that artists are “spiritual seekers”who representtheir spiritual quest.This articlegoes beyond such a perspective by describing how esotericism has changed in contemporary societies and,in particular,within the frame of comics and graphic novels.Esotericism is generally understood as a “rejected”, “absolute”, and “stigmatised” form of knowledge, characterisedby elitism andsecrecy.The esotericism of these artists (both in their life and in their artworks)is not “rejected”;on the contrary,it has become mainstream, with best-seller publications and museum exhibitions. Furthermore, it is not“absolute”or “hidden”;rather,it reveals doubt and deconstructs religion and spirituality, sometimeseven challengingor mockingthem. For these artists, esotericism is a form of “unsettled knowledge”, a never-ending quest for transcendenceanda means of learning about the unconsciousand humankind.It finds its legitimisation inreligious texts, revelations,and religious movements, but mainly in the power of storytelling. This article argues that the blurring between reality and narrationdoes not imply a process of disenchantment,nora“hyper-religion”, insteadrepresentinganother form of spirituality in contemporary societies. Finally, this“unsettled knowledge”is also unsettling for the reader, who is challenged by theseartworksandfinds in themwondrous, dazzling,and dreamlikeexperience
Spirituality and Comics in Hugo Pratt, Alan Moore, and David B.: Esotericism as “Unsettled Knowledge”*
No full textThis article describes the artistic production and intellectual and spiritual life of three of the most important artists in the field of comics and graphic novels: Hugo Pratt, Alan Moore, and David B. These artists share a common interest in esotericism: they have participated in esoteric and alternative spirituality groups, and in their artistic works they reproduce esoteric symbols, narratives, and doctrines. Scholars in religious studies have already described the connections between contemporary art and esotericism, arguing that artists are “spiritual seekers” who represent their spiritual quest. This article goes beyond such a perspective by describing how esotericism has changed in contemporary societies and, in particular, within the frame of comics and graphic novels. Esotericism is generally understood as a “rejected”, “absolute”, and “stigmatised” form of knowledge, characterised by elitism and secrecy. The esotericism of these artists (both in their life and in their artworks) is not “rejected”; on the contrary, it has become mainstream, with best-seller publications and museum exhibitions. Furthermore, it is not “absolute” or “hidden”; rather, it reveals doubt and deconstructs religion and spirituality, sometimes even challenging or mocking them. For these artists, esotericism is a form of “unsettled knowledge”, a never-ending quest for transcendence and a means of learning about the unconscious and humankind. It finds its legitimisation in religious texts, revelations, and religious movements, but mainly in the power of storytelling. This article argues that the blurring between reality and narration does not imply a process of disenchantment, nor a “hyper-religion”, instead representing another form of spirituality in contemporary societies. Finally, this “unsettled knowledge” is also unsettling for the reader, who is challenged by these artworks and finds in them wondrous, dazzling, and dreamlike experiences
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Cnidarian Milestones in Metazoan Evolution
No full textCnidarians display most of the characters considered as milestones of metazoan evolution. Whereas a tissuelevel organization was probably already present in the multicellular common ancestor of all animals, the Urmetazoa, the emergence of important animal features such as bilateral symmetry, triploblasty, a polarized nervous system, sense organs (eyes, statocysts), and a (chitinous or calcium-based) continuous skeleton can be traced back before the divergence between cnidarians and bilaterians. Modularity and metamery might be also regarded as two faces of the same medal, likely involving conserved molecular mechanisms ruling animal body architectures through regional specification of iterated units. Available evidence indicates that the common ancestor of cnidarians and bilaterians, the UrEumetazoa, was a surprisingly complex animal with nerve cell differentiation. We suggest that paedomorphic events in descendants of this ancestor led to the array of diversity seen in the main extant animal phyla. The use of molecular analyses and identifying the genetic determinants of anatomical organizations can provide an integrative test of hypotheses of homologies and independent evidence of the evolutionary relationships among extant taxa
Fossilization processes of graptolites: insights from the experimental decay of Rhabdopleura sp. (Pterobranchia)
No full textLaboratory experiments documenting the decomposition pattern of extant organisms are used to reconstruct the anatomy and taphonomy of fossil taxa. The subclass Graptolithina (Hemichordata: Pterobranchia) is a significant fossil taxon of the Palaeozoic era, represented by just one modern genus, Rhabdopleura. The rich graptolite fossil record is characterized by an almost total absence of fossil zooids. Here we investigated the temporal decay pattern of Rhabdopleura sp. tubes, stolons and single zooids removed from the tubarium. Tubes showed decay after four days, when fuselli began to separate from the tube walls. This rapid loss may explain the absence of fuselli from some graptolite fossils. The black stolon did not show decay until day 155. One day after their removal, zooids quickly decomposed in the following temporal sequence: (1) tentacles; (2) ectoderm; (3) arms; (4) gut; (5) cephalic shield, leading to complete disappearance of recognizable body parts in the majority of experimental zooids within 64–104 h. The most resistant zooid features to decay (61 days) were black-pigmented granules. These results indicate that tubes and the black stolon would persist for weeks across death, transport and burial, whereas a complete decay of zooid features occurs in few days, providing an explanation for the overall poor record of fossil graptolite zooids and suggesting that recorded silhouettes of fossil zooids may be attributed to fossil decay-resistant pigments
Eugymnanthea inquilina Palombi 1935
No full text<i>Eugymnanthea inquilina</i> Palombi, 1935 <p>Fig. 59 A, B</p> <p>See Kramp (1961) for a complete synonymy.</p> <p> <b>Material examined.</b> HCUS-S 0 66 (Hydrozoa Collection, University of Salento—fauna of the Salento Peninsula)—polyp stage.</p> <p> <b>Description</b> (based on our own observations; Palombi 1935; Kramp 1959; Kubota 1979, 1983):</p> <p> <b>Hydroid.</b> Epizootic on gills of bivalves, solitary or forming small colonies; hydranth tubular, without hydrothecae, with a conical hypostome; with a single whorl of 20–24 filiform tentacles; with an intertentacular membranous web, fixed to the host by a basal disc; often young hydranths budding from the middle part of the primary hydranth body; 1–2 medusa buds at the basal part of the hydranths. Colour: hydroid yellow-orange.</p> <p> <b>Habitat type and substrate.</b> Hydroid living in bivalve Mollusca such as <i>Ruditapes decussatus, Mytilus galloprovincialis</i> and others (Palombi 1935; Cerruti 1941 as <i>Mytilhydra polimantii</i>; Morri 1981a, b; Gili, 1986; Brinckmann-Voss 1987; Piraino <i>et al</i>. 1994).</p> <p> <b>Seasonality.</b> From April to November (Palombi 1935; Piraino <i>et al</i>. 1994) in theTyrrhenian and Ionian Seas.</p> <p> <b>Reproductive period.</b> April–November (Palombi 1935; Piraino <i>et al</i>. 1994).</p> <p> <b>Medusa.</b> Umbrella sphero-conical up to 0.55 mm high and wide, without manubrium and tentacles; 4 simple radial canals; 4 large, sac-like gonads on radial canals, not lobular, 8 adradial statocysts with 3 or 4 statoliths.</p> <p> <b>Cnidome.</b> Basitrichous isorhizas.</p> <p> <b>Distribution.</b> Endemic to Mediterranean Sea (Medel & López-González 1996; Bouillon <i>et al.</i> 2004; Gravili <i>et al</i>. 2008a).</p> <p> <b>Records in Salento.</b> Common in the Ionian Sea (Piraino <i>et al</i>. 1994; Kubota 2000) and Adriatic Sea, Apulian coasts (Kubota 2000).</p> <p> <b>Remarks.</b> The whole life cycle was examined in the present study. For more details about the systematics and ecology of this species see Kubota (1983, 1989, 2000), Piraino <i>et al.</i> (1994), Govindarajan <i>et al.</i> (2005).</p> <p> <b>References.</b> Kramp (1961), Kubota (1979, 1983, 1985, 1987, 2000), Gili (1986), Gili <i>et al.</i> (1988), Piraino <i>et al.</i> (1994), Bouillon <i>et al.</i> (2004), Gravili <i>et al</i>. (2008a).</p>Published as part of <i>Gravili, Cinzia, Vito, Doris De, Camillo, Cristina Gioia Di, Martell, Luis, Piraino, Stefano & Boero, Ferdinando, 2015, The non-Siphonophoran Hydrozoa (Cnidaria) of Salento, Italy with notes on their life-cycles: an illustrated guide, pp. 1-187 in Zootaxa 3908 (1)</i> on pages 86-87, DOI: 10.11646/zootaxa.3908.1.1, <a href="http://zenodo.org/record/242729">http://zenodo.org/record/242729</a>
Riflessioni su dogmatica e autonomia privata: il concetto di causa del contratto
No full textSempre più spesso si discute dell'attualità del metodo dogmatico e della sua stessa praticabilità in un quadro ordinamentale così frammentato tra fonti di natura e origine diverse. Il saggio evidenzia l'assoluta necessità di continuare a maneggiare il materiale normativo mediante gli strumenti dell'analisi concettuale e mette alla prova il ruolo indispensabile della dogmatica su uno dei terreni più tormentati della materia del contratto: la causa. Il capitolo ripercorre l'evoluzione del concetto di causa, le ragioni ideologiche e pratiche sottese alle principali elaborazioni e formula un'ipotesi di nozione di causa che consente di coniugare autonomia ed eteronomia
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