Untersuchungen uber die Entwickelungs-Gesetze der organischen Welt wahrend der Bildungs-Zeit unserer Erd-Oberflache : eine von der Franzosischen Akademie im Jahre 1857 gekronte Preisschrift, mit ihrer Erlaubniss Deutsch herausgegeben /

Bronn, H. G.

doi:10.5962/bhl.title.50675

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“…Three major fundamental types of symmetry are classically recognised among adult metazoans (asymmetrical, radial, bilateral), to which adds the more anecdotical spherical symmetry [23,27,37,61,87,98,169]. I propose hereafter a revised classification of the types of symmetry for multicellular animals (Fig.…”

Section: Types Of Symmetry and Body Polarity Axes: The Promorphology ...mentioning

confidence: 99%

Early evolution of symmetry and polarity in metazoan body plans

Manuel

2008

Comptes Rendus. Biologies

111

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The early diverging metazoan lineages have highly disparate adult body plan geometries, which can be characterised in terms of five major types of symmetry (asymmetrical, spherical, cylindrical, n-radial, bilateral). Patterns of evolutionary changes in symmetry types and the homology of body axes across lineages are discussed here by confronting evidence from comparative anatomy, phylogeny, genomics and evo-devo. The conventional scenario, postulating a graded complexification from asymmetry to radial and finally bilateral symmetry, is considered untenable. Cylindrical symmetry is likely to be the ancestral type from which derived all remaining types through multiple convergences. Recent proposals prompted by molecular data that the bilateral anatomies of many cnidarians and of the Bilateria are homologous are clearly not supported. The Hox-based patterning system operating along the antero-posterior axis of the Bilateria does not seem to predate their divergence with the Cnidaria, but intercellular signalling systems, notably the Wnt pathway, could have been involved in generating the main body axis in the last common ancestor of the Metazoa.

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Section: Types Of Symmetry and Body Polarity Axes: The Promorphology ...mentioning

confidence: 99%

Early evolution of symmetry and polarity in metazoan body plans

Manuel

2008

Comptes Rendus. Biologies

111

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“…In 1858 Heinrich Georg Bronn [ 95 ] depicted a system of animals, as evidenced by the fossil record, in the form of a branching diagram drawn to resemble an actual tree (Figure 20 ) and described as a Baum-förmige Bilde des Systems with Äste (branches). His tree depicted a series of species, of increasing organisational perfection, succeeding each other as time progresses; this succession continues on all branches, although at any point in time some new species are necessarily more-perfect than others on lower branches [[ 96 ], pp.110-116].…”

Section: Trees 1837-1859mentioning

confidence: 99%

Trees and networks before and after Darwin

Ragan

2009

Biol Direct

128

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It is well-known that Charles Darwin sketched abstract trees of relationship in his 1837 notebook, and depicted a tree in the Origin of Species (1859). Here I attempt to place Darwin's trees in historical context. By the mid-Eighteenth century the Great Chain of Being was increasingly seen to be an inadequate description of order in nature, and by about 1780 it had been largely abandoned without a satisfactory alternative having been agreed upon. In 1750 Donati described aquatic and terrestrial organisms as forming a network, and a few years later Buffon depicted a network of genealogical relationships among breeds of dogs. In 1764 Bonnet asked whether the Chain might actually branch at certain points, and in 1766 Pallas proposed that the gradations among organisms resemble a tree with a compound trunk, perhaps not unlike the tree of animal life later depicted by Eichwald. Other trees were presented by Augier in 1801 and by Lamarck in 1809 and 1815, the latter two assuming a transmutation of species over time. Elaborate networks of affinities among plants and among animals were depicted in the late Eighteenth and very early Nineteenth centuries. In the two decades immediately prior to 1837, so-called affinities and/or analogies among organisms were represented by diverse geometric figures. Series of plant and animal fossils in successive geological strata were represented as trees in a popular textbook from 1840, while in 1858 Bronn presented a system of animals, as evidenced by the fossil record, in a form of a tree. Darwin's 1859 tree and its subsequent elaborations by Haeckel came to be accepted in many but not all areas of biological sciences, while network diagrams were used in others. Beginning in the early 1960s trees were inferred from protein and nucleic acid sequences, but networks were re-introduced in the mid-1990s to represent lateral genetic transfer, increasingly regarded as a fundamental mode of evolution at least for bacteria and archaea. In historical context, then, the Network of Life preceded the Tree of Life and might again supersede it.ReviewersThis article was reviewed by Eric Bapteste, Patrick Forterre and Dan Graur.

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“…La Naturphilosophie, courant intellectuel qui s'est épanoui en Allemagne à partir de l'extrême fin du xviii e siècle, a largement contribué à diffuser cette conception [12]. Or c'est ce fonds culturel qui forme l'héritage de Bronn, lequel a été formé par des Naturphilosophen ou des sympathisants, et il est connu parmi les naturalistes de son temps pour ses théories générales sur l'histoire de la Terre ou la morphologie des êtres vivants [13,14]. Il a proposé des « lois de développement » (Entwickelungsgesetze) qui rendent comptent aussi bien de l'embryogenèse des organisme que de la succession des espèces à la surface de la Terre, une succession qu'il n'explique pas par une évolution mais par des apparitions multiples, chacune plus élaborée que la précédente.…”

Section: Le Contexte Allemand Et Les Premiers Travaux De Haeckelunclassified

Haeckel, un darwinien allemand ?

Schmitt

2008

Comptes Rendus. Biologies

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Accepté après révision le12 juillet 2008 Disponible sur Internet le 28 novembre 2008 Présenté par Claude Combes RésuméLe biologiste allemand Ernst Haeckel (1834Haeckel ( -1919 est souvent considéré comme le plus éminent des darwiniens de son pays, dans la mesure où, dès 1862, il déclarait accepter les conclusions auxquelles Darwin était parvenu trois ans plus tôt dans l'Origine des espèces et où, par la suite, il n'eut de cesse de se proclamer partisan du naturaliste anglais et de défendre la théorie de l'évolution. Néanmoins, l'examen détaillé de ses ouvrages, en particulier de la Morphologie générale (1866), révèle qu'il s'inscrit dans une tradition fort éloignée de la pensée de Darwin. Malgré son acceptation de l'idée de sélection naturelle, qu'il érige en argument en faveur du matérialisme, il adopte en réalité une vision de l'évolution assez proche à certains égards de celle de Lamarck. Il témoigne ainsi des ambiguïtés de la réception du darwinisme en Allemagne dans la seconde moitié du xix e siècle.

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Untersuchungen uber die Entwickelungs-Gesetze der organischen Welt wahrend der Bildungs-Zeit unserer Erd-Oberflache : eine von der Franzosischen Akademie im Jahre 1857 gekronte Preisschrift, mit ihrer Erlaubniss Deutsch herausgegeben /

Cited by 4 publications

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Early evolution of symmetry and polarity in metazoan body plans

Early evolution of symmetry and polarity in metazoan body plans

Trees and networks before and after Darwin

Haeckel, un darwinien allemand ?

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