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Franz B. Lang - One of the best experts on this subject based on the ideXlab platform.
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DOI: 10.1080/10635150500221044 Poriferan mtDNA and Animal Phylogeny Based on Mitochondrial Gene Arrangements
2008Co-Authors: Dennis V. Lavrov, Franz B. LangAbstract:Abstract.—Phylogenetic relationships among the metazoan phyla are the subject of an ongoing controversy. Analysis of mitochondrial gene arrangements is a powerful tool to investigate these relationships; however, its previous application outside of individual animal phyla has been hampered by the lack of informative out-group data. To address this shortcoming, we determined complete mitochondrial DNA sequences for the demosponges Geodia neptuni and Tethya actinia, two representatives of the most basal animal phylum, the Porifera. With sponges as an outgroup, we investigated phylogenetic relationships of nine bilaterian phyla using both breakpoint analysis of global mitochondrial gene arrangements and maximum parsimony analysis of mitochondrial gene adjacencies. Our results provide strong support for a group that includes protostome (but not deuterostome) coelomate, pseudocoelomate, and acoelomate animals, thus clearly rejecting the Coelomata hypothesis. Two other groups of bilaterian animals, Lophotrochozoa and Ambulacraria, are also supported by our analyses. However, due to the remarkable stability of mitochondrial gene arrangements in Deuterostomia and the Ecdysozoa, conclusions on their evolutionary history cannot be drawn. [Coelomata hypothesis; metazoan phylogeny; mitochondrial DNA; phylogenetic inference; Porifera.] Metazoan phyla can be defined as “the largest groupings of taxa that can readily be seen to be more closely related to each other than to any other groups ” (Budd an
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Poriferan mtDNA and animal phylogeny based on mitochondrial gene arrangements
2003Co-Authors: Dennis V. Lavrov, Franz B. LangAbstract:Abstract.—Phylogenetic relationships among the metazoan phyla are the subject of an ongoing controversy. Analysis of mito-chondrial gene arrangements is a powerful tool to investigate these relationships; however, its previous application outside of individual animal phyla has been hampered by the lack of informative out-group data. To address this shortcoming, we determined complete mitochondrial DNA sequences for the demosponges Geodia neptuni and Tethya actinia, two representa-tives of the most basal animal phylum, the Porifera. With sponges as an outgroup, we investigated phylogenetic relationships of nine bilaterian phyla using both breakpoint analysis of global mitochondrial gene arrangements and maximum parsimony analysis of mitochondrial gene adjacencies. Our results provide strong support for a group that includes protostome (but not deuterostome) coelomate, pseudocoelomate, and acoelomate animals, thus clearly rejecting the Coelomata hypothesis. Two other groups of bilaterian animals, Lophotrochozoa and Ambulacraria, are also supported by our analyses. However, due to the remarkable stability of mitochondrial gene arrangements in Deuterostomia and the Ecdysozoa, conclusions on their evolutionary history cannot be drawn. [Coelomata hypothesis; metazoan phylogeny; mitochondrial DNA; phylogenetic inference; Porifera.] Metazoan phyla can be defined as “the largest group-ings of taxa that can readily be seen to be more closely related to each other than to any other groups ” (Budd an
Dennis V. Lavrov - One of the best experts on this subject based on the ideXlab platform.
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DOI: 10.1080/10635150500221044 Poriferan mtDNA and Animal Phylogeny Based on Mitochondrial Gene Arrangements
2008Co-Authors: Dennis V. Lavrov, Franz B. LangAbstract:Abstract.—Phylogenetic relationships among the metazoan phyla are the subject of an ongoing controversy. Analysis of mitochondrial gene arrangements is a powerful tool to investigate these relationships; however, its previous application outside of individual animal phyla has been hampered by the lack of informative out-group data. To address this shortcoming, we determined complete mitochondrial DNA sequences for the demosponges Geodia neptuni and Tethya actinia, two representatives of the most basal animal phylum, the Porifera. With sponges as an outgroup, we investigated phylogenetic relationships of nine bilaterian phyla using both breakpoint analysis of global mitochondrial gene arrangements and maximum parsimony analysis of mitochondrial gene adjacencies. Our results provide strong support for a group that includes protostome (but not deuterostome) coelomate, pseudocoelomate, and acoelomate animals, thus clearly rejecting the Coelomata hypothesis. Two other groups of bilaterian animals, Lophotrochozoa and Ambulacraria, are also supported by our analyses. However, due to the remarkable stability of mitochondrial gene arrangements in Deuterostomia and the Ecdysozoa, conclusions on their evolutionary history cannot be drawn. [Coelomata hypothesis; metazoan phylogeny; mitochondrial DNA; phylogenetic inference; Porifera.] Metazoan phyla can be defined as “the largest groupings of taxa that can readily be seen to be more closely related to each other than to any other groups ” (Budd an
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Poriferan mtDNA and animal phylogeny based on mitochondrial gene arrangements
2003Co-Authors: Dennis V. Lavrov, Franz B. LangAbstract:Abstract.—Phylogenetic relationships among the metazoan phyla are the subject of an ongoing controversy. Analysis of mito-chondrial gene arrangements is a powerful tool to investigate these relationships; however, its previous application outside of individual animal phyla has been hampered by the lack of informative out-group data. To address this shortcoming, we determined complete mitochondrial DNA sequences for the demosponges Geodia neptuni and Tethya actinia, two representa-tives of the most basal animal phylum, the Porifera. With sponges as an outgroup, we investigated phylogenetic relationships of nine bilaterian phyla using both breakpoint analysis of global mitochondrial gene arrangements and maximum parsimony analysis of mitochondrial gene adjacencies. Our results provide strong support for a group that includes protostome (but not deuterostome) coelomate, pseudocoelomate, and acoelomate animals, thus clearly rejecting the Coelomata hypothesis. Two other groups of bilaterian animals, Lophotrochozoa and Ambulacraria, are also supported by our analyses. However, due to the remarkable stability of mitochondrial gene arrangements in Deuterostomia and the Ecdysozoa, conclusions on their evolutionary history cannot be drawn. [Coelomata hypothesis; metazoan phylogeny; mitochondrial DNA; phylogenetic inference; Porifera.] Metazoan phyla can be defined as “the largest group-ings of taxa that can readily be seen to be more closely related to each other than to any other groups ” (Budd an
Reinhard M. Rieger - One of the best experts on this subject based on the ideXlab platform.
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The coelom and the origin of the annelid body plan
Hydrobiologia, 2005Co-Authors: Reinhard M. RiegerAbstract:The biphasic life cycle in annelids is characterized by two completely different types of organisation, i.e. the acoelomate/pseudocoelomate larva and the coelomate adult. Based on this observation the recent literature on the different assumptions on the organisation of the bilaterian stem species with special emphasis on the evolution of the annelid body plan is reviewed. The structure of the coelomic lining ranges between a simple myoepithelium composed of epithelio-muscle cells and a non-muscular peritoneum that covers the body wall muscles. The direction of the evolution of these linings is discussed with respect to coelomogenesis. As the coelom originates from mesodermal cell bands, different assumption on the acoelomate condition in Bilateria can be substantiated. The origin of segmentation in annelids is explained by current hypothesis. Although no final decision can be made concerning the origin of the annelid body plan and the organisation of the bilaterian stem species, this paper elaborates those questions that need to be resolved to unravel the relation between the different body plans.
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larval planktotrophy a primitive trait in the bilateria
Acta Zoologica, 1995Co-Authors: Gerhard Haszprunar, Luitfried V Salviniplawen, Reinhard M. RiegerAbstract:The concept of Gosta Jagersten of a primary biphasic metazoan life-cycle, consisting of a planktotrophic larva and a benthic adult, forms the basis for several theories on metazoan phylogeny. In this paper the assumed planktotrophic life-style of the larva is critically analyzed and reconsidered. It is shown, in particular for the Mollusca, that a biphasic life-cycle with a lecithotrophic larva is probably the plesiomorphic condition. Character distribution and structural data suggest a parallel evolution of the downstream collecting system used in planktotrophic larvae or filter-feeding adults of gastropods, bivalves and other spiralian or aschelminth taxa. In the basic metazoans (Parazoa, Placozoa, coelenterates) direct or lecithotrophic development dominates by far. For the acoelomate (Platyhelminthes, Gnathostomulida) and pseudocoelomate taxa direct development is probably the plesiomorphic condition. The structural similarities of the upstream collecting system in tentaculate and deuterostome phyla may also be explained by parallel events of heterochrony out of an ancestor with adult filter-feeding. The main conclusion of this survey is that larval planktotrophy is likely to be secondary and not a plesiomorphic condition among the Bilateria. Accordingly, theories which are based on the assumed plesiomorphy of larval planktotrophy of the Bilateria, need careful reevaluation.
James R. Garey - One of the best experts on this subject based on the ideXlab platform.
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18S rRNA suggests that Entoprocta are protostomes, unrelated to Ectoprocta.
Journal of Molecular Evolution, 1996Co-Authors: L. Y. Mackey, Birgitta Winnepenninckx, R. De Wachter, P. Emschermann, Thierry Backeljau, James R. GareyAbstract:The Ento- and Ectoprocta are sometimes placed together in the Bryozoa, which have variously been regarded as proto- or deuterostomes. However, Entoprocta have also been allied to the pseudocoelomates, while Ectoprocta are often united with the Brachiopoda and Phoronida in the (super)phylum Lophophorata. Hence, the phylogenetic relationships of these taxa are still much debated. We determined complete 18S rRNA sequences of two entoprocts, an ectoproct, an inarticulate brachiopod, a phoronid, two annelids, and a platyhelminth. Phylogenetic analyses of these data show that (1) entoprocts and lophophorates have spiralian, protostomous affinities, (2) Ento- and Ectoprocta are not sister taxa, (3) phoronids and brachiopods form a monophyletic clade, and (4) neither Ectoprocta or Annelida appear to be monophyletic. Both deuterostomous and pseudocoelomate features may have arisen at least two times in evolutionary history. These results advocate a Spiralia-Radialia-based classification rather than one based on the Protostomia-Deuterostomia concept.
L. Y. Mackey - One of the best experts on this subject based on the ideXlab platform.
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18S rRNA suggests that Entoprocta are protostomes, unrelated to Ectoprocta.
Journal of Molecular Evolution, 1996Co-Authors: L. Y. Mackey, Birgitta Winnepenninckx, R. De Wachter, P. Emschermann, Thierry Backeljau, James R. GareyAbstract:The Ento- and Ectoprocta are sometimes placed together in the Bryozoa, which have variously been regarded as proto- or deuterostomes. However, Entoprocta have also been allied to the pseudocoelomates, while Ectoprocta are often united with the Brachiopoda and Phoronida in the (super)phylum Lophophorata. Hence, the phylogenetic relationships of these taxa are still much debated. We determined complete 18S rRNA sequences of two entoprocts, an ectoproct, an inarticulate brachiopod, a phoronid, two annelids, and a platyhelminth. Phylogenetic analyses of these data show that (1) entoprocts and lophophorates have spiralian, protostomous affinities, (2) Ento- and Ectoprocta are not sister taxa, (3) phoronids and brachiopods form a monophyletic clade, and (4) neither Ectoprocta or Annelida appear to be monophyletic. Both deuterostomous and pseudocoelomate features may have arisen at least two times in evolutionary history. These results advocate a Spiralia-Radialia-based classification rather than one based on the Protostomia-Deuterostomia concept.
