148 research outputs found
Reconstruction of Family-Level Phylogenetic Relationships within Demospongiae (Porifera) Using Nuclear Encoded Housekeeping Genes
Background: Demosponges are challenging for phylogenetic systematics because of their plastic and relatively simple morphologies and many deep divergences between major clades. To improve understanding of the phylogenetic relationships within Demospongiae, we sequenced and analyzed seven nuclear housekeeping genes involved in a variety of cellular functions from a diverse group of sponges.
Methodology/Principal Findings: We generated data from each of the four sponge classes (i.e., Calcarea, Demospongiae, Hexactinellida, and Homoscleromorpha), but focused on family-level relationships within demosponges. With data for 21 newly sampled families, our Maximum Likelihood and Bayesian-based approaches recovered previously phylogenetically defined taxa: Keratosap, Myxospongiaep, Spongillidap, Haploscleromorphap (the marine haplosclerids) and Democlaviap. We found conflicting results concerning the relationships of Keratosap and Myxospongiaep to the remaining demosponges, but our results strongly supported a clade of Haploscleromorphap+Spongillidap+Democlaviap. In contrast to hypotheses based on mitochondrial genome and ribosomal data, nuclear housekeeping gene data suggested that freshwater sponges (Spongillidap) are sister to Haploscleromorphap rather than part of Democlaviap. Within Keratosap, we found equivocal results as to the monophyly of Dictyoceratida. Within Myxospongiaep, Chondrosida and Verongida were monophyletic. A well supported clade within Democlaviap, Tetractinellidap, composed of all sampled members of Astrophorina and Spirophorina (including the only lithistid in our analysis), was consistently revealed as the sister group to all other members of Democlaviap. Within Tetractinellidap, we did not recover monophyletic Astrophorina or Spirophorina. Our results also reaffirmed the monophyly of order Poecilosclerida (excluding Desmacellidae and Raspailiidae), and polyphyly of Hadromerida and Halichondrida.
Conclusions/Significance: These results, using an independent nuclear gene set, confirmed many hypotheses based on ribosomal and/or mitochondrial genes, and they also identified clades with low statistical support or clades that conflicted with traditional morphological classification. Our results will serve as a basis for future exploration of these outstanding questions using more taxon- and gene-rich datasets
Global Diversity of Sponges (Porifera)
With the completion of a single unified classification, the Systema Porifera (SP) and subsequent development of an online species database, the World Porifera Database (WPD), we are now equipped to provide a first comprehensive picture of the global biodiversity of the Porifera. An introductory overview of the four classes of the Porifera is followed by a description of the structure of our main source of data for this paper, the WPD. From this we extracted numbers of all ‘known’ sponges to date: the number of valid Recent sponges is established at 8,553, with the vast majority, 83%, belonging to the class Demospongiae. We also mapped for the first time the species richness of a comprehensive set of marine ecoregions of the world, data also extracted from the WPD. Perhaps not surprisingly, these distributions appear to show a strong bias towards collection and taxonomy efforts. Only when species richness is accumulated into large marine realms does a pattern emerge that is also recognized in many other marine animal groups: high numbers in tropical regions, lesser numbers in the colder parts of the world oceans. Preliminary similarity analysis of a matrix of species and marine ecoregions extracted from the WPD failed to yield a consistent hierarchical pattern of ecoregions into marine provinces. Global sponge diversity information is mostly generated in regional projects and resources: results obtained demonstrate that regional approaches to analytical biogeography are at present more likely to achieve insights into the biogeographic history of sponges than a global perspective, which appears currently too ambitious. We also review information on invasive sponges that might well have some influence on distribution patterns of the future
SPONGIAIRESDE LA ZONE ROCHEUSE LITTORALEDE BANYULS-SUR-MERI. ■ÉCOLOGIE ET RÉPARTITION
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Morphogenèse expérimentale des papilles inhalantes de l'éponge <i>Polymastia mamillaris</i> (Müller)
International audienceExperimental morphogenesis of inhalant papillae of the sponge Polymastia mamillaris is studied after basal cutting. There are three successive phases: cicatrization, formation of a blastema, differentiation and period of growth of the papilla. Cicatrization is showed by the formation of a transitory exopinacoderm. The regenerative blastema is formed by the migration of cells along the main spicular axis, principally archaeocytes and gray cells. In the immediale hours following the traumatism, gray celIs show a spectacular increase of glycogen;during the growth period gray cells become the preferential trophic source of the archaeocyles; this shows the role of the gray cells in energetic transfersLa morphogenèse expérimentale des papilles de l'éponge Polymastia mamillaris est étudiée après section basale. On observe trois phases successives: cicatrisation, formation d'un blastème, différenciation et croissance de la nouvelle papiJJe. La cicatrisation se manifeste par la mise en place d'un exopinacoderme transitoire. Le blastème de régénération se constitue par migration, le long des faisceaux de spicules, de cellules qui sont essentiellement des archaeocytes et des cellules grises. Dès les premières heures qui suivent le traumatisme, on observe dans les cellules grises un accroissement spectaculaire de la quantité du glycogène; au cours de la phase de croissance, les cellules grises deviennent la source trophique privilégiée des archaeocytes cn différenciation; ceci montre leur rôle dans les transferts énergétiques
SPONGIAIRESDE LA ZONE ROCHEUSE DE BANYULS-SUR-MERIL — SYSTÉMATIQUE
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UN PHÉNOMÈNE DE BOURGEONNEMENT EXTERNE CHEZ L'ÉPONGE AXINELLA DAMICORNIS (ESPER)
International audienceL'Eponge Axinella damicornis (Esper) émet des bourgeons externes. Ces bourgeons sont des expansions de la paroi externe des canaux exhalants; ils ont une composition cellulaire semblable à celle de l'ectosome, mais s'en distinguent par une densité en archaeocytes plus grande
SPONGIAIRESDE LA ZONE ROCHEUSE DE BANYULS-SUR-MERIL — SYSTÉMATIQUE
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Résultats Scientifiques des Campagnes de la ‘Calypso'. Campagne de la ‘Calypso' au large des côtes atlantiques de l'Amérique du Sud (1961-1962). I. 29. Spongiaires.
International audienceThe Sponges of the Atlantic Coast of South-America are as yet little known. The material brought back bythe « Calypso » therefore adds mush to our knowledge. 61 species have been identified, of which 31 are new to science. These species can be classified into two populations : one tropical, extending to 23° S, the other with antarctic affinity.Les Spongiaires de la côte atlantique d'Amérique du Sud sont encore mal connus. Le matériel rapporté par la« Calypso » permet en partie de combler cette lacune.61 espèces ont éte identifiées doni 31 sont nouvelles pour la science. Ces espèces se répartissent en deux contingents: un contingent tropical jusqu'à 23° S, puis un contingent à affinité antarctique
Structure et ultrastructure des papilles d'Eponges du genre Polymastia Bowerbank
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