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

Preface

International audienc

L\u27exopinacoderme des Spongiaires

Volume: 178Start Page: 1193End Page: 120

Redescription de l'espèce-type du genre <i>Polymastia</i> Bowerbank, 1864 (Porifera, Demospongiae, Hadromerida)

L’espèce-type du genre Polymastia Bowerbank, 1864 est Spongia mamillaris Müller, 1806. Depuis pratiquement deux siècles le spécimen-type a été ignoré et vient d’être seulement récemment redécouvert au Zoological Museum à Copenhague (Danemark). Nous redécrivons ici ce spécimen-type. Il correspond aux spécimens récoltés dans les années récentes sur la côte ouest de la Suède et ne correspond absolument pas à l’espèce de Polymastia commune en Atlantique N-E (particulièrement sur les côtes de la mer du Nord, de la Manche et de la mer d’Irlande) appelée à tort «mamillaris» depuis Johnston (1842) et Bowerbank (1864). Cette Polymastia commune correspond à Polymastia (Spongia) penicillus (Montagu, 1818) d’après le réexamen d’un spécimen de Montagu (déposé au BMNH 30.7.3.26 dans le Cabinet du Dr Grant). Les différences principales entre P. mamillaris et P. penicillus sont le nombre de couches qui constituent le cortex, le type de spicules libres présent dans le choanosome qui sont des tylostyles intermédiaires chez P. penicillus et des tylostyles ectosomiques chez P. mamillaris, la forme des spicules cylindriques chez P. penicillus et fusiformes chez P. mamillaris et l’épaisseur des spicules qui varient entre 4 à 12 µm chez P. penicillus contre 8 à 24 µm chez P. mamillaris.The type species of the genus Polymastia Bowerbank, 1864 is Spongia mamillaris Müller, 1806. For almost two centuries the type specimen was ignored, but it was recently rediscovered in the Zoological Museum in Copenhagen (Denmark). This type specimen is here redescribed. It corresponds to specimens from the Swedish west coast collected recently close to the type locality and it does not correspond to the common Polymastia species from the NE Atlantic coast (North Sea, Channel Sea, British coasts) erroneously called "mamillaris" since Johnston (1842) and Bowerbank (1864). This common Polymastia corresponds to Polymastia (Spongia) penicillus (Montagu, 1818), according to a reexamination of a specimen from Montagu (BMNH 30.7.3.26 deposited in BMNH in the Dr Grant Cabinet). The main differences between P. mamillaris and P. penicillus are the number of layers of the cortex, the type of free spicules present in the choanosome which are intermediary tylostyles in P. penicillus versus ectosomal tylostyles in P. mamillaris, the shape of the spicules cylindrical in P. penicillus versus fusiform in P. mamillaris and the thickness of the spicules which vary from 4 to 12 µm in P. penicillus versus 8 to 24 µm in P. mamillaris.</p

Le prétendu cosmopolitisme chez les éponges : l&#039;exemple d’une &lt;i&gt;Polymastia&lt;/i&gt; (Porifera, Demospongiae, Hadromerida) commune de l&#039;Arctique

Depuis plusieurs années le cosmopolitisme chez les espèces d’éponges a été remis en question. Nous avons étudié des populations d’une Polymastia arctique très abondante communément identifiée à P. mamillaris (Müller, 1806). La redescription du matériel type de P. arctica (Merejkowsky, 1878) mis en synonymie avec P. mamillaris et sa comparaison avec les types de P. mamillaris et d’autres espèces communes de l’Arctique et de l’Atlantique du nord-est a montré que P. arctica est une espèce valide. Elle diffère de P. mamillaris et P. penicillus (Montagu, 1818) par la présence d’une couche épaisse de collagène (90-180 µm) dans l’ectosome et de spicules dans les lames cellulaires des papilles, et par la formation de bourgeon au sommet des papilles. Ce résultat montre une fois de plus que le prétendu cosmopolitisme chez les éponges est du à une systématique trop conservatoire plutôt qu’à une véritable homogénéité génétique.For several years the cosmopolitanism in sponges has been questioned. We studied populations of a very abundant Polymastia from the Arctic (White Sea and Barents Sea) commonly referred to P. mamillaris (Müller, 1806). The redescription of the type material of P. arctica (Merejkowsky, 1878) which was synonymized with P. mamillaris and its comparison with types of P. mamillaris and other common Arctic and NE Atlantic species shows that P. arctica is a valid species. It differs from P. mamillaris and P. penicillus by the presence of a thick (90-180 µm) collagenous layer in the cortex, the presence of spicules in the papilla internal laminae and the formation of buds at the top of the papillae. This result demonstrates that the often-cited “cosmopolitanism” in sponges is the result of over-conservative systematics rather than true genetic homogeneity.</p

ORIGINE ET EVOLUTION DES MECANISMES MOLECULAIRES CONTROLANT LA MORPHOGENESE CHEZ LES METAZOAIRES (UN NOUVEAU MODELE SPONGIAIRE, SYCON RAPHANUS (CALCISPONGIA, CALCARONEA))

ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF