The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Michelle Klautau - One of the best experts on this subject based on the ideXlab platform.
-
microbiota of the alien species paraleucilla magna porifera calcarea from the southwestern atlantic and a comparison with that of other Calcareous Sponges
bioRxiv, 2019Co-Authors: Maira Ferreira Lopes, Michelle Klautau, Beatriz Magna, Eduardo L Esteves, Rodolpho M AlbanoAbstract:Sponges (Porifera) co-evolved with microorganisms in a well-established symbiotic relationship. Based on this characteristic, Sponges can be separated into high microbial abundance (HMA) and low microbial abundance (LMA) species. Paraleucilla magna (Calcarea, Porifera) is an alien species of ecological importance in the Brazilian coastline. Little is known about the composition of its microbiota and that of other Calcareous species, especially those inhabiting the Southwest Atlantic. Here, we describe the microbiota of P. magna and compare it to that of other Calcareous Sponge species for which such data exist. P. magna’s microbiota shows a lower diversity than that of Clathrina clathrus, C. coriacea, Leucosolenia sp., Leuconia sp. and Leucetta antarctica. P. magna microbiota is dominated by two bacterial OTUs of the Alphaproteobacteria class, that could not be classified beyond class (OTU001) and family levels (OTU002; Rhodospirillaceae). The Thaumarcheota was the predominant archaeal phylum in P. magna, with OTUs mainly affiliated to the genus candidatus Nitrosopumilus. The comparison with other Calcareous species showed that microbiota composition correlated well with Sponge phylogenetic affiliation. Metabolic prediction with PICRUSt software of P. magna bacterial microbiota indicated that membrane transport and carbohydrate, amino acid and energy metabolisms were most abundant while, for the archaeal domain, pathways related to translation, and energy metabolisms were predominant. Predicted metabolic features were compared between the different Sponge species and seawater samples, showing that pathways related to cell motility, membrane transport, genetic information processing, xenobiotics metabolism and signal transduction are higher in the former while amino acid and nucleotide metabolism, translation, replication and repair, folding, sorting and degradation and glycan biosynthesis and metabolism are abundant in the latter. This study shows that P. magna’s microbiota is typical of an LMA Sponge and that it differs from the microbiota of other Calcareous Sponges both in its composition and in predicted metabolic pathways.
-
gene flow and differentiation in a native Calcareous Sponge porifera with unknown dispersal phase
Marine Biodiversity, 2018Co-Authors: Andre Padua, Haydée A. Cunha, Michelle KlautauAbstract:Clathrina aurea is a Calcareous Sponge with a wide distribution along the Eastern South American coast. Despite this wide distribution, larvae have never been observed in this species. In the present work, we investigated the population differentiation and dispersal capacity of this native species along the Southwestern Atlantic (South-Southeastern Brazil) using genetic data (microsatellites) and morphological comparison. Clathrina aurea presented high genetic diversity with a high number of alleles and high heterozygosity compared to other Sponge species. On the other hand, our results showed inbreeding and significant population structure, although with some evidence of long-distance dispersal. The structuring pattern observed could be a result of the influence of the local marine landscape/environment and ocean currents in a stepping-stone model. The external morphology was conservative; however, spicule measurements were significantly different within and among localities, evidencing its high variability in the class Calcarea. This is the first population genetics study of a native Calcareous Sponge using microsatellites.
-
a new genus of Calcareous Sponge discovered in the caribbean sea bidderia gen nov porifera calcarea calcinea
Zootaxa, 2018Co-Authors: Matheus V Lopes, Thierry Perez, Baslavi Condorlujan, Fernanda Azevedo, Michelle KlautauAbstract:Calcareous Sponges from the Lesser Antilles were recently inventoried and several specimens morphologically resembling species of the genus Ascoleucetta were collected. Morphological and molecular (C-LSU and ITS) analyses indicated that these specimens from the Lesser Antilles constituted a new genus. They lack the conspicuous and very characteristic ornamentation of the inhalant apertures found in two out of three species of Ascoleucetta , including the type species A. compressa . In the molecular analyses, the specimens clustered as an independent lineage, distant from the clade of A. compressa . Based on these results, we decided to erect a new genus, Bidderia gen. nov., whose type species is Bidderia bicolora gen. nov. sp. nov. Considering this new discovery, we are proposing to transfer the species A. amitsba to the genus Bidderia gen. nov. and to rediagnose Ascoleucetta .
-
exploitation of micro refuges and epibiosis survival strategies of a Calcareous Sponge
Journal of the Marine Biological Association of the United Kingdom, 2016Co-Authors: Barbara Ribeiro, Andre Padua, Marcio R Custodio, Paulo Cesar Paiva, Michelle KlautauAbstract:Sponges interact in various ways with a wide variety of organisms in benthic communities and ecological interactions may influence the distribution, abundance and diversity of these organisms in different sites. Although several studies have already been developed for Demospongiae, knowledge of ecological interactions in the class Calcarea is lacking. Some Calcareous Sponges are considered weak competitors for space and to have developed strategies to survive in highly dynamic environments, such as exploitation of micro refuges and epibiosis. We aimed to investigate the influence of intra- and interspecific interactions in the abundance, growth and lifespan of the Calcareous Sponge Clathrina aurea in south-eastern Brazil. Two peaks of abundance and area coverage were observed during the studied year, probably associated with reproductive effort. We found no evidence of intra- or interspecific competition between the Sponge and the benthic community. Clathrina aurea was found using parts of other organisms as substrate (epibiosis), such as algae, demoSponges and corals. It was seen that the interaction of the Sponge with coral polyps positively affects the lifespan of Sponge individuals and the interstices of corals probably promote a micro refuge for C. aurea against competitors for space and predators.
-
life history and reproductive dynamics of the cryptogenic Calcareous Sponge sycettusa hastifera porifera calcarea living in tropical rocky shores
Journal of the Marine Biological Association of the United Kingdom, 2016Co-Authors: Emilio Lanna, Michelle KlautauAbstract:Life history accounts for the chance of survival and reproductive success of a species, considering, for example, when, how often and how much a species reproduces. Consequently, it is directly related to the success or failure of bioinvasions. Here, we investigated some aspects of the life history of the cryptogenic Calcareous Sponge Sycettusa hastifera . A population from Arraial do Cabo, Brazil (south-western Atlantic) was investigated from September 2008 to December 2009 by monthly collections and histological analyses. We observed that S. hastifera reproduced continuously throughout the year without seasonality and presented high fecundity. The fecundity was not different depending on the Sponge body part (top or base), but it was related to the wet weight of the Sponge (although a minimum size was not required for reproduction). Reproduction could not be predicted by the seawater temperature. The reproductive characteristics of S. hastifera were similar to those of other previously studied Calcareous Sponges. Sycettusa hastifera shows traits of an invasive species, such as high fecundity, short life cycle, early sexual maturity and the ability to use pioneer habitats. Consequently, it possesses several characteristics that would allow it to invade new areas.
Mahmoud Reza Majidifard - One of the best experts on this subject based on the ideXlab platform.
-
porosphaera globularis phillips 1829 porifera calcarea from the maastrichtian of the farokhi formation of central iran
Cretaceous Research, 2012Co-Authors: Markus Wilmsen, Franz T Fursich, Mahmoud Reza MajidifardAbstract:Abstract A small faunule of the Calcareous Sponge Porosphaera globularis ( Phillips, 1829 ) (Calcarea, Minchinellidae) is described and illustrated from the Maastrichtian Farokhi Formation of Central Iran. The shape of the Sponges varies from near-spherical to pyriform with diameters ranging between 5 and 13 mm. The surfaces show small, equidistant apertures corresponding to radiating oscular tubes within a choanosomal skeleton consisting of large tetractines fused to a rigid framework. Radially arranged superficial grooves may also be present in some specimens. External attachment scars have not been observed, but perforations in two specimens may represent sipunculan worm borings. A quiet and fairly deep-water environment can be inferred as the habitat of the Sponges, corresponding to data in the literature. So far, P. globularis was known only from the Upper Cretaceous (Cenomanian–Maastrichtian) of the Boreal Realm. The record from Central Iran is the southernmost occurrence of P. globularis (palaeo-latitude ca. 20°N) known to date and is the first description of the species from Iran and the Middle East.
Emilio Lanna - One of the best experts on this subject based on the ideXlab platform.
-
influence of endogenous and exogenous factors on the reproductive output of a cryptogenic Calcareous Sponge
Marine Biodiversity, 2019Co-Authors: Vanessa P S B Calazans, Emilio LannaAbstract:The propagule pressure exerts an important role during the bioinvasion process. However, this biological characteristic of invasive species is still poorly understood for marine invertebrates. Here, we investigated aspects of the propagule pressure of the cryptogenic Calcareous Sponge Heteropia cf. glomerosa in the northeastern coast of Brazil. The investigated population was continuously reproductively active. Oocytes were present mainly during the rainy season, while embryos and larvae only during the dry season. The reproductive effort of this species was among the highest observed for Sponges. The wet weight of the species did not influence on the reproductive output, but the number of tubes with apical osculum comprising the Sponge was related to the number of oocytes. The reproduction of H. cf. glomerosa seemed to be driven by temperature, tides, and photoperiod. Our findings indicate that this species presents an opportunistic life history strategy enabling it to reproduce early in its life cycle with abundant propagules. As photoperiod is one of the drivers of its reproduction, it is expected that in higher latitudes (where this species has been found), the reproductive effort may exert an even higher pressure for the establishment and dispersion of the species. If H. cf. glomerosa is confirmed as a non-native in the study area, our results indicate that the best time to apply field efforts to avoid the expansion and establishment of the species is during the rainy period, when fewer larvae are found.
-
life history and reproductive dynamics of the cryptogenic Calcareous Sponge sycettusa hastifera porifera calcarea living in tropical rocky shores
Journal of the Marine Biological Association of the United Kingdom, 2016Co-Authors: Emilio Lanna, Michelle KlautauAbstract:Life history accounts for the chance of survival and reproductive success of a species, considering, for example, when, how often and how much a species reproduces. Consequently, it is directly related to the success or failure of bioinvasions. Here, we investigated some aspects of the life history of the cryptogenic Calcareous Sponge Sycettusa hastifera . A population from Arraial do Cabo, Brazil (south-western Atlantic) was investigated from September 2008 to December 2009 by monthly collections and histological analyses. We observed that S. hastifera reproduced continuously throughout the year without seasonality and presented high fecundity. The fecundity was not different depending on the Sponge body part (top or base), but it was related to the wet weight of the Sponge (although a minimum size was not required for reproduction). Reproduction could not be predicted by the seawater temperature. The reproductive characteristics of S. hastifera were similar to those of other previously studied Calcareous Sponges. Sycettusa hastifera shows traits of an invasive species, such as high fecundity, short life cycle, early sexual maturity and the ability to use pioneer habitats. Consequently, it possesses several characteristics that would allow it to invade new areas.
-
environmental effects on the reproduction and fecundity of the introduced Calcareous Sponge paraleucilla magna in rio de janeiro brazil
Marine Ecology, 2015Co-Authors: Emilio Lanna, Paulo Cesar Paiva, Rodolfo Paranhos, Michelle KlautauAbstract:The Calcareous Sponge Paraleucilla magna (Porifera, Calcarea) has been the subject of several studies in the last decade. It was first described along the Brazilian coast, where it is considered cryptogenic, and was subsequently found in the Mediterranean, where it is considered invasive. The wide artificial distribution of this species allows us to compare different aspects of the biology of an introduced species in different locations. Here, we analysed the effects of selected environmental parameters on the reproductive dynamics of P. magna in Rio de Janeiro (Brazil) over 18 months and compared our results with those obtained for the same species in the Mediterranean Sea. Specimens were collected monthly and analysed through histological methods. The density of reproductive elements in each month was calculated, and the effects of environmental parameters (photoperiod, precipitation, temperature, phytoplankton and bacterioplankton) were analysed using a regression tree analysis. Paraleucilla magna was reproductive throughout the study period. The densities of the reproductive elements (oocytes, embryos and larvae) showed no seasonality, and this species presented one of the highest reproductive efforts documented to date in the phylum Porifera (99.0 oocytes · mm−3; 89.0 embryos · mm−3; 319.0 larvae · mm−3). The main environmental parameters related to the reproduction of P. magna were temperature, photoperiod and bacterioplankton. Temperature was the main driver associated with the densities of oocytes and embryos, while bacterioplankton was the main driver of larvae (positive relationships). In Rio de Janeiro, larvae were present and continuously released. This strategy is different from that observed in the Mediterranean, where a larger larval output was observed but only during the summer months. Our results show that P. magna is a species with a strong invasive potential, considering its high and continuous reproductive effort. This high fecundity stimulated by high temperatures may be a key factor contributing to the growth of P. magna populations and its invasion of new areas.
-
three new species of the genus paraleucilla dendy 1892 porifera calcarea from the coast of bahia state northeastern brazil
Zootaxa, 2014Co-Authors: Fernanda F Cavalcanti, Carla Menegola, Emilio LannaAbstract:Three new species of Calcareous Sponges from the coast of Bahia State, NE Brazil are described. All of them belong to the genus Paraleucilla (Calcaronea, Leucosolenida, Amphoriscidae): P. solangeae sp. nov., P. oca sp. nov., and P. incomposita sp. nov. The number of species recorded from the Bahia coast has thus increased from 10 to 13. Including these new species, there are now 50 Calcareous Sponge species known from the entire Brazilian coast. Paraleucilla is now composed of 11 species, six of them occurring along the southwestern Atlantic Ocean. The remaining species occur mainly in the Indian Ocean, and also in the Pacific Ocean, Red Sea and Mediterranean Sea. An identification key for all Paraleucilla species is provided. This paper is dedicated to the memory of Professor Solange Peixinho, to acknowledge her contribution to our understanding of the biodiversity of Calcarea from the Bahia coast in Brazil.
-
recruitment habitat selection and larval photoresponse of paraleucilla magna porifera calcarea in rio de janeiro brazil
Marine Ecology, 2013Co-Authors: Andre Padua, Paulo Cesar Paiva, Emilio Lanna, Carla Zilberberg, Michelle KlautauAbstract:Little is known about the recruitment and behaviour of Sponge larvae, especially of the class Calcarea. The Calcareous Sponge Paraleucilla magna is very common in Southeast Brazil, where it is considered a cryptogenic species. This study quantified recruitment rates in shaded and illuminated habitats for 2 years in Rio de Janeiro, Brazil, and analyzed larval photoresponses of this species. Four structures, each containing a shaded and an illuminated surface, were exchanged every 3 months for 2 years. The number of recruits was quantified on each plate. In the laboratory, larvae of P. magna were placed in halfshaded Petri dishes and the number of settlers in each side was counted after 24 h. Paraleucilla magna recruited continuously throughout the experiment. Recruits occurred in greater abundance on shaded surfaces than on illuminated surfaces, and the larvae were negatively phototactic in vitro. Despite the possible influence of other factors in the recruitment of Sponges (such as sedimentation, competition and predation), the prevalence of P. magna in shaded habitats may also be related to larval choice.
Maja Adamska - One of the best experts on this subject based on the ideXlab platform.
-
Calcareous Sponge genomes reveal complex evolution of α carbonic anhydrases and two key biomineralization enzymes
BMC Evolutionary Biology, 2014Co-Authors: Oliver Voigt, Marcin Adamski, Kasia Sluzek, Maja AdamskaAbstract:Calcium carbonate biominerals form often complex and beautiful skeletal elements, including coral exoskeletons and mollusc shells. Although the ability to generate these carbonate structures was apparently gained independently during animal evolution, it sometimes involves the same gene families. One of the best-studied of these gene families comprises the α- carbonic anhydrases (CAs), which catalyse the reversible transformation of CO2 to HCO3− and fulfill many physiological functions. Among Porifera –the oldest animal phylum with the ability to produce skeletal elements– only the class of Calcareous Sponges can build calcitic spicules, which are the extracellular products of specialized cells, the sclerocytes. Little is known about the molecular mechanisms of their synthesis, but inhibition studies suggest an essential role of CAs. In order to gain insight into the evolution and function of CAs in biomineralization of a basal metazoan species, we determined the diversity and expression of CAs in the Calcareous Sponges Sycon ciliatum and Leucosolenia complicata by means of genomic screening, RNA-Seq and RNA in situ hybridization expression analysis. Active biomineralization was located with calcein-staining. We found that the CA repertoires of two Calcareous Sponge species are strikingly more complex than those of other Sponges. By characterizing their expression patterns, we could link two CAs (one intracellular and one extracellular) to the process of calcite spicule formation in both studied species. The extracellular biomineralizing CAs seem to be of paralogous origin, a finding that advises caution against assuming functional conservation of biomineralizing genes based upon orthology assessment alone. Additionally, Calcareous Sponges possess acatalytic CAs related to human CAs X and XI, suggesting an ancient origin of these proteins. Phylogenetic analyses including CAs from genomes of all non-bilaterian phyla suggest multiple gene losses and duplications and presence of several CAs in the last common ancestor of metazoans. We identified two key biomineralization enzymes from the CA-family in Calcareous Sponges and propose their possible interaction in spicule formation. The complex evolutionary history of the CA family is driven by frequent gene diversification and losses. These evolutionary patterns likely facilitated the numerous events of independent recruitment of CAs into biomineralization within Metazoa.
-
genome wide analysis of the sox family in the Calcareous Sponge sycon ciliatum multiple genes with unique expression patterns
Evodevo, 2012Co-Authors: Sofia A V Fortunato, Hans Tore Rapp, Sven Leininger, Marcin Adamski, Brith Bergum, Corina Guder, Signe Jordal, Christin Zwafink, Maja AdamskaAbstract:Sox genes are HMG-domain containing transcription factors with important roles in developmental processes in animals; many of them appear to have conserved functions among eumetazoans. DemoSponges have fewer Sox genes than eumetazoans, but their roles remain unclear. The aim of this study is to gain insight into the early evolutionary history of the Sox gene family by identification and expression analysis of Sox genes in the Calcareous Sponge Sycon ciliatum. Calcaronean Sox related sequences were retrieved by searching recently generated genomic and transcriptome sequence resources and analyzed using variety of phylogenetic methods and identification of conserved motifs. Expression was studied by whole mount in situ hybridization. We have identified seven Sox genes and four Sox-related genes in the complete genome of Sycon ciliatum. Phylogenetic and conserved motif analyses showed that five of Sycon Sox genes represent groups B, C, E, and F present in cnidarians and bilaterians. Two additional genes are classified as Sox genes but cannot be assigned to specific subfamilies, and four genes are more similar to Sox genes than to other HMG-containing genes. Thus, the repertoire of Sox genes is larger in this representative of Calcareous Sponges than in the demoSponge Amphimedon queenslandica. It remains unclear whether this is due to the expansion of the gene family in Sycon or a secondary reduction in the Amphimedon genome. In situ hybridization of Sycon Sox genes revealed a variety of expression patterns during embryogenesis and in specific cell types of adult Sponges. In this study, we describe a large family of Sox genes in Sycon ciliatum with dynamic expression patterns, indicating that Sox genes are regulators in development and cell type determination in Sponges, as observed in higher animals. The revealed differences between demoSponge and calciSponge Sox genes repertoire highlight the need to utilize models representing different Sponge lineages to describe Sponge development, a prerequisite for deciphering evolution of metazoan developmental mechanisms.
Gert Wörheide - One of the best experts on this subject based on the ideXlab platform.
-
carbonic anhydrases an ancient tool in Calcareous Sponge biomineralization
Frontiers in Genetics, 2021Co-Authors: Oliver Voigt, Benedetta Fradusco, Carolin Gut, Charalampos Kevrekidis, Sergio Vargas, Gert WörheideAbstract:Enzymes of the α-carbonic anhydrase gene family (CAs) are essential for the deposition of calcium carbonate biominerals. In Calcareous Sponges (phylum Porifera, class Calcarea), specific CAs are involved in the formation of calcite spicules, a unique trait and synapomorphy of this class. However, detailed studies on the CA repertoire of Calcareous Sponges exist for only two species of one of the two Calcarea subclasses, the Calcaronea. The CA repertoire of the second subclass, the Calcinea, has not been investigated so far, leaving a considerable gap in our knowledge about this gene family in Calcarea. Here, using transcriptomic analysis, phylogenetics, and in situ hybridization, we study the CA repertoire of four additional species of Calcareous Sponges, including three from the previously unsampled subclass Calcinea. Our data indicate that the last common ancestor of Calcarea had four ancestral CAs with defined subcellular localizations and functions (mitochondrial/cytosolic, membrane-bound, and secreted non-catalytic). The evolution of membrane-bound and secreted CAs involved gene duplications and losses, whereas mitochondrial/cytosolic and non-catalytic CAs are evidently orthologous genes. Mitochondrial/cytosolic CAs are biomineralization-specific genes recruited for biomineralization in the last common ancestor of Calcareous Sponges. The spatial-temporal expression of these CAs differs between species, which may reflect differences between subclasses or be related to the secondary thickening of spicules during biomineralization that does not occur in all species. With this study, we extend the understanding of the role and the evolution of a key biomineralization gene in Calcareous Sponges.
-
a new species of the Calcareous Sponge genus leuclathrina calcarea calcinea clathrinida from the maldives
Zootaxa, 2018Co-Authors: Oliver Voigt, Benedetta Fradusco, Bernhard Ruthensteiner, Laura Leiva, Gert WörheideAbstract:The diversity and phylogenetic relationships of Calcareous Sponges are still not completely understood. Recent integrative approaches combined analyses of DNA and morphological observations. Such studies resulted in severe taxonomic revisions within the subclass Calcinea and provided the foundation for a phylogenetically meaningful classification. However, several genera are missing from DNA phylogenies and their relationship to other Calcinea remain uncertain. One of these genera is Leuclathrina (family Leucaltidae) . We here describe a new species from the Maldives, Leuclathrina translucida sp. nov., which is only the second species of the genus. Like the type species Leuclathrina asconoides, the new species has a leuconoid aquiferous system and lacks a specialized choanoskeleton. Phylogenetic analyses of the partial 28S ribosomal RNA gene revealed that L. translucida sp. nov. is most closely related to a clade containing the exclusively asconoid genera Ascandra , Levinella and Soleneiscus , and to a clade of the likewise asconoid genus Ernstia . No close relationship exists to other members of the polyphyletic family Leucaltidae, or to any other leuconoid Calcinea. Our results suggest that the leuconoid aquiferous system of Leuclathrina evolved independently from that of other calcineans and that the family assignment of the genus has to be reconsidered. Because the latter requires a more comprehensive family level revision among many genera of Calcinea, we propose to formally retain the genus in Leucaltidae for the time being.
-
structure and composition of Calcareous Sponge spicules a review and comparison to structurally related biominerals
Micron, 2008Co-Authors: Ingo Sethmann, Gert WörheideAbstract:Abstract Since the early 19th century, the skeletons of Calcareous Sponges (Porifera: Calcarea) with their mineralized spicules have been investigated for their morphologies, structures, and mineralogical and organic compositions. These biomineral spicules, up to about 10 mm in size, with one to four rays called actines, have various specific shapes and consist mainly of magnesium-calcite: in only one case has an additional phase of stabilized amorphous CaCO 3 (ACC) been discovered. The spicules are invariably covered by a thin organic sheath and display a number of intriguing properties. Despite their complex morphologies and rounded surfaces without flat crystal faces they behave largely as single crystal individuals of calcite, and to some degree crystallographic orientation is related to morphology. Despite their single-crystalline nature, most spicules show nearly isotropic fracture behaviour, not typical for calcite crystals, indicating enhanced fracture resistance. These unusual morphological and mechanical properties are the result of their mechanism of growth. Each spicule is formed by specialized cells (sclerocytes) that supply mineral ions or particles associated by organic macromolecules to extracellular cavities, where assembly and crystallization in alignment with an initial seed crystal (nucleus) takes place. As a result of discontinuous mineral deposition, cross-sections of larger spicules display concentric layering that mantles a central calcitic rod. On a smaller scale, the entire spicule displays a ‘nano-cluster’ structure with crystallographically aligned and putatively semicoherent crystal domains as well as a dispersed organic matrix intercalated between domain boundaries. This ultrastructure dissipates mechanical stress and deflects propagating fractures. Additionally, this nano-cluster construction, probably induced by intercalated organic substances, enables the formation of complex crystal morphologies independent of crystal faces. In this review, the current knowledge about the structure, composition, and formation of Calcareous Sponge spicules is summarised and discussed. Comparisons of Calcareous Sponge spicules with the amorphous silica spicules of Sponges of the classes Hexactinellida and Demospongiae, as well as with calcitic skeletal elements of echinoderms are drawn. Despite the variety of poriferan spicule mineralogy and the distant phylogenetic relationship between Sponges and echinoderms, all of these biominerals share similarities regarding their nano-scale construction. Furthermore, echinoderm skeletal elements resemble Calcareous Sponge spicules in that they represent magnesium-bearing calcite single-crystals with extremely complex morphologies.
-
phylogeography of western pacific leucetta chagosensis porifera calcarea from ribosomal dna sequences implications for population history and conservation of the great barrier reef world heritage area australia
Molecular Ecology, 2002Co-Authors: Gert Wörheide, John N A Hooper, Bernard M DegnanAbstract:Leucetta ‘chagosensis’ is a widespread Calcareous Sponge, occurring in shaded habitats of Indo-Pacific coral reefs. In this study we explore relationships among 19 ribosomal DNA sequence types (the ITS1-5.8S–ITS2 region plus flanking gene sequences) found among 54 individuals from 28 locations throughout the western Pacific, with focus on the Great Barrier Reef (GBR). Maximum parsimony analysis revealed phylogeographical structuring into four major clades (although not highly supported by bootstrap analysis) corresponding to the northern/central GBR with Guam and Taiwan, the southern GBR and subtropical regions south to Brisbane, Vanuatu and Indonesia. Subsequent nested clade analysis (NCA) confirmed this structure with a probability of > 95%. After NCA of geographical distances, a pattern of range expansion from the internal Indonesian clade was inferred at the total cladogram level, as the Indonesian clade was found to be the internal and therefore oldest clade. Two distinct clades were found on the GBR, which narrowly overlap geographically in a line approximately from the Whitsunday Islands to the northern Swain Reefs. At various clade levels, NCA inferred that the northern GBR clade was influenced by past fragmentation and contiguous range expansion events, presumably during/after sea level low stands in the Pleistocene, after which the northern GBR might have been recolonized from the Queensland Plateau in the Coral Sea. The southern GBR clade is most closely related to subtropical L. ‘chagosensis’, and we infer that the southern GBR probably was recolonized from there after sea level low stands, based on our NCA results and supported by oceanographic data. Our results have important implications for conservation and management of the GBR, as they highlight the importance of marginal transition zones in the generation and maintenance of species rich zones, such as the Great Barrier Reef World Heritage Area.