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Calcarea

The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform

Gert Worheide – 1st expert on this subject based on the ideXlab platform

  • a short lsu rrna fragment as a standard marker for integrative taxonomy in calcareous sponges porifera Calcarea
    Organisms Diversity & Evolution, 2016
    Co-Authors: Oliver Voigt, Gert Worheide

    Abstract:

    Calcareous sponges are taxonomically difficult, and their morpho-systematic classification often conflicts with molecular phylogenies. Consequently, species descriptions that rely solely on morphological characters,and taxonomic revisions appear to provide little to no information about phylogenetic affiliations and integrative approaches, combining DNA and morphological data, are applied more frequently. However, a standardized database that combines DNA sequence and morphological specimen information is still missing for calcareous sponges. The mitochondrial cytochrome oxidase subunit 1 gene (COI) is the marker of choice for rapid species identification in many other animal taxa, including demosponges, for which COI sequences and morphological information have been compiled in the sponge barcoding database (www.spongebarcoding.org). But due to the peculiarities of Calcarean mitochondrial genomes, sequencing COI in Calcarea is methodologically challenging. We here propose the use of one more commonly used DNA marker, the C-region of the 28S gene (LSU), as standard barcoding marker for Calcarea, after also considering the internal transcribed spacer (ITS) region for such proposes. Especially in the subclass Calcaronea, we observed severe problems of high intra- and intergenomic variation that impedes pan-Calcarean ITS alignments. In contrast, the C-region of LSU provides a short but phylogenetically informative DNA sequence, alignable across both subclasses with the help of a newly developed secondary structure and which also can be used to address exemplary taxonomic questions. With our work, we start to close the gap of Calcarea in the sponge barcoding project (www.spongebarcoding.org) and provide a resource for biodiversity studies and potentially for DNA-guided species identification.

  • first evaluation of mitochondrial dna as a marker for phylogeographic studies of Calcarea a case study from leucetta chagosensis
    Hydrobiologia, 2012
    Co-Authors: Oliver Voigt, Vincent Eichmann, Gert Worheide

    Abstract:

    In most animals mitochondrial DNA (mtDNA) evolves much faster than nuclear DNA. Therefore, and because of its shorter coalescent time, mitochondrial (mt) markers provide better resolution to trace more recent evolutionary events compared to nuclear DNA. But in contrast to most other Metazoa, previous studies suggested that in sponges mitochondrial sequence evolution is much slower, making mtDNA less suitable for studies at the intraspecific level. However, these observations were made in the class Demospongiae and so far no data exist for calcareous sponges (Class Calcarea). We here provide the first study that evaluates intraspecific mt sequence variation in Calcarea. We focus on arguably the best-studied species Leucetta chagosensis, for which three nuclear DNA marker datasets existed previously. We here sequenced the partial mitochondrial cytochrome oxidase subunit III gene (cox3). Our analyses reveal an unexpected variability of up to 8.5% in this mitochondrial marker. In contrast to other sponges where this marker evolves considerable slower than the nuclear internal transcribed spacer region (ITS), we found that cox3 in L. chagosensis evolves about five times as fast as ITS. The variability is similar to that of nuclear intron data of the species. The phylogeny inferred with cox3 is congruent with other markers, but separates earlier reported genetic groups much more distinctively than nuclear DNA. This provides further evidence for cryptic speciation in L. chagosensis. All these features make Calcarean mtDNA exceptional among sponges and show its suitability for phylogeographic studies and potential as a species-specific (DNA barcoding) marker to distinguish morphologically identical cryptic species.

  • molecular phylogenetic evaluation of classification and scenarios of character evolution in calcareous sponges porifera class Calcarea
    PLOS ONE, 2012
    Co-Authors: Oliver Voigt, Eilika Wulfing, Gert Worheide

    Abstract:

    Calcareous sponges (Phylum Porifera, Class Calcarea) are known to be taxonomically difficult. Previous molecular studies have revealed many discrepancies between classically recognized taxa and the observed relationships at the order, family and genus levels; these inconsistencies question underlying hypotheses regarding the evolution of certain morphological characters. Therefore, we extended the available taxa and character set by sequencing the complete small subunit (SSU) rDNA and the almost complete large subunit (LSU) rDNA of additional key species and complemented this dataset by substantially increasing the length of available LSU sequences. Phylogenetic analyses provided new hypotheses about the relationships of Calcarea and about the evolution of certain morphological characters. We tested our phylogeny against competing phylogenetic hypotheses presented by previous classification systems. Our data reject the current order-level classification by again finding non-monophyletic Leucosolenida, Clathrinida and Murrayonida. In the subclass Calcinea, we recovered a clade that includes all species with a cortex, which is largely consistent with the previously proposed order Leucettida. Other orders that had been rejected in the current system were not found, but could not be rejected in our tests either. We found several additional families and genera polyphyletic: the families Leucascidae and Leucaltidae and the genus Leucetta in Calcinea, and in Calcaronea the family Amphoriscidae and the genus Ute. Our phylogeny also provided support for the vaguely suspected close relationship of several members of Grantiidae with giantortical diactines to members of Heteropiidae. Similarly, our analyses revealed several unexpected affinities, such as a sister group relationship between Leucettusa (Leucaltidae) and Leucettidae and between Leucascandra (Jenkinidae) and Sycon carteri (Sycettidae). According to our results, the taxonomy of Calcarea is in desperate need of a thorough revision, which cannot be achieved by considering morphology alone or relying on a taxon sampling based on the current classification below the subclass level.

Michelle Klautau – 2nd expert on this subject based on the ideXlab platform

  • the new sponge species amphoriscus pedunculatus porifera Calcarea
    Zootaxa, 2017
    Co-Authors: Michelle Klautau, Fernanda F Cavalcanti, Radovan Borojevic

    Abstract:

    Amphoriscus is a widespread genus with 17 species. A new species was found in SE Brazil and it represents the second species of this genus in Brazilian waters. Amphoriscus pedunculatus sp. nov. has a special structure, a peduncle, to attach to the substrate. Special attachment structures are not very common in the class Calcarea but this is the third species of the genus with a peduncle. Besides peduncle, another attachment structure found in some species of Amphoriscus is the root-tuft, an attachment structure composed of diactines and anchor-like triactines or tetractines. The evolution of these attachment structures in Amphoriscus is not known but they have also been found out of this genus, suggesting that these structures appeared several times during the evolution of Calcarea or that species currently classified in different genera are in fact congeneric.

  • new leucettidae de laubenfels 1936 porifera Calcarea from western australia
    Zootaxa, 2016
    Co-Authors: Pedro Leocorny, Aline Alencar, Jane Fromont, Michelle Klautau

    Abstract:

    This paper reports four new Leucettidae (Porifera, Calcarea) from Western Australia, with two representatives of Leucetta and two of Pericharax : L. foliata sp. nov., L . purpurea sp. nov., Pericharax crypta sp. nov., and P. vallii sp. nov. This is the first time tripods have been described within Pericharax . In addition, one species ( L . foliata sp. nov.) has an external morphology not previously reported for Leucetta , and for the first time tetractines of the inhalant and exhalant canals have been distinguished. Leucettidae now comprises 28 species, eight of them occur in Western Australia, which means this Australian State has the highest species richness for this family in Australia. The WA coastline has been largely unexplored for Calcarea so it is likely that further collecting will yield additional species. Leucetta microraphis is the most widespread species of Leucettidae in Australia, occurring in all States except the Northern Territory and Tasmania. We highlight the importance of a revision of the Leucettidae using molecular and morphological characters to determine which morphological characters have a phylogenetic signal.

  • fragmentation fusion and genetic homogeneity in a calcareous sponge porifera Calcarea
    Journal of Experimental Zoology, 2016
    Co-Authors: Andre Padua, Pedro Leocorny, Marcio R Custodio, Michelle Klautau

    Abstract:

    Sessile marine invertebrates living on hard substrata usually present strategies such as size variations, longer life spans, fragmentation and fusion to occupy and compete for space. Calcareous sponges are usually small and short-lived, and some species are known to undergo frequent fragmentation and fusion events. However, whether fusion occurs only between genetically identical individuals remains unclear. We investigated the occurrence of chimaeras in the calcareous sponge Clathrina aurea by following the dynamics of fragmentation and fusion of 66 individuals in the field for up to 18 months and determined size variations and the life span of each individual. Microsatellites were used to determine whether fusion events occur among genetically different individuals. Growth and shrinkage of individuals were frequently observed, showing that size cannot be associated with age in C. aurea. The life span of the species ranged from 1 to 16 months (mean: 4.7 months). Short life spans and variable growth rates have been observed in other species of the class Calcarea. Fragmentation and fusion events were observed, but fusion events always occurred between genetically identical individuals, as has been suggested by graft experiments in adult Demospongiae and other Calcarea. These results suggest that at least C. aurea adults may have some mechanism to avoid chimaerism.

Oliver Voigt – 3rd expert on this subject based on the ideXlab platform

  • a short lsu rrna fragment as a standard marker for integrative taxonomy in calcareous sponges porifera Calcarea
    Organisms Diversity & Evolution, 2016
    Co-Authors: Oliver Voigt, Gert Worheide

    Abstract:

    Calcareous sponges are taxonomically difficult, and their morpho-systematic classification often conflicts with molecular phylogenies. Consequently, species descriptions that rely solely on morphological characters,and taxonomic revisions appear to provide little to no information about phylogenetic affiliations and integrative approaches, combining DNA and morphological data, are applied more frequently. However, a standardized database that combines DNA sequence and morphological specimen information is still missing for calcareous sponges. The mitochondrial cytochrome oxidase subunit 1 gene (COI) is the marker of choice for rapid species identification in many other animal taxa, including demosponges, for which COI sequences and morphological information have been compiled in the sponge barcoding database (www.spongebarcoding.org). But due to the peculiarities of Calcarean mitochondrial genomes, sequencing COI in Calcarea is methodologically challenging. We here propose the use of one more commonly used DNA marker, the C-region of the 28S gene (LSU), as standard barcoding marker for Calcarea, after also considering the internal transcribed spacer (ITS) region for such proposes. Especially in the subclass Calcaronea, we observed severe problems of high intra- and intergenomic variation that impedes pan-Calcarean ITS alignments. In contrast, the C-region of LSU provides a short but phylogenetically informative DNA sequence, alignable across both subclasses with the help of a newly developed secondary structure and which also can be used to address exemplary taxonomic questions. With our work, we start to close the gap of Calcarea in the sponge barcoding project (www.spongebarcoding.org) and provide a resource for biodiversity studies and potentially for DNA-guided species identification.

  • first evaluation of mitochondrial dna as a marker for phylogeographic studies of Calcarea a case study from leucetta chagosensis
    Hydrobiologia, 2012
    Co-Authors: Oliver Voigt, Vincent Eichmann, Gert Worheide

    Abstract:

    In most animals mitochondrial DNA (mtDNA) evolves much faster than nuclear DNA. Therefore, and because of its shorter coalescent time, mitochondrial (mt) markers provide better resolution to trace more recent evolutionary events compared to nuclear DNA. But in contrast to most other Metazoa, previous studies suggested that in sponges mitochondrial sequence evolution is much slower, making mtDNA less suitable for studies at the intraspecific level. However, these observations were made in the class Demospongiae and so far no data exist for calcareous sponges (Class Calcarea). We here provide the first study that evaluates intraspecific mt sequence variation in Calcarea. We focus on arguably the best-studied species Leucetta chagosensis, for which three nuclear DNA marker datasets existed previously. We here sequenced the partial mitochondrial cytochrome oxidase subunit III gene (cox3). Our analyses reveal an unexpected variability of up to 8.5% in this mitochondrial marker. In contrast to other sponges where this marker evolves considerable slower than the nuclear internal transcribed spacer region (ITS), we found that cox3 in L. chagosensis evolves about five times as fast as ITS. The variability is similar to that of nuclear intron data of the species. The phylogeny inferred with cox3 is congruent with other markers, but separates earlier reported genetic groups much more distinctively than nuclear DNA. This provides further evidence for cryptic speciation in L. chagosensis. All these features make Calcarean mtDNA exceptional among sponges and show its suitability for phylogeographic studies and potential as a species-specific (DNA barcoding) marker to distinguish morphologically identical cryptic species.

  • molecular phylogenetic evaluation of classification and scenarios of character evolution in calcareous sponges porifera class Calcarea
    PLOS ONE, 2012
    Co-Authors: Oliver Voigt, Eilika Wulfing, Gert Worheide

    Abstract:

    Calcareous sponges (Phylum Porifera, Class Calcarea) are known to be taxonomically difficult. Previous molecular studies have revealed many discrepancies between classically recognized taxa and the observed relationships at the order, family and genus levels; these inconsistencies question underlying hypotheses regarding the evolution of certain morphological characters. Therefore, we extended the available taxa and character set by sequencing the complete small subunit (SSU) rDNA and the almost complete large subunit (LSU) rDNA of additional key species and complemented this dataset by substantially increasing the length of available LSU sequences. Phylogenetic analyses provided new hypotheses about the relationships of Calcarea and about the evolution of certain morphological characters. We tested our phylogeny against competing phylogenetic hypotheses presented by previous classification systems. Our data reject the current order-level classification by again finding non-monophyletic Leucosolenida, Clathrinida and Murrayonida. In the subclass Calcinea, we recovered a clade that includes all species with a cortex, which is largely consistent with the previously proposed order Leucettida. Other orders that had been rejected in the current system were not found, but could not be rejected in our tests either. We found several additional families and genera polyphyletic: the families Leucascidae and Leucaltidae and the genus Leucetta in Calcinea, and in Calcaronea the family Amphoriscidae and the genus Ute. Our phylogeny also provided support for the vaguely suspected close relationship of several members of Grantiidae with giantortical diactines to members of Heteropiidae. Similarly, our analyses revealed several unexpected affinities, such as a sister group relationship between Leucettusa (Leucaltidae) and Leucettidae and between Leucascandra (Jenkinidae) and Sycon carteri (Sycettidae). According to our results, the taxonomy of Calcarea is in desperate need of a thorough revision, which cannot be achieved by considering morphology alone or relying on a taxon sampling based on the current classification below the subclass level.