The Experts below are selected from a list of 10560 Experts worldwide ranked by ideXlab platform
Laura A. Katz - One of the best experts on this subject based on the ideXlab platform.
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Are Microbes Fundamentally Different Than Macroorganisms? Convergence and a Possible Case for Neutral Phenotypic Evolution in Testate Amoeba (Amoebozoa: Arcellinida)
Royal Society open science, 2015Co-Authors: Angela M. Oliverio, Daniel J. G. Lahr, Jessica R. Grant, Laura A. KatzAbstract:This study reveals extensive phenotypic convergence based on the non-monophyly of genera and Morphospecies of testate (shelled) amoebae. Using two independent markers, small subunit ribosomal DNA (ssu-rDNA) and mitochondrial cytochrome oxidase I (COI), we demonstrate discordance between morphology and molecules for 'core Nebela' species (Arcellinida; Amoebozoa). Prior work using just a single locus, ssu-rDNA, also supported the non-monophyly of the genera Hyalosphenia and Nebela as well as for several Morphospecies within these genera. Here, we obtained COI gene sequences of 59 specimens from seven Morphospecies and ssu-rDNA gene sequences of 50 specimens from six Morphospecies of hyalosphenids. Our analyses corroborate the prior ssu-rDNA findings of morphological convergence in test (shell) morphologies, as COI and ssu-rDNA phylogenies are concordant. Further, the monophyly of Morphospecies is rejected using approximately unbiased tests. Given that testate amoebae are used as bioindicators in both palaeoecological and contemporary studies of threatened ecosystems such as bogs and fens, understanding the discordance between morphology and genetics in the hyalosphenids is essential for interpretation of indicator species. Further, while convergence is normally considered the result of natural selection, it is possible that neutrality underlies phenotypic evolution in these microorganisms.
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cryptic diversity within Morphospecies of testate amoebae amoebozoa arcellinida in new england bogs and fens
Protist, 2014Co-Authors: Angela M. Oliverio, Daniel J. G. Lahr, Laura A. Katz, Truc B NguyenAbstract:Testate (shelled) amoebae are abundant and diverse in Sphagnum-rich areas of bogs and fens. Test morphology is standardly used to identify Morphospecies as tests have varying shapes and compositions (e.g. siliceous, proteinaceous, agglutinated, or even calcareous). The recent application of molecular tools has revealed a greater complexity than morphology suggests, including multiple cryptic species. Here, we assess the biodiversity and relationships among eight Morphospecies: Hyalosphenia elegans, Hyalosphenia papilio, Nebela carinata, Nebela flabellulum, Nebela militaris, Nebela tincta, Nebela tubulosa, and Quadrulella symmetrica using small subunit ribosomal DNA (SSU-rDNA). An SSU-rDNA phylogeny including 20 specimens from GenBank and 63 from this study reveals diversity within and among Morphospecies and low resolution among some Nebela spp. Previous SSU-rDNA work on a limited sample of these species showed non-monophyly in the genus Hyalosphenia. Our analyses confirm this pattern and further suggest that other Nebela genera and Morphospecies are not monophyletic. Moreover, inclusion of up to 24 specimens per species indicates non-monophyly of the Morphospecies Hyalosphenia papilio and Hyalosphenia elegans. Our results suggest the morphological plasticity of testate amoebae across evolutionary time scales and that a combination of morphology and molecular analyses is needed to understand the biodiversity of these taxa.
Daniel J. G. Lahr - One of the best experts on this subject based on the ideXlab platform.
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Are Microbes Fundamentally Different Than Macroorganisms? Convergence and a Possible Case for Neutral Phenotypic Evolution in Testate Amoeba (Amoebozoa: Arcellinida)
Royal Society open science, 2015Co-Authors: Angela M. Oliverio, Daniel J. G. Lahr, Jessica R. Grant, Laura A. KatzAbstract:This study reveals extensive phenotypic convergence based on the non-monophyly of genera and Morphospecies of testate (shelled) amoebae. Using two independent markers, small subunit ribosomal DNA (ssu-rDNA) and mitochondrial cytochrome oxidase I (COI), we demonstrate discordance between morphology and molecules for 'core Nebela' species (Arcellinida; Amoebozoa). Prior work using just a single locus, ssu-rDNA, also supported the non-monophyly of the genera Hyalosphenia and Nebela as well as for several Morphospecies within these genera. Here, we obtained COI gene sequences of 59 specimens from seven Morphospecies and ssu-rDNA gene sequences of 50 specimens from six Morphospecies of hyalosphenids. Our analyses corroborate the prior ssu-rDNA findings of morphological convergence in test (shell) morphologies, as COI and ssu-rDNA phylogenies are concordant. Further, the monophyly of Morphospecies is rejected using approximately unbiased tests. Given that testate amoebae are used as bioindicators in both palaeoecological and contemporary studies of threatened ecosystems such as bogs and fens, understanding the discordance between morphology and genetics in the hyalosphenids is essential for interpretation of indicator species. Further, while convergence is normally considered the result of natural selection, it is possible that neutrality underlies phenotypic evolution in these microorganisms.
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cryptic diversity within Morphospecies of testate amoebae amoebozoa arcellinida in new england bogs and fens
Protist, 2014Co-Authors: Angela M. Oliverio, Daniel J. G. Lahr, Laura A. Katz, Truc B NguyenAbstract:Testate (shelled) amoebae are abundant and diverse in Sphagnum-rich areas of bogs and fens. Test morphology is standardly used to identify Morphospecies as tests have varying shapes and compositions (e.g. siliceous, proteinaceous, agglutinated, or even calcareous). The recent application of molecular tools has revealed a greater complexity than morphology suggests, including multiple cryptic species. Here, we assess the biodiversity and relationships among eight Morphospecies: Hyalosphenia elegans, Hyalosphenia papilio, Nebela carinata, Nebela flabellulum, Nebela militaris, Nebela tincta, Nebela tubulosa, and Quadrulella symmetrica using small subunit ribosomal DNA (SSU-rDNA). An SSU-rDNA phylogeny including 20 specimens from GenBank and 63 from this study reveals diversity within and among Morphospecies and low resolution among some Nebela spp. Previous SSU-rDNA work on a limited sample of these species showed non-monophyly in the genus Hyalosphenia. Our analyses confirm this pattern and further suggest that other Nebela genera and Morphospecies are not monophyletic. Moreover, inclusion of up to 24 specimens per species indicates non-monophyly of the Morphospecies Hyalosphenia papilio and Hyalosphenia elegans. Our results suggest the morphological plasticity of testate amoebae across evolutionary time scales and that a combination of morphology and molecular analyses is needed to understand the biodiversity of these taxa.
Angela M. Oliverio - One of the best experts on this subject based on the ideXlab platform.
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Are Microbes Fundamentally Different Than Macroorganisms? Convergence and a Possible Case for Neutral Phenotypic Evolution in Testate Amoeba (Amoebozoa: Arcellinida)
Royal Society open science, 2015Co-Authors: Angela M. Oliverio, Daniel J. G. Lahr, Jessica R. Grant, Laura A. KatzAbstract:This study reveals extensive phenotypic convergence based on the non-monophyly of genera and Morphospecies of testate (shelled) amoebae. Using two independent markers, small subunit ribosomal DNA (ssu-rDNA) and mitochondrial cytochrome oxidase I (COI), we demonstrate discordance between morphology and molecules for 'core Nebela' species (Arcellinida; Amoebozoa). Prior work using just a single locus, ssu-rDNA, also supported the non-monophyly of the genera Hyalosphenia and Nebela as well as for several Morphospecies within these genera. Here, we obtained COI gene sequences of 59 specimens from seven Morphospecies and ssu-rDNA gene sequences of 50 specimens from six Morphospecies of hyalosphenids. Our analyses corroborate the prior ssu-rDNA findings of morphological convergence in test (shell) morphologies, as COI and ssu-rDNA phylogenies are concordant. Further, the monophyly of Morphospecies is rejected using approximately unbiased tests. Given that testate amoebae are used as bioindicators in both palaeoecological and contemporary studies of threatened ecosystems such as bogs and fens, understanding the discordance between morphology and genetics in the hyalosphenids is essential for interpretation of indicator species. Further, while convergence is normally considered the result of natural selection, it is possible that neutrality underlies phenotypic evolution in these microorganisms.
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cryptic diversity within Morphospecies of testate amoebae amoebozoa arcellinida in new england bogs and fens
Protist, 2014Co-Authors: Angela M. Oliverio, Daniel J. G. Lahr, Laura A. Katz, Truc B NguyenAbstract:Testate (shelled) amoebae are abundant and diverse in Sphagnum-rich areas of bogs and fens. Test morphology is standardly used to identify Morphospecies as tests have varying shapes and compositions (e.g. siliceous, proteinaceous, agglutinated, or even calcareous). The recent application of molecular tools has revealed a greater complexity than morphology suggests, including multiple cryptic species. Here, we assess the biodiversity and relationships among eight Morphospecies: Hyalosphenia elegans, Hyalosphenia papilio, Nebela carinata, Nebela flabellulum, Nebela militaris, Nebela tincta, Nebela tubulosa, and Quadrulella symmetrica using small subunit ribosomal DNA (SSU-rDNA). An SSU-rDNA phylogeny including 20 specimens from GenBank and 63 from this study reveals diversity within and among Morphospecies and low resolution among some Nebela spp. Previous SSU-rDNA work on a limited sample of these species showed non-monophyly in the genus Hyalosphenia. Our analyses confirm this pattern and further suggest that other Nebela genera and Morphospecies are not monophyletic. Moreover, inclusion of up to 24 specimens per species indicates non-monophyly of the Morphospecies Hyalosphenia papilio and Hyalosphenia elegans. Our results suggest the morphological plasticity of testate amoebae across evolutionary time scales and that a combination of morphology and molecular analyses is needed to understand the biodiversity of these taxa.
Viviana A Alder - One of the best experts on this subject based on the ideXlab platform.
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utility of genetic markers and morphology for species discrimination within the order tintinnida ciliophora spirotrichea
Protist, 2013Co-Authors: Luciana F Santoferrara, George B Mcmanus, Viviana A AlderAbstract:We evaluated the small- and large-subunit rDNA (SSU and LSU, respectively) for their ability to discriminate Morphospecies of tintinnid ciliates. Multiple individuals from 29 Morphospecies were identified according to microscopically-observed characteristics of the lorica, and then sequenced for both loci (21 new species for SSU and all of them new for LSU). Sequences from public databases were included in our analyses, and two hypervariable SSU regions (V4 and V9) were separately examined. Of the four regions, LSU is the most useful as a potential barcoding tool. It showed a gap in distances within and between species, and discriminated the maximum number of phylotypes (86% at 1% cut-off). SSU and V4 were less consistent, sometimes lumping together very distinctive Morphospecies, even at the 1% level of sequence divergence. V9 was the least reliable marker in delimitating Morphospecies. The agreement in sequences and morphology suggests that the lorica is useful for species discrimination, even in agglomerated forms. However, the observation of both genetically constant yet polymorphic groups of species, as well as similar Morphospecies with divergent sequences, indicates that previous taxonomic schemes are complementary to the emerging molecular database.
Robin B Gasser - One of the best experts on this subject based on the ideXlab platform.
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genetic variation within and among species of cloacina strongyloidea cloacinine from the swamp wallaby wallabia bicolor marsupialia macropodidae
Infection Genetics and Evolution, 2014Co-Authors: Mary Shuttleworth, Ian Beveridge, Robin B Gasser, Neil B Chilton, Anson V Koehler, Abdul JabbarAbstract:This study examined genetic variation within and among species of Cloacina found in the swamp wallaby (Wallabia bicolor) collected at different localities along the eastern coast of Australia, and evaluated geographical distance as a potential driver for genetic variation. The first and second internal transcribed spacers (ITS-1 and ITS-2, respectively) of the nuclear ribosomal DNA were used to characterize individuals of 11 Morphospecies of Cloacina that parasitize W. bicolor. The results of the molecular analyses revealed multiple genotypes for the nine Morphospecies of Cloacina (i.e. Cloacina annulata, Cloacina edwardsi, Cloacina eos, Cloacina gallardi, Cloacina mawsonae, Cloacina papillata, Cloacina papillatissima, Cloacina pollux, and Cloacina wallabiae) for which multiple individuals were available for analysis. However, phylogenetic analyses of the sequence data revealed that for each Morphospecies, there was no subdivision of individuals into distinct clades based on geographical region from which they were collected. Additional studies are needed to determine the drivers of genetic variation in cloacinid nematodes, and hence increase our understanding of the diversity of parasitic nematodes in macropodid marsupials.
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genetic variation within species of the nematode genus cloacina strongyloidea cloacininae parasitic in the stomachs of rock wallabies petrogale spp marsupialia macropodidae in queensland
Australian Journal of Zoology, 2009Co-Authors: Ian Beveridge, Neil B Chilton, Florence Hubychilton, Peter M Johnson, Robin B GasserAbstract:Four Morphospecies of Cloacina, parasitic nematodes in the stomachs of rock wallabies (Petrogale spp.) from Queensland, were compared genetically using sequence data of the two internal transcribed spacers of nuclear ribosomal DNA (rDNA). The results suggest that two geographically isolated populations of C. ernabella from P. purpureicollis were genetically distinct. Based on the autapomorphic species concept, these two C. ernabella populations represented different species. For the three other nematode Morphospecies, there were genetic differences among individuals of a Morphospecies present in different species of host. The results suggest that each may represent a complex of sibling species, with a different species present in each species of rock wallaby examined for that Morphospecies. In the C. caenis and C. pearsoni complexes, the lineage present in P. purpureicollis from western Queensland represents a sister taxon to those in the P. pencillata complex from the east coast. In the C. robertsi complex, the taxon parasitic in P. persephone represents the sister taxon to those in the P. pencillata complex and in P. purpureicollis. C. robertsi was found for the first time in P. purpureicollis from Winton in central Queensland, suggesting contact in the recent past between populations of P. purpureicollis and a member of the P. penicillata complex.
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mitochondrial dna polymorphism within and among species of capillaria sensu lato from australian marsupials and rodents
International Journal for Parasitology, 2000Co-Authors: Xingquan Zhu, David M Spratt, Ian Beveridge, Peter Haycock, Robin B GasserAbstract:The nucleotide variation in a mitochondrial DNA (mtDNA) fragment within and among species of Capillaria sensu lato from Australian marsupials and rodents was analyzed using a mutation scanning/sequencing approach. The fragment of the cytochrome c oxidase subunit I (COI) was amplified by PCR from parasite DNA, and analysed by single-strand conformation polymorphism (SSCP) and sequencing. There was no significant variation in SSCP profiles within a Morphospecies from a particular host species, but significant variation existed among Morphospecies originating from different host species. The same Morphospecies was found to occur in 1-3 tissue habitats within one host individual or within different individuals of a particular species of host from the same or different geographical areas, and Morphospecies appeared to be relatively host specific at the generic level. The results indicated that the species of Capillaria sensu lato examined, although highly variable in their host and tissue specificity, may exhibit the greatest degree of specificity at the level of host genus.
