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Verheye ML, D’Udekem D’Acoz C. Integrative taxonomy of giant crested Eusirus in the Southern Ocean, including the description of a new species (Crustacea: Amphipoda: Eusiridae). Zool J Linn Soc 2020. [DOI: 10.1093/zoolinnean/zlaa141] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Among Antarctic amphipods of the genus Eusirus, a highly distinctive clade of giant species is characterized by a dorsal, blade-shaped tooth on pereionites 5–7 and pleonites 1–3. This lineage, herein named ‘crested Eusirus’, includes two potential species complexes, the Eusirus perdentatus and Eusirus giganteus complexes, in addition to the more distinctive Eusirus propeperdentatus. Molecular phylogenies and statistical parsimony networks (COI, CytB and ITS2) of crested Eusirus are herein reconstructed. This study aims to formally revise species diversity within crested Eusirus by applying several species delimitation methods (Bayesian implementation of the Poisson tree processes model, general mixed Yule coalescent, multi-rate Poisson tree processes and automatic barcode gap discovery) on the resulting phylogenies. In addition, results from the DNA-based methods are benchmarked against a detailed morphological analysis of all available specimens of the E. perdentatus complex. Our results indicate that species diversity of crested Eusirus is underestimated. Overall, DNA-based methods suggest that the E. perdentatus complex is composed of three putative species and that the E. giganteus complex includes four or five putative species. The morphological analysis of available specimens from the E. perdentatus complex corroborates molecular results by identifying two differentiable species, the genuine E. perdentatus and a new species, herein described as Eusirus pontomedon sp. nov.
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Affiliation(s)
- Marie L Verheye
- Royal Belgian Institute of Natural Sciences, O.D. Nature, Rue Vautier, Brussels, Belgium
- Université de Liège, Laboratoire d’Océanologie, Quartier Agora, Allée du 6 Août, Liège, Belgium
| | - Cédric D’Udekem D’Acoz
- Royal Belgian Institute of Natural Sciences, O.D. Nature, Rue Vautier, Brussels, Belgium
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2
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Lopes EM, Ventura CRR. Development of the Sea Star Echinaster (Othilia) brasiliensis, with Inference on the Evolution of Development and Skeletal Plates in Asteroidea. THE BIOLOGICAL BULLETIN 2016; 230:25-34. [PMID: 26896175 DOI: 10.1086/bblv230n1p25] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We describe the development and juvenile morphology of the sea star Echinaster (Othilia) brasiliensis in order to explore evolutionary developmental modes and skeletal homologies. This species produces large, buoyant eggs (0.6 ± 0.03 mm diameter), and has a typical lecithotrophic brachiolaria larva. The planktonic brachiolaria larva is formed 2-4 days after fertilization, when cilia cover the surface. Early juveniles are completely formed by 18 days of age. Initial growth is supported by maternal nutrients while the stomach continues to develop until 60 days after fertilization, when juveniles reach about 0.5 mm of radius length. The madreporite was observed 88 days after fertilization. In the youngest juvenile skeleton of E. (O.) brasiliensis, the madreporite and odontophore are homologous to those of other recent, non-paxillosid asteroids, and follow the Late Madreporic Mode. The emergence of plates related to the ambulacral system follows the Ocular Plate Rule. The development and juvenile skeletal morphology of this species are similar to those of the few other studied species in the genus Echinaster. This study corroborates the notion that the mode of development--including a short-lived lecithotrophic brachiolaria larva--in all Echinaster species shares a similar pattern that may be conserved throughout the evolutionary history of the group.
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Affiliation(s)
- Elinia Medeiros Lopes
- Biodiversity and Evolutionary Biology Graduate Program of the Federal University of Rio de Janeiro, 21941-901, Rio de Janeiro, RJ, Brazil; and Departamento de Invertebrados, Laboratório de Echinodermata, Museu Nacional/Universidade Federal do Rio de Janeiro (UFRJ), Quinta da Boa Vista, s/no, São Cristóvão, 20940-040, Rio de Janeiro, RJ, Brazil
| | - Carlos Renato Rezende Ventura
- Departamento de Invertebrados, Laboratório de Echinodermata, Museu Nacional/Universidade Federal do Rio de Janeiro (UFRJ), Quinta da Boa Vista, s/no, São Cristóvão, 20940-040, Rio de Janeiro, RJ, Brazil
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3
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Morphological and genetic analyses reveal a cryptic species complex in the echinoid Echinocardium cordatum and rule out a stabilizing selection explanation. Mol Phylogenet Evol 2016; 94:207-20. [DOI: 10.1016/j.ympev.2015.07.023] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 07/22/2015] [Accepted: 07/27/2015] [Indexed: 12/30/2022]
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Payne RP, Griffiths CL, von der Heyden S, Koch E. The cushion-star Parvulastra exigua in South Africa: one species or more? Zookeys 2015:1-16. [PMID: 26478703 PMCID: PMC4602288 DOI: 10.3897/zookeys.524.6145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 09/06/2015] [Indexed: 11/18/2022] Open
Abstract
The cushion–star Parvulastraexigua (Lamarck, 1816) is a widely distributed member of the temperate intertidal fauna in the southern hemisphere. In South Africa, it occurs in sympatry with the endemic Parvulastradyscrita (Clark, 1923), the two species being differentiated predominantly by gonopore placement. Several recent studies have suggested that there may be additional cryptic species within the Parvulastraexigua complex in South Africa, based variously on color morphology, genetic evidence and the differential placement of the gonopores. This paper attempts to resolve whether one or more species are represented within Parvulastraexigua. A total of 346 Parvulastraexigua and 8 Parvulastradyscrita were collected from sites on the west and south–west coasts of South Africa; morphological, anatomical and genetic analyses were performed to determine whether cryptic species and/or Parvulastraexigua specimens with aboral gonopores were present. Results show that neither cryptic species nor Parvulastraexigua specimens with aboral gonopores occur at these sites. This study thus refutes previous claims of the existence of aboral gonopores in South African Parvulastraexigua, and suggests that a single species is represented. The distinction between Parvulastraexigua and Parvulastradyscrita is also confirmed, and features separating these two species are clarified and documented.
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Affiliation(s)
- Robyn P Payne
- Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa ; Marine Research Institute, University of Cape Town, Private Bag X3, Rondebosch 7701, Cape Town, South Africa ; Present address: Department of Biodiversity and Conservation Biology, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa
| | - Charles L Griffiths
- Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa ; Marine Research Institute, University of Cape Town, Private Bag X3, Rondebosch 7701, Cape Town, South Africa
| | - Sophie von der Heyden
- Evolutionary Genomics Group, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Erich Koch
- Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa ; Marine Research Institute, University of Cape Town, Private Bag X3, Rondebosch 7701, Cape Town, South Africa
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Weber AAT, Stöhr S, Chenuil A. Genetic data, reproduction season and reproductive strategy data support the existence of biological species in Ophioderma longicauda. C R Biol 2014; 337:553-60. [PMID: 25282170 DOI: 10.1016/j.crvi.2014.07.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 07/23/2014] [Accepted: 07/24/2014] [Indexed: 11/30/2022]
Abstract
Cryptic species are numerous in the marine environment. The brittle star Ophioderma longicauda is composed of six mitochondrial lineages, encompassing brooders, which form a monophyletic group, and broadcasters, from which the brooders are derived. To clarify the species limits within O. longicauda, we compared the reproductive status of the sympatric lineages L1 and L3 (defined after sequencing a portion of the mitochondrial gene COI) during the month of May in Greece. In addition, we genotyped a nuclear marker, intron i51. Each L3 female was brooding, whereas all L1 specimens displayed full gonads, suggesting temporal pre-zygotic isolation between brooders and broadcasters. Statistical differences were found among lineages in morphology and bathymetric distribution. Finally, the intron i51 was polymorphic in L1 (60 individuals), but monomorphic in L3 (109 individuals), confirming the absence of gene flow between brooders and broadcasters. In conclusion, the broadcasting lineage L1 and the brooding lineage L3 are different biological species.
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Affiliation(s)
- Alexandra Anh-Thu Weber
- Aix-Marseille Université, Institut méditerranéen de biodiversité et d'écologie marine et continentale (IMBE), CNRS - IRD - UAPV, station marine d'Endoume, chemin de la Batterie-des-Lions, 13007 Marseille, France.
| | - Sabine Stöhr
- Department of Zoology, Swedish Museum of Natural History, Box 50007, 10405 Stockholm, Sweden
| | - Anne Chenuil
- Aix-Marseille Université, Institut méditerranéen de biodiversité et d'écologie marine et continentale (IMBE), CNRS - IRD - UAPV, station marine d'Endoume, chemin de la Batterie-des-Lions, 13007 Marseille, France
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6
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Naughton KM, O'Hara TD, Appleton B, Gardner MG. Sympatric cryptic species in the crinoid genus Cenolia (Echinodermata: Crinoidea: Comasteridae) delineated by sequence and microsatellite markers. Mol Phylogenet Evol 2014; 78:160-71. [PMID: 24862222 DOI: 10.1016/j.ympev.2014.05.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 04/29/2014] [Accepted: 05/05/2014] [Indexed: 11/15/2022]
Abstract
The marine species of the southern coast of Australia have not been well studied with regard to molecular connectivity. Cryptic species are expected to be prevalent on this coastline. Here, we investigate the crinoid genus Cenolia (Echinodermata: Crinoidea: Comasteridae) using molecular methods to elucidate cryptic species and phylogenetic relationships. The genus Cenolia dominates the southern Australian crinoid fauna in shallow waters. Few studies have examined crinoids for cryptic species at a molecular level and these have been predominantly based on mitochondrial data. We employ the nuclear markers 28S rRNA and ITS-2 in addition to the mitochondrial COI. Six divergent mitochondrial clades were identified. Gene flow between confirmed clades was subsequently examined by the use of six novel microsatellite markers, showing that sympatric taxa with low mtDNA divergences (1.7% K2P) were not interbreeding in the wild. The type specimens of Cenolia benhami and C. spanoschistum were examined, as well as all six divergent clades. Morphological characters dividing taxa were refined. Due to comb pinnule morphology, the New Zealand species benhami was determined to belong to the genus Oxycomanthus (nov. comb.). Three new species of Cenolia (including the Australian "benhami") require description.
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Affiliation(s)
- K M Naughton
- Sciences, Museum Victoria, GPO Box 666, Melbourne, Victoria 3000, Australia; Department of Genetics, Faculty of Science, University of Melbourne, Parkville, Victoria 3010, Australia.
| | - T D O'Hara
- Sciences, Museum Victoria, GPO Box 666, Melbourne, Victoria 3000, Australia
| | - B Appleton
- Department of Genetics, Faculty of Science, University of Melbourne, Parkville, Victoria 3010, Australia
| | - M G Gardner
- School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide 5001, South Australia, Australia; Evolutionary Biology Unit, South Australian Museum, North Terrace, Adelaide 5000, South Australia, Australia
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7
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Bribiesca-Contreras G, Solís-Marín FA, Laguarda-Figueras A, Zaldívar-Riverón A. Identification of echinoderms (Echinodermata) from an anchialine cave in Cozumel Island, Mexico, using DNA barcodes. Mol Ecol Resour 2013; 13:1137-45. [PMID: 23551841 DOI: 10.1111/1755-0998.12098] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 02/19/2013] [Accepted: 02/26/2013] [Indexed: 11/29/2022]
Abstract
The echinoderm species richness of the Aerolito de Paraiso anchialine cave, on Cozumel Island, in the Mexican Caribbean, is assessed on the basis of morphological and DNA barcoding data. We included specimens from this cave system and from different open sea areas, and employed two different approaches for species delineation based on DNA barcoding data: a 2% cox1 divergence and the general mixed Yule-coalescent (GMYC) approaches. We subsequently compared the results derived from these approaches with our morphospecies discrimination. A total of 188 cox1 sequences belonging to specimens of four echinoderm classes were examined. The 2% cox1 divergence and GMYC approaches recovered 78 and 70 putative species, respectively, 24 and 22 of which corresponded to specimens from the anchialine system. Of 26 echinoderm species identified in the cave system, seven appear to be endemic to it. Among these are Copidaster carvenicola Solís-Marín & Laguarda-Figueras, 2010, two morphologically distinctive, undescribed species belonging to Asterinides and Ophionereis and four probably cryptic undescribed species originally assigned to Amphipholis squamata (Delle Chiaje, 1839), Astropecten duplicatus Gray, 1840, Copidaster lymani (AH Clark, 1948) and Ophiothrix angulata (Say, 1825). Further research and protection of this particularly fragile ecosystem becomes urgent because construction of tourism developments is planned nearby.
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Barbosa SS, Klanten SO, Puritz JB, Toonen RJ, Byrne M. Very fine-scale population genetic structure of sympatric asterinid sea stars with benthic and pelagic larvae: influence of mating system and dispersal potential. Biol J Linn Soc Lond 2013. [DOI: 10.1111/bij.12006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sergio S. Barbosa
- School of Medical Science; University of Sydney; Sydney; NSW; 2006; Australia
| | - Selma O. Klanten
- School of Medical Science; University of Sydney; Sydney; NSW; 2006; Australia
| | - Jonathan B. Puritz
- Hawaii Institute of Marine Biology; University of Hawai'i at Mānoa; Kaneohe; HI; 96744; USA
| | - Robert J. Toonen
- Hawaii Institute of Marine Biology; University of Hawai'i at Mānoa; Kaneohe; HI; 96744; USA
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9
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Genetic differentiation of the African dwarf crocodile Osteolaemus tetraspis Cope, 1861 (Crocodylia: Crocodylidae) and consequences for European zoos. ORG DIVERS EVOL 2012. [DOI: 10.1007/s13127-012-0107-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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10
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HEMERY LG, ELÉAUME M, ROUSSEL V, AMÉZIANE N, GALLUT C, STEINKE D, CRUAUD C, COULOUX A, WILSON NG. Comprehensive sampling reveals circumpolarity and sympatry in seven mitochondrial lineages of the Southern Ocean crinoid speciesPromachocrinus kerguelensis(Echinodermata). Mol Ecol 2012; 21:2502-18. [DOI: 10.1111/j.1365-294x.2012.05512.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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11
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Janosik AM, Halanych KM. Unrecognized Antarctic biodiversity: a case study of the genus Odontaster (Odontasteridae; Asteroidea). Integr Comp Biol 2010; 50:981-92. [PMID: 21558254 DOI: 10.1093/icb/icq119] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Antarctica has a complex and multifaceted geologic and oceanographic history that has influenced and shaped patterns of marine invertebrate diversity. This evolutionary history consists of major events on a wide range of time scales such as the formation of the Antarctic Polar Front (25-41 million years ago) to repeated glacial cycles during the past million years. These factors variably influenced genetic connectivity of fauna to produce a highly unique, but incredibly diverse marine community. Use of molecular phylogeographic methods is creating the need to revise our understanding of Antarctic patterns of biodiversity. In particular, almost every phylogeographic study carried out to date, suggests that the biodiversity of Antarctic marine shelf fauna is considerably underestimated. In discovering this diversity, some lineages (i.e., cryptic lineages) show no diagnostic morphological differences whereas others (i.e., unrecognized species) show differences that were unknown to science. The sea star genus Odontaster is among the best-studied of Antarctic invertebrate groups. Nonetheless, two unrecognized lineages were recently discovered along the Antarctic Peninsula, which is one of the best-studied regions in Antarctica. Herein, we elucidate the molecular and morphological uniqueness of these species and name them O. roseus and O. pearsei. The latter is in honor of John Pearse, an Antarctic biologist, as well as past President and long-time member of the Society of Integrative and Comparative Biology.
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Affiliation(s)
- Alexis M Janosik
- Department of Biological Sciences, Auburn University, 101 Rouse Life Sciences Building, Auburn, AL 36849, USA.
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Byrne M, Rowe F, Uthicke S. Molecular taxonomy, phylogeny and evolution in the family Stichopodidae (Aspidochirotida: Holothuroidea) based on COI and 16S mitochondrial DNA. Mol Phylogenet Evol 2010; 56:1068-81. [PMID: 20399872 DOI: 10.1016/j.ympev.2010.04.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Revised: 04/06/2010] [Accepted: 04/09/2010] [Indexed: 11/30/2022]
Abstract
The Stichopodidae comprise a diverse assemblage of holothuroids most of which occur in the Indo-Pacific. Phylogenetic analyses of mitochondrial gene (COI, 16S rRNA) sequence for 111 individuals (7 genera, 17 species) clarified taxonomic uncertainties, species relationships, biogeography and evolution of the family. A monophyly of the genus Stichopus was supported with the exception of Stichopus ellipes. Molecular analyses confirmed genus level taxonomy based on morphology. Most specimens harvested as S. horrens fell in the S. monotuberculatus clade, a morphologically variable assemblage with others from the S. naso clade. Taxonomic clarification of species fished as S. horrens will assist conservation measures. Evolutionary rates based on comparison of sequence from trans-ithmian Isostichopus species estimated that Stichopus and Isostichopus diverged ca. 5.5-10.7Ma (Miocene). More recent splits were estimated to be younger than 1Ma.
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Affiliation(s)
- Maria Byrne
- Schools of Medical and Biological Sciences, F13, University of Sydney, NSW 2006, Australia.
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13
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Xavier R, Santos AM, Lima FP, Branco M. Invasion or invisibility: using genetic and distributional data to investigate the alien or indigenous status of the Atlantic populations of the peracarid isopod, Stenosoma nadejda (Rezig 1989). Mol Ecol 2009; 18:3283-90. [PMID: 19555413 DOI: 10.1111/j.1365-294x.2009.04260.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The peracarid isopod, Stenosoma nadejda (Rezig 1989), until recently considered to be endemic of the Mediterranean region, was first reported in the Atlantic coast of southern Spain in 2001, and in 2006 abundant populations were discovered throughout the southwestern Portuguese coast. This fast expansion was intriguing because, as a direct brooder, this species has limited mechanisms for dispersal, such as rafting on seaweeds. Did S. nadejda recently extend its range into the Atlantic or was it overlooked in the past? We examined the patterns of genetic diversity and population differentiation accordingly by sequencing the cytochrome c oxidase subunit I mitochondrial gene from 75 individuals collected in five locations in Atlantic Iberia and one in the Mediterranean. Our results indicate that the newly discovered Atlantic populations of S. nadejda appear to be old and have long persisted on Atlantic shores rather than being a recent introduction. High levels of genetic diversity and geographic structure were uncovered in what was initially suspected to be an 'invasive' species. Recent changes in population dynamics may have made S. nadejda more conspicuous in the Atlantic shores, or a more comprehensive survey led to the recognition of this species where it was not expected.
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Affiliation(s)
- R Xavier
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, Vairão, Portugal.
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WILSON NERIDAG, SCHRÖDL M, HALANYCH KENNETHM. Ocean barriers and glaciation: evidence for explosive radiation of mitochondrial lineages in the Antarctic sea slugDoris kerguelenensis(Mollusca, Nudibranchia). Mol Ecol 2009; 18:965-984. [DOI: 10.1111/j.1365-294x.2008.04071.x] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Naughton KM, O'Hara TD. A new brooding species of the biscuit star Tosia (Echinodermata:Asteroidea:Goniasteridae), distinguished by molecular, morphological and larval characters. INVERTEBR SYST 2009. [DOI: 10.1071/is08021] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The biscuit star Tosia australis Gray, 1840 is a well known component of the shallow rocky reef fauna of south-eastern Australia. The putative T. australis species complex was subjected to reproductive, morphometric and molecular analyses. Molecular analyses of the data from three markers (mitochondrial COI and 16S rRNA and the nuclear non-coding region ITS2) confirmed the presence of a cryptic species, the morphology of which does not agree with any of the existing nominal species. Two separate reproductive modes were observed within the complex and documented via scanning electron microscopy. T. neossia, sp. nov., described herein from south-eastern Australia, is shown to release gametes from gonopores on the actinal surface. Embryos develop first into non-feeding, non-swimming brachiolaria, and then into tripod brachiolaria before metamorphosis. No surface cilia are present at any point throughout development of T. neossia. T. australis sensu stricto is shown to release gametes from the abactinal surface. Embryos develop into non-feeding, swimming brachiolaria before metamorphosis. Whereas T. australis var. astrologorum is confirmed as synonymous with T. australis, the status of the putative Western Australian taxon T. nobilis remains unresolved.
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Keever CC, Sunday J, Wood C, Byrne M, Hart MW. Discovery and cross-amplification of microsatellite polymorphisms in asterinid sea stars. THE BIOLOGICAL BULLETIN 2008; 215:164-172. [PMID: 18840777 DOI: 10.2307/25470697] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Variation in tandem repeats of two- to six-base nucleotide motifs (microsatellites) can be used to obtain inexpensive and highly informative multi-locus data on population genetics.We developed and tested a large set of cross-amplifiable sea star (Asterinidae) microsatellite markers from a mixed pool of genomic DNA from eight species. We describe cloned sequences, primers, and PCR conditions, and characterize population-level variation for some species and markers. A few clones containing microsatellites showed considerable similarity to sequences (including genes of known function) in other sea stars and in sea urchins (from the Strongylocentrotus purpuratus complete genome). The pooled genomic DNA method was an efficient way to sample microsatellites from many species: we cloned 2-10 microsatellites from each of eight species, and most could be cross-amplified in 1-7 other species. At 12 loci in two species, we found 1-10 alleles per microsatellite, with a broad range of inbreeding coefficients. Measures of polymorphism were negatively correlated with the extent of cross-amplification.
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Affiliation(s)
- Carson C Keever
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
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17
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Hunter RL, Halanych KM. Evaluating connectivity in the brooding brittle star Astrotoma agassizii across the drake passage in the Southern Ocean. ACTA ACUST UNITED AC 2008; 99:137-48. [PMID: 18245798 DOI: 10.1093/jhered/esm119] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Studies examining population structure and genetic diversity of benthic marine invertebrates in the Southern Ocean have emerged in recent years. However, many taxonomic groups remain largely unstudied, echinoderms being one conspicuous example. The brittle star Astrotoma agassizii is distributed widely throughout Antarctica and southern South America. This species is a brooding echinoderm and therefore may have limited dispersal capacity. In order to determine the effect of hypothesized isolating barriers in the Southern Ocean, such as depth, geographic distance, and the polar front, 2 mitochondrial DNA markers were used to compare populations from the South American and Antarctic continental shelves. Astrotoma agassizii was shown to be genetically discontinuous across the polar front. In fact, populations previously assumed to be panmictic instead represent 3 separate lineages that lack morphological distinction. However, within lineages, genetic continuity was displayed across a large geographic range (>500 km). Therefore, despite lacking a pelagic larval stage, A. agassizii can disperse across substantial geographic distance within continental shelf regions. These results indicate that geographic distance alone may not be a barrier to dispersal, but rather the combined effects of distance, depth, and the polar front act to prevent gene flow between A. agassizii populations in the Southern Ocean.
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Affiliation(s)
- Rebecca L Hunter
- Department of Biological Sciences, Auburn University, 101 Rouse Life Sciences Building, Auburn, AL 36849, USA.
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18
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Abstract
The generality of operational species definitions is limited by problematic definitions of between-species divergence. A recent phylogenetic species concept based on a simple objective measure of statistically significant genetic differentiation uses between-species application of statistical parsimony networks that are typically used for population genetic analysis within species. Here we review recent phylogeographic studies and reanalyse several mtDNA barcoding studies using this method. We found that (i) alignments of DNA sequences typically fall apart into a separate subnetwork for each Linnean species (but with a higher rate of true positives for mtDNA data) and (ii) DNA sequences from single species typically stick together in a single haplotype network. Departures from these patterns are usually consistent with hybridization or cryptic species diversity.
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Affiliation(s)
- Michael W Hart
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, Canada.
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