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Mitochondrial sequence data expose the putative cosmopolitan polychaete Scoloplos armiger (Annelida, Orbiniidae) as a species complex.

ABSTRACT: BACKGROUND:Polychaetes assigned as Scoloplos armiger (Orbiniidae) show a cosmopolitan distribution and have been encountered in all zoogeographic regions. Sibling S. armiger-like species have been revealed by recent studies using RAPDs and AFLP genetic data. We sequenced an approximately 12 kb fragment of the Scoloplos cf. armiger mitochondrial genome and developed primers for variable regions including the 3' end of the cox3 gene, trnQ, and most of nad6. A phylogenetic analysis of this 528-nucleotide fragment was carried out for S. armiger-like individuals from the Eastern North Atlantic as well as Pacific regions. The aim of this study is to test the cosmopolitan status, as well as to clarify the systematics of this species complex in the Eastern North Atlantic, while using a few specimens from the Pacific Ocean for comparision. RESULTS:Phylogenetic analysis of the cox3-trnQ-nad6 data set recovered five different clades of Scoloplos cf. armiger. The fragment of the mitochondrial genome of Scoloplos cf. armiger is 12,042 bp long and contains 13 protein coding genes, 15 of the 22 expected tRNAs, and the large ribosomal subunit (rrnl). CONCLUSION:The sequenced cox3-trnQ-nad6 fragment proved to be very useful in phylogenetic analyses of Scoloplos cf. armiger. Due to its larger sampling scale this study goes beyond previous analyses which used RAPD and AFLP markers. The results of this study clearly supports that Scoloplos armiger represents a species complex and not a cosmopolitan species. We find at least two S. armiger-like species within the Pacific region and three different S. armiger-like species in the North Atlantic. Implications for the taxonomy and the impact on ecological studies are discussed.

SUBMITTER: Bleidorn C

PROVIDER: S-EPMC1550730 | biostudies-literature | 2006 Jun

REPOSITORIES: biostudies-literature

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Mitochondrial sequence data expose the putative cosmopolitan polychaete Scoloplos armiger (Annelida, Orbiniidae) as a species complex.

Bleidorn Christoph C Kruse Inken I Albrecht Sylvia S Bartolomaeus Thomas T

BMC evolutionary biology 20060615

<h4>Background</h4>Polychaetes assigned as Scoloplos armiger (Orbiniidae) show a cosmopolitan distribution and have been encountered in all zoogeographic regions. Sibling S. armiger-like species have been revealed by recent studies using RAPDs and AFLP genetic data. We sequenced an approximately 12 kb fragment of the Scoloplos cf. armiger mitochondrial genome and developed primers for variable regions including the 3' end of the cox3 gene, trnQ, and most of nad6. A phylogenetic analysis of this ...[more]

PMID: 16776822

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Project description:BackgroundTranscription factors that encode ANTP-class homeobox genes play crucial roles in determining the body plan organization and specification of different organs and tissues in bilaterian animals. The three-gene ParaHox family descends from an ancestral gene cluster that existed before the evolution of the Bilateria. All three ParaHox genes are reported from deuterostomes and lophotrochozoans, but not to date from any ecdysozoan taxa, and there is evidence that the ParaHox genes, like the related Hox genes, were ancestrally a single chromosomal cluster. However, unlike the Hox genes, there is as yet no strong evidence that the ParaHox genes are expressed in spatial and temporal order during embryogenesis.ResultsWe isolated fragments of the three Nereis virens ParaHox genes, then used these as probes for whole-mount in situ hybridization in larval and postlarval worms. In Nereis virens the ParaHox genes participate in antero-posterior patterning of ectodermal and endodermal regions of the digestive tract and are expressed in some cells in the segment ganglia. The expression of these genes occurs in larval development in accordance with the position of these cells along the main body axis and in postlarval development in accordance with the position of cells in ganglia along the antero-posterior axis of each segment. In none of these tissues does expression of the three ParaHox genes follow the rule of temporal collinearity.ConclusionIn Nereis virens the ParaHox genes are expressed during antero-posterior patterning of the digestive system (ectodermal foregut and hindgut, and endodermal midgut) of Nereis virens. These genes are also expressed during axial specification of ventral neuroectodermal cell domains, where the expression domains of each gene are re-iterated in each neuromere except for the first parapodial segment. These expression domains are probably predetermined and may be directed on the antero-posterior axis by the Hox genes, whose expression starts much earlier during embryogenesis. Our results support the hypothesis that the ParaHox genes are involved in antero-posterior patterning of the developing embryo, but they do not support the notion that these genes function only in the patterning of endodermal tissues.

Project description:Spiophanes bombyx (Claparède, 1870) from the Gulf of Naples, Tyrrhenian Sea, Italy, was the first described Spiophanes with fronto-lateral horns on the prostomium. It was also considered the only horned species occurring in European waters. Our sequence data of five gene fragments suggest the presence of two horned sibling Spiophanes species in northern Europe: S. cf. bombyx in the North and the Norwegian seas, and S. cf. convexus in Brittany, northern France, and Bay of Biscay, northern Spain. Spiophanes cf. bombyx worms are genetically close to a single examined specimen of S. bombyx from Venice Lagoon, Italy but their conspecificity should be verified by further study. Our sequence data show that horned Spiophanes from the North Pacific are genetically distant from horned European species, and that S. uschakowi Zachs, 1933, originally described from the Sea of Japan (East Sea) is a valid species. The data also suggest the presence of two horned sibling Spiophanes species in the North East Pacific: S. hakaiensis Radashevsky & Pankova, n. sp. distributed from Alaska south to about Point Conception, and S. norrisi Meißner & Blank, 2009, distributed from San Francisco Bay south to Baja California Sur, Mexico. Spiophanes from South America, morphologically similar to S. norrisi, are suggested to belong to a new species. Molecular data also suggest the presence of two sibling species among the worms from northern Europe identified by morphology as S. kroyeri Grube, 1860. Worms from the Barents Sea and northern part of the North Sea are tentatively referred to as S. cf. kroyeri; worms from the northern and central parts of the North Sea and from the Bay of Biscay, northern Spain, are tentatively referred to as S. cf. cirrata M. Sars in G.O. Sars, 1872. Sequence data also show that S. duplex from California is genetically different from morphologically similar worms from South America. The South American worms are referred to resurrected S. soederstroemi Hartman, 1953 which was originally described from off Rio Grande do Sul, Brazil, and then considered as a junior synonym of S. duplex. Analysis of divergence times of Spiophanes lineages suggested that the origin of the most recent common ancestor of horned Spiophanes with metameric nuchal organs was around 11.1 mya (95% HPD: 5.1-19.0 mya) and that the divergence of the North Atlantic and North Pacific lineages was around 7.9 mya (95% HPD: 4.1-13.3 mya). The North Atlantic lineage was estimated to have diverged 4.8 mya (95% HPD: 2.2-8.6 mya), resulting in the origin of S. cf. bombyx and S. cf. convexus. The North Pacific lineage was estimated to have diverged first by the isolation and speciation of S. norrisi 1.7 mya (95% HPD: 2.3-1.0 mya), and then by the isolation and speciation of S. uschakowi and S. hakaiensis n. sp. 1.3 mya (95% HPD: 2.0-0.7 mya). The estimates place the divergences soon after maximum glacial period in the North Pacific (2.4-3.0 mya).

Dataset Information

Mitochondrial sequence data expose the putative cosmopolitan polychaete Scoloplos armiger (Annelida, Orbiniidae) as a species complex.

Publications

Mitochondrial sequence data expose the putative cosmopolitan polychaete Scoloplos armiger (Annelida, Orbiniidae) as a species complex.

Similar Datasets

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