| 1. |
- Achurra, A., et al.
(författare)
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DNA barcoding and species delimitation: the Stylodrilus heringianus case (Annelida : Clitellata : Lumbriculidae)
- 2013
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Ingår i: Invertebrate Systematics. - 1445-5226. ; 27:1, s. 118-128
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Tidskriftsartikel (refereegranskat)abstract
- Individuals of the aquatic oligochaete species Stylodrilus heringianus Claparède, 1862 were collected across a part of this species’ distribution range in Sweden, Estonia, Great Britain and Spain to test whether they represent a single metapopulation or several separately evolving lineages. Using sequences of the barcoding gene cytochrome c oxidase subunit I (COI) and two nuclear genes (internal transcribed spacer region and histone 3), three different approaches were conducted: pairwise distance-method, Bayesian inference and network analysis. Both the COI phylogeny and network analyses were concordant in recovering six haplotype clusters, which showed a maximum genetic distance of 7.7% (K2P) among each other. Nevertheless, nuclear genes failed to confirm any lineage separation, and we conclude that the sampled specimens all belong to the same species. A phylogeographic history with allopatric divergence and secondary contact is suggested to explain this intraspecific pattern of mitochondrial divergence and nuclear non-divergence. The study shows that a mitochondrial single-locus approach can be problematic for the accurate delimitation of species, and we emphasise the need for nuclear genes as supplementary markers, when taxonomic resolution is assessed with COI barcodes.
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| 2. |
- Achurra, A., et al.
(författare)
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Pseudo-cryptic speciation in the subterranean medium: A new species of Stylodrilus Claparede, 1862, with a revision of the status of Bichaeta Bretscher, 1900 (Annelida, Clitellata, Lumbriculidae)
- 2015
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Ingår i: Zoologischer Anzeiger. - : Elsevier BV. - 0044-5231. ; 257, s. 71-86
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Tidskriftsartikel (refereegranskat)abstract
- The subterranean aquatic medium is known to harbor a large diversity of cryptic species. We describe a new aquatic clitellate, Stylodrilus mariae n. sp., from groundwaters in the Cantabrian region, northern Spain, using integrative taxonomy (morphological and molecular data). The new species shows inconspicuous morphological differences with Stylodrilus parvus s. lat. The tree topologies based on sequences of the barcoding gene Cytochrome Oxidase I (COI) and two nuclear markers i.e., internal transcribed spacer (ITS) region and histone 3 (H3) were concordant and revealed that S. parvus s. lat. and the new species are genetically well-differentiated. They are non-sister lineages, showing a maximum genetic (uncorrected p) distance of 20% for COI. Constrained phenotypic evolution is apparent in the clade within which S. mariae n. sp. and S. parvus are placed; this can explain the decoupling of morphological and molecular evolution in these two species although we cannot completely discard convergent evolution. Based on molecular data, the former Bichaeta sanguinea clusters within the genus Stylodrilus, and since this is concordant with the morphology, Stylodrilus sanguineus (Bretscher, 1900) n. comb, is proposed. (C) 2015 Elsevier GmbH. All rights reserved.
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| 5. |
- Anderson, F. E., et al.
(författare)
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Phylogenomic analyses of Crassiclitellata support major Northern and Southern Hemisphere clades and a Pangaean origin for earthworms
- 2017
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Ingår i: Bmc Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 17
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Tidskriftsartikel (refereegranskat)abstract
- Background: Earthworms (Crassiclitellata) are a diverse group of annelids of substantial ecological and economic importance. Earthworms are primarily terrestrial infaunal animals, and as such are probably rather poor natural dispersers. Therefore, the near global distribution of earthworms reflects an old and likely complex evolutionary history. Despite a long-standing interest in Crassiclitellata, relationships among and within major clades remain unresolved. Methods: In this study, we evaluate crassiclitellate phylogenetic relationships using 38 new transcriptomes in combination with publicly available transcriptome data. Our data include representatives of nearly all extant earthworm families and a representative of Moniligastridae, another terrestrial annelid group thought to be closely related to Crassiclitellata. We use a series of differentially filtered data matrices and analyses to examine the effects of data partitioning, missing data, compositional and branch-length heterogeneity, and outgroup inclusion. Results and discussion: We recover a consistent, strongly supported ingroup topology irrespective of differences in methodology. The topology supports two major earthworm clades, each of which consists of a Northern Hemisphere subclade and a Southern Hemisphere subclade. Divergence time analysis results are concordant with the hypothesis that these north-south splits are the result of the breakup of the supercontinent Pangaea. Conclusions: These results support several recently proposed revisions to the classical understanding of earthworm phylogeny, reveal two major clades that seem to reflect Pangaean distributions, and raise new questions about earthworm evolutionary relationships.
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| 6. |
- Appeltans, W., et al.
(författare)
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The Magnitude of Global Marine Species Diversity
- 2012
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Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 22:23, s. 2189-2202
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Tidskriftsartikel (refereegranskat)abstract
- Background: The question of how many marine species exist is important because it provides a metric for how much we do and do not know about life in the oceans. We have compiled the first register of the marine species of the world and used this baseline to estimate how many more species, partitioned among all major eukaryotic groups, may be discovered. Results: There are similar to 226,000 eukaryotic marine species described. More species were described in the past decade (similar to 20,000) than in any previous one. The number of authors describing new species has been increasing at a faster rate than the number of new species described in the past six decades. We report that there are similar to 170,000 synonyms, that 58,000-72,000 species are collected but not yet described, and that 482,000-741,000 more species have yet to be sampled. Molecular methods may add tens of thousands of cryptic species. Thus, there may be 0.7-1.0 million marine species. Past rates of description of new species indicate there may be 0.5 +/- 0.2 million marine species. On average 37% (median 31%) of species in over 100 recent field studies around the world might be new to science. Conclusions: Currently, between one-third and two-thirds of marine species may be undescribed, and previous estimates of there being well over one million marine species appear highly unlikely. More species than ever before are being described annually by an increasing number of authors. If the current trend continues, most species will be discovered this century.
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| 7. |
- Arslan, N., et al.
(författare)
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Aquatic Oligochaeta (Annelida) of Balıkdamı wetland (Turkey), with description of two new species of Phallodrilinae
- 2007
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Ingår i: Biologia. - : Springer Science and Business Media LLC. - 0006-3088 .- 1336-9563. ; 62:3, s. 323-334
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Tidskriftsartikel (refereegranskat)abstract
- The Balıkdamı Wetland, an impoundment of the upper course of the Sakarya River located near Sivrihisar (Eskişehir, Central Anatolia), is one of the most important bird conservation areas in Turkey. This area also encompasses the mouth of the torrential Göksu Stream, which is partly hyporheic. During this study (2001–2003), 1,471 specimens representing 34 taxa of aquatic Oligochaeta were collected from the Balıkdamı Wetland. All the species identified are new records for Balıkdamı. Two species, Coralliodrilus amissus sp. n. and Gianius anatolicus sp. n., are new to science, and five species, Stylodrilus parvus (Hrabě et Černosvitov, 1927), Chaetogaster diastrophus (Gruithuisen, 1828), Peipsidrilus libanus (Giani et al., 1982), Tubifex acuticularis Martinez-Ansemil et Giani, 1983, and Epirodrilus moubayedi Giani et Martinez-Ansemil, 1983, are new records for Turkey. Two other species, Peipsidrilus libanus and Tubifex acuticularis, are re-described. The oligochaete fauna of the wetland was dominated by widely distributed tubificid taxa. The lumbriculid Stylodrilus parvus was the most abundant species in the Göksu stream. The two new phallodriline species are remarkable since most representatives of this subfamily live in the marine environment. Due to the species richness and diversity of Oligochaeta, as well as of several other animal groups, the Balıkdamı wetland area deserves conservation.
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| 8. |
- Bergin, Claudia, et al.
(författare)
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Acquisition of a Novel Sulfur-Oxidizing Symbiont in the Gutless Marine Worm Inanidrilus exumae
- 2018
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Ingår i: Applied and Environmental Microbiology. - : AMER SOC MICROBIOLOGY. - 0099-2240 .- 1098-5336. ; 84:7
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Tidskriftsartikel (refereegranskat)abstract
- Gutless marine oligochaetes (Annelida, Clitellata) lack a digestive and excretory system, and live in an obligate association with multiple bacterial endosymbionts that supply them with nutrition. In this study, we discovered an unusual symbiont community in the gutless oligochaete Inanidrilus exumae that differs markedly from the microbiome of all other 22 examined host species. Comparative 16S rRNA sequence analysis and fluorescence in situ hybridization revealed that I.exumae harboured co-occurring gamma-, alpha- and deltaproteobacterial symbionts, while all other host species harbour gamma- and either alpha- or deltaproteobacterial symbionts. Surprisingly, the primary chemoautotrophic, sulfur-oxidizer, Ca. Thiosymbion, which occurs in all other gutless oligochaetes, does not appear to be present in I.exumae. Instead, I. exumae harboured a bacterial endosymbiont that resembled Ca. Thiosymbion morphologically and metabolically, but originated from a novel lineage within the Gammaproteobacteria. This endosymbiont, named Gamma 4 symbiont here, had a 16S rRNA sequence that differed by at least 7% from those of other free-living and symbiotic bacteria and by 10% from Ca. Thiosymbion. Sulfur globules in the Gamma 4 symbiont cells, as well as the presence of genes characteristic for autotrophy (cbbL) and sulfur oxidation (aprA), suggest that this symbiont is a chemoautotrophic sulfur oxidizer. Our results indicate that a novel lineage of free-living bacteria was able to establish a stable and specific association with I. exumae, and displace the Ca. Thiosymbion symbionts originally associated with these hosts.
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| 9. |
- Blazejak, A., et al.
(författare)
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Coexistence of bacterial sulfide oxidizers, sulfate reducers, and spirochetes in a gutless worm (Oligochaeta) from the Peru margin
- 2005
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Ingår i: Applied and Environmental Microbiology. - 0099-2240. ; 71:3, s. 1553-1561
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Tidskriftsartikel (refereegranskat)abstract
- Olavius crassitunicatus is a small symbiont-bearing worm that occurs at high abundance in oxygen-deficient sediments in the East Pacific Ocean. Using comparative 16S rRNA sequence analysis and fluorescence in situ hybridization, we examined the diversity and phylogeny of bacterial symbionts in two geographically distant O. crassitunicatus populations (separated by 385 km) on the Peru margin (water depth, similar to 300 m). Five distinct bacterial phylotypes co-occurred in all specimens from both sites: two members of the gamma-Proteobacteria (Gamma 1 and 2 symbionts), two members of the delta-Proteobacteria (Delta I and 2 symbionts), and one spirochete. A sixth phylotype belonging to the delta-Proteobacteria (Delta 3 symbiont) was found in only one of the two host populations. Three of the O. crassitunicatus bacterial phylotypes are closely related to symbionts of other gutless oligochaete species; the Gamma 1 phylotype is closely related to sulfide-oxidizing symbionts of Olavius algarvensis, Olavius loisae, and Inanidrilus leukodermatus, the Delta 1 phylotype is closely related to sulfate-reducing symbionts of O . algarvensis, and the spirochete is closely related to spirochetal symbionts of O. loisae. In contrast, the Gamma 2 phylotype and the Delta 2 and 3 phylotypes belong to novel lineages that are not related to other bacterial symbionts. Such a phylogenetically diverse yet highly specific and stable association in which multiple bacterial phylotypes coexist within a single host has not been described previously for marine invertebrates.
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| 10. |
- Blazejak, A., et al.
(författare)
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Phylogeny of 16S rRNA, ribulose 1,5-bisphosphate carboxylase/oxygenasem and adenosine 5’-phosphosulfate reductase genes from gamma- and alphaproteobacterial symbionts in gutless marine worms (Oligochaeta) from Bermuda and the Bahamas.
- 2006
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Ingår i: Applied and Environmental Microbiology. - 0099-2240. ; 72:8, s. 5527-5536
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Tidskriftsartikel (refereegranskat)abstract
- Gutless oligochaetes are small marine worms that live in obligate associations with bacterial endosymbionts. While symbionts from several host species belonging to the genus Olavius have been described, little is known of the symbionts from the host genus Inanidrilus. In this study, the diversity of bacterial endosymbionts in Inanidrilus leukodermatus from Bermuda and Inanidrilus makropetalos from the Bahamas was investigated using comparative sequence analysis of the 16S rRNA gene and fluorescence in situ hybridization. As in all other gutless oligochaetes examined to date, I. leukodermatus and I. makropetalos harbor large, oval bacteria identified as Gamma 1 symbionts. The presence of genes coding for ribulose-1,5-bisphosphate carboxylase/oxygenase form I (cbbL) and adenosine 5'-phosphosulfate reductase (aprA) supports earlier studies indicating that these symbionts are chemoautotrophic sulfur oxidizers. Alphaproteobacteria, previously identified only in the gutless oligochaete Olavius loisae from the southwest Pacific Ocean, coexist with the Gamma 1 symbionts in both I. leukodermatus and I. makropetalos, with the former harboring four and the latter two alphaproteobacterial phylotypes. The presence of these symbionts in hosts from such geographically distant oceans as the Atlantic and Pacific suggests that symbioses with alphaproteobacterial symbionts may be widespread in gutless oligochaetes. The high phylogenetic diversity of bacterial endosymbionts in two species of the genus Inanidrilus, previously known only from members of the genus Olavius, shows that the stable coexistence of multiple symbionts is a common feature in gutless oligochaetes.
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