Torsten Hugo Struck

• Struck, T. H., Wey-Fabrizius, A. R., Golombek, A., Hering, L., Weigert, A., Bleidorn, C., Klebow, S., Iakovenko, N., Hausdorf, B., Petersen, M., Kück, P., Herlyn, H. & Hankeln, T. (2014). Platyzoan paraphyly based on phylogenomic data supports a non-coelomate ancestry of Spiralia. Molecular Biology and Evolution 31: 1833-1849.
• Weigert, A., Helm, C., Meyer, M., Nickel, B., Arendt, D., Hausdorf, B., Santos, S. R., Halanych, K. M., Purschke, G., Bleidorn, C. & Struck, T. H. (2014). Illuminating the base of the annelid tree using transcriptomics. Molecular Biology and Evolution 31: 1391-1401.
• Struck, T. H. (2014). TreSpEx – Detection of misleading signal in phylogenetic reconstructions based on tree information. Evolutionary Bioinformatics 10: 51-67.
• Struck, T. H. (2013). The impact of paralogy on phylogenomic studies – a case study on annelid relationships. PLoS ONE 8: e62892.
• Thornhill, D. J., Struck, T. H., Ebbe, B., Lee, R. W., Mendoza, G. F., Levin, L. A. & Halanych, K. M. (2012). Adaptive Radiation in Extremophilic Dorvilleids: Diversification of a Single Colonizer or Multiple Independent Lineages? Ecology & Evolution 2: 1958–1970.
• Struck, T. H., Paul, C., Hill, N., Hösel, C., Kube, M., Lieb, B., Meyer, A., Tiedemann, R., Purschke, G. & Bleidorn, C. (2011). Phylogenomic analyses unravel annelid evolution. Nature 471: 95-98.
• Struck, T. H. & Fisse, F. (2008). Phylogenetic position of Nemertea derived from phylogenomic data. Molecular Biology and Evolution 25: 728–736.
• Struck, T. H. (2007). Data congruence, paedomorphosis and salamanders. Frontiers in Zoology 4: 22.
• Struck, T. H., Schult, N., Kusen, T., Hickman, E., Bleidorn, C., McHugh, D. & Halanych, K. M. (2007). Annelida phylogeny and the status of Sipuncula and Echiura. BMC Evolutionary Biology 7:57.

• Cerca De Oliveira, Josè; Meyer, Christian; Purschke, Günter & Struck, Torsten H (2020). Delimitation of cryptic species drastically reduces the geographical ranges of marine interstitial ghost-worms (Stygocapitella; Annelida, Sedentaria). Molecular Phylogenetics and Evolution.  ISSN 1055-7903.  143 . doi: https://doi.org/10.1016/j.ympev.2019.106663 Full text in Research Archive. Show summary

  The recognition of cryptic species concealed in traditionally established species may reveal new biogeographical patterns and alter the understanding of how biodiversity is geographically distributed. This is particularly relevant for marine ecosystems where the incidence of cryptic species is high and where species distribution data are often challenging to collect and interpret. Here, we studied specimens of the ‘cosmopolitan’ interstitial meiofaunal annelid Stygocapitella subterranea Knöllner, 1934 (Parergodrilidae, Orbiniida), obtaining data from four coastlines in the Northern hemisphere. Using phylogenetic tools and several species-delimitation methods (haplotype networks, GMYC, bPTP, maximum likelihood, posterior probability and morphology) we describe eight new Stygocapitella species. With one exception, all species are present along a single coastline, ultimately challenging the idea that Stygocapitella subterranea has a cosmopolitan distribution. We found evidence for several oceanic transitions having occurred in the past as well as a recent translocation, potentially due to human activity. No diagnostic characters were found, and qualitative and quantitative morphological data do not allow an unequivocal differentiation of the identified cryptic species. This suggests that (i) neither traditional diagnostic features nor quantitative morphology suffice to recognise species boundaries in cryptic species complexes, such as the Stygocapitella species complex; and that (ii) the recognition and description of cryptic species is of seminal importance for biodiversity assessments, biogeography and evolutionary biology.

• Cerca De Oliveira, Josè; Meyer, Christian; Purschke, Gunter & Struck, Torsten Hugo (2020). Delimitation of cryptic species drastically reduces the geographical ranges of marine interstitial ghost-worms (Stygocapitella; Annelida, Sedentaria). Molecular Phylogenetics and Evolution.  ISSN 1055-7903.  143:106663, s 1- 16 . doi: 10.1016/j.ympev.2019.106663
• Cerca De Oliveira, Josè; Meyer, Christian; Stateczny, Dave; Siemon, Dominik; Wegbrod, Jana; Purschke, Günter; Dimitrov, Dimitar & Struck, Torsten H (2020). Deceleration of morphological evolution in a cryptic species complex and its link to paleontological stasis. Evolution.  ISSN 0014-3820.  74(1), s 116- 131 . doi: doi:10.1111/evo.13884 Full text in Research Archive. Show summary

  Morphological stasis or the absence of morphological change is a well-known phenomenon in the paleontological record, yet it is poorly integrated with neontological evidence. Recent evidence suggests that cryptic species complexes may remain morphologically identical due to morphological stasis. Here, we describe a case of long-term stasis in the Stygocapitella cryptic species complex (Parergodrilidae, Orbiniida, Annelida). Using phylogenetic methods and morphological data, we find that rates of morphological evolution in Stygocapitella are significantly slower than in closely related taxa (Nerillidae, Orbiniidae). Assessment of quantitative and qualitative morphology revealed the presence of four morphotypes with only subtle differences, whereas molecular data supports 10 reproductively isolated clades. Notably, estimates for the time of Stygocapitella species divergence range from 275 million years to 18 million years, including one case of two morphologically similar species that have diverged about 140 million years ago. These findings provide evidence for morphological deceleration and long-term morphological stasis in Stygocapitella, and that speciation is not necessarily accompanied by morphological changes. The deceleration of morphological divergence in Stygocapitella can be potentially linked to niche conservatism and tracking, coupled with the fluctuating dynamics of the interstitial environment, or genetic constraints due to progenetic evolution. Finally, we conclude that failing to integrate speciation without morphological evolution in paleontology may bias estimates of rates of speciation and morphological evolution.

• Elgetany, Asmaa Haris; Rensburg, Hendré van; Hektoen, Martin Mejdell; Matthee, Conrad; Budaeva, Nataliya; Simon, Carol A. & Struck, Torsten H (2020). Species delineation in the speciation grey zone—The case of Diopatra (Annelida, Onuphidae). Zoologica Scripta.  ISSN 0300-3256.  49(4), s 516- 534 . doi: 10.1111/zsc.12421 Show summary

  Taxonomy based on morphology can be difficult. The challenges arise from different sources such as poor original descriptions, new records based on inadequate knowledge, uncritical application of general assumptions or presence of complexes of cryptic species. One example of problematic taxonomy is the genus Diopatra Audouin & Milne Edwards, 1833 (Onuphidae, Annelida) and within it the two species Diopatra aciculata and D. neapolitana. The species exhibit great similarity between them casting doubts on their validity as separate species. Our study aims to investigate whether D. aciculata and D. neapolitana should be synonymized, using an integrative taxonomic approach. Therefore, we assessed 22 morphological characters of 70 specimens including one specimen, which might have been erroneously assigned to D. dentata. Additionally, sequence information of five different molecular markers (i.e., 16S rDNA, COI, 28S, ITS1 and ITS2) was gathered to delineate possible species boundaries between these two species. Our results show some evidence for delineating the two species, but they are not conclusive due to both presence of shared morphological characters and conflicting evidence in the molecular data. Accordingly, our results neither confirm nor disprove complete speciation and both species seem to be in the grey zone of speciation. In conclusion, considering taxonomic stability and slight support by morphological characters, we still regard each as two independent species.

• Pazoki, Samaneh; Rahimian, Hassan; Struck, Torsten H; Katouzian, Ahmad R. & Kupriyanova, Elena K. (2020). A new species of the Spirobranchus kraussii-complex (Annelida, Serpulidae)from the Persian Gulf and Gulf of Oman. Zootaxa.  ISSN 1175-5326.  4748(3), s 401- 430 . doi: https://doi.org/10.11646/zootaxa.4748.3.1 Show summary

  A recent study (Simon et al. 2019) confirmed that Spirobranchus kraussii is neither a widely distributed tropical species of Indo-Pacific origin nor a Lessepsian migrant to the Mediterranean, but a large complex of species, some of which might be indeed invasive. Thus, a common intertidal gregarious serpulid, previously attributed to S. kraussii in the Persian Gulf and Gulf of Oman, is described herein as Spirobranchus sinuspersicus sp. nov., using a combination of morphological and molecular data. The new species differs from S. kraussii by smaller size, fewer abdominal chaetigers, arrangement of abdominal chaetae and shape of opercular endplate talon. Results of phylogenetic analyses of a dataset combining 18S nucleotide and Cyt-b amino-acid sequences of S. sinuspersicus sp. nov. and Spirobranchus spp. available from GenBank supported monophyly of S. kraussii complex (including S. cariniferus) nested within Spirobranchus and thus, provided molecular support for synonymy of Pomatoleios with Spirobranchus proposed based on morphological criteria. The new species forms a well-supported clade with (S. kraussii (sp. 2 Hawaii + sp. 3 Australia)) clade, which in turn forms a clade with Spirobranchus sp.1 from temperate Japan, while S. cariniferus from New Zealand forms a basal grade. Evidence of substitution saturation of Cyt-b nucleotide sequences suggests that using translated amino-acid sequences to exclude noninformative substitutions should provide a better phylogenetic resolution for the genus Spirobranchus. Further studies are required to determine the invasive status of S. sinuspersicus sp. nov. as well as taxonomic and invasive status of S. cf. kraussii populations from the Mediterranean Sea, Suez Bay, Pakistan, India, Sri Lanka, Philippines, Singapore, and Panama.

• Struck, Torsten H (2019). Phylogeny, In Günter Purschke; Markus Böggemann & Wilfried Westheide (ed.),  Handbook of Zoology: Annelida.  Walter de Gruyter.  ISBN 978-3-11-029146-9.  2.  s 37 - 68
• Struck, Torsten H & Cerca De Oliveira, Josè (2019). Cryptic Species and Their Evolutionary Significance. Encyclopedia of Life Sciences.  ISSN 1476-9506. . doi: DOI: 10.1002/9780470015902.a0028292 Full text in Research Archive.
• Cerca De Oliveira, Josè; Purschke, Günter & Struck, Torsten H (2018). Marine connectivity dynamics: clarifying cosmopolitan distributions of marine interstitial invertebrates and the meiofauna paradox. Marine Biology.  ISSN 0025-3162.  165(8) . doi: 10.1007/s00227-018-3383-2 Full text in Research Archive.
• Elgetany, Asmaa H.; El-Ghobashy, Ahmed E.; Ghoneim, Ahmad & Struck, Torsten H (2018). Description of a new species of the genus Marphysa (Eunicidae), Marphysa aegypti sp.n., based on molecular and morphological evidence. Invertebrate Zoology.  ISSN 1812-9250.  15(1), s 71- 84 . doi: 10.15298/invertzool.15.1.05 Full text in Research Archive.
• Helm, Conrad; Beckers, Patrick; Bartolomaeus, Thomas; Drukewitz, Stephan H.; Kourtesis, Ioannis; Weigert, Anne; Purschke, Günter; Worsaae, Katrine; Struck, Torsten H & Bleidorn, Christoph (2018). Convergent evolution of the ladder-like ventral nerve cord in Annelida. Frontiers in Zoology.  ISSN 1742-9994.  15(1) . doi: 10.1186/s12983-018-0280-y Full text in Research Archive.
• Ramey-Balci, Patricia; Fiege, Dieter & Struck, Torsten H (2018). Molecular phylogeny, morphology, and distribution of Polygordius (Polychaeta: Polygordiidae) in the Atlantic and Mediterranean. Molecular Phylogenetics and Evolution.  ISSN 1055-7903.  127, s 919- 930 . doi: 10.1016/j.ympev.2018.06.039 Full text in Research Archive.
• Struck, Torsten H (2017). Phylogeny of Annelida, In Ponnampalam Gopalakrishnakone & Anita Malhotra (ed.),  Evolution of Venomous Animals and Their Toxins.  Springer Science+Business Media B.V..  ISBN 978-94-007-6457-6.  Chapter 18.  s 399 - 413
• Struck, Torsten H (2017). Spiralia/Lophotrochozoa, In Michel Laurin (ed.),  Evolution of Phylogenetic Tree of Life.  Eolss Publishing CO. Ltd..  ISBN 9781780215242.  Chapter.
• Struck, Torsten H; Feder, Jeffrey L.; Bendiksby, Mika; Birkeland, Siri; Cerca De Oliveira, Josè; Gusarov, Vladimir; Kistenich, Sonja; Larsson, Karl-Henrik; Liow, Lee Hsiang; Nowak, Michael; Stedje, Brita; Bachmann, Lutz & Dimitrov, Dimitar (2017). Finding Evolutionary Processes Hidden in Cryptic Species. Trends in Ecology & Evolution.  ISSN 0169-5347.  33(3), s 153- 163 . doi: 10.1016/j.tree.2017.11.007 Full text in Research Archive. Show summary

  Cryptic species could represent a substantial fraction of biodiversity. However, inconsistent definitions and taxonomic treatment of cryptic species prevent informed estimates of their contribution to biodiversity and impede our understanding of their evolutionary and ecological significance. We propose a conceptual framework that recognizes cryptic species based on their low levels of phenotypic (morphological) disparity relative to their degree of genetic differentiation and divergence times as compared to non-cryptic species. We discuss how application of a more rigorous definition of cryptic species in taxonomic practice will lead to more accurate estimates of their prevalence in nature, better understanding of their distribution patterns on the tree of life, and increased abilities to resolve the processes underlying their evolution.

• Struck, Torsten H; Koczula, Jens; Stateczny, Dave; Meyer, Christian & Purschke, Günter (2017). Two new species in the annelid genus Stygocapitella (Orbiniida, Parergodrilidae) with comments on their biogeography. Zootaxa.  ISSN 1175-5326.  4286(3), s 301- 332 . doi: 10.11646/zootaxa.4286.3.1
• Aguado, Maria Teresa; Richter, Sandy; Sontowski, Rebekka; Golombek, Anja; Struck, Torsten Hugo & Bleidorn, Christoph (2016). Syllidae mitochondrial gene order is unusually variable for Annelida. Gene.  ISSN 0378-1119.  594(1), s 89- 96 . doi: 10.1016/j.gene.2016.08.050 Full text in Research Archive. Show summary

  Complete mitochondrial genomes of five syllids (Streptosyllis sp., Eusyllis blomstrandi, Myrianida brachycephala, Typosyllis antoni and Typosyllis sp.) have been obtained using Illumina sequencing. Together with two previous studied taxa (Ramisyllis multicaudata and Trypanobia cryptica), the analysed sequences represent most of the main lineages within the family Syllidae (Anoplosyllinae, Eusyllinae, Autolytinae and Syllinae). The genomic features, gene order and phylogenetic relationships are examined. Unusual for annelids, syllid mitochondrial genomes are highly variable in their gene order. Considering genomic features, such as length, skewness, gene content, and codon bias, most similar to the rest of annelids are the genomes of E. blomstrandi and M. brachycephala, while Streptosyllis sp. and the analysed sylline taxa (R. multicaudata, T. cryptica, T. antoni and Typosyllis sp.) are the most dissimilar. Two methionine tRNA's (trnM) have been found in T. antoni and Typosyllis sp. The mt genomes of these latter taxa are the longest with numerous non-coding regions. The 13 protein coding genes, as well as the rRNA's are used to perform phylogenetic analyses that recovered the relationships within the family explored before by previous authors. The gene order in Syllidae shows very different patterns. E. blomstrandi and M. prolifera show a similar pattern to the one found in Pleistoannelida; however this might have changed at least twice within Syllidae: in Streptosyllis sp. and within Syllinae. All analysed Syllinae show different gene orders, thereby illustrating more variability as all other pleistoannelids analysed so far. The information provided herein allows a more accurate reconstruction of the possible evolutionary scenarios in Syllidae.

• Kocot, Kevin M.; Struck, Torsten H; Merkel, Julia; Waits, Damien S.; Todt, Christiane; Bannock, Pamela M.; Weese, David A.; Cannon, Johanna T.; Moroz, Leonid L.; Lieb, Bernhard & Halanych, Kenneth M. (2016). Phylogenomics of Lophotrochozoa with consideration of systematic error. Systematic Biology.  ISSN 1063-5157.  66(2), s 256- 282 . doi: 10.1093/sysbio/syw079 Full text in Research Archive. Show summary

  Abstract.—Phylogenomic studies have improved understanding of deep metazoan phylogeny and show promise for resolving incongruences among analyses based on limited numbers of loci. One region of the animal tree that has been especially difficult to resolve, even with phylogenomic approaches, is relationships within Lophotrochozoa (the animal clade that includes molluscs, annelids, and flatworms among others). Lack of resolution in phylogenomic analyses could be due to insufficient phylogenetic signal, limitations in taxon and/or gene sampling, or systematic error. Here, we investigated why lophotrochozoan phylogeny has been such a difficult question to answer by identifying and reducing sources of systematic error. We supplemented existing data with 32 new transcriptomes spanning the diversity of Lophotrochozoa and constructed a new set of Lophotrochozoa-specific core orthologs. Of these, 638 orthologous groups (OGs) passed strict screening for paralogy using a tree-based approach. In order to reduce possible sources of systematic error, we calculated branch-length heterogeneity, evolutionary rate, percent missing data, compositional bias, and saturation for each OG and analyzed increasingly stricter subsets of only the most stringent (best) OGs for these five variables. Principal component analysis of the values for each factor examined for each OG revealed that compositional heterogeneity and average patristic distance contributed most to the variance observed along the first principal component while branch-length heterogeneity and, to a lesser extent, saturation contributed most to the variance observed along the second. Missing data did not strongly contribute to either. Additional sensitivity analyses examined effects of removing taxa with heterogeneous branch lengths, large amounts of missing data, and compositional heterogeneity. Although our analyses do not unambiguously resolve lophotrochozoan phylogeny, we advance the field by reducing the list of viable hypotheses. Moreover, our systematic approach for dissection of phylogenomic data can be applied to explore sources of incongruence and poor support in any phylogenomic data set.

• Sielaff, Malte; Schmidt, Hanno; Struck, Torsten Hugo; Rosenkranz, David; Mark Welch, David B.; Hankeln, Thomas & Herlyn, Holger (2016). Phylogeny of Syndermata (syn. Rotifera): Mitochondrial gene order verifies epizoic Seisonidea as sister to endoparasitic Acanthocephala within monophyletic Hemirotifera. Molecular Phylogenetics and Evolution.  ISSN 1055-7903.  96, s 79- 92 . doi: 10.1016/j.ympev.2015.11.017

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• Austin, Rita M; Struck, Torsten H & Bachmann, Lutz (2020). Blog post "Bringing museum specimens back into the light: Meet the new postdoctoral researcher molecularly exploring museum collections ".
• Cerca, Jose; Johnsen, Arild; Struck, Torsten H & Bachmann, Lutz (2020). Naturhistoriske samlinger i den molekylære æraen: En kostbar hobby eller en bærebjelke for moderne forskning?. Naturen.  ISSN 0028-0887.  (3), s 110- 116 . doi: https://doi.org/10.18261/issn.1504-3118-2020-03-07
• Fleming, James F; Struck, Torsten H & Bachmann, Lutz (2020). Blog post "Coming from Japan all the way to Norway".
• Gusarov, Vladimir; Struck, Torsten H & Bachmann, Lutz (2020). Blog post "Beetles on the Falkland islands".
• Gusarov, Vladimir; Struck, Torsten H & Bachmann, Lutz (2020). Blog post "Summer project at rocky shores".
• Gusarov, Vladimir; Struck, Torsten H & Bachmann, Lutz (2020). Blog post "Training in African Insect Biodiversity".
• Haugen, Marianne Nilsen; Struck, Torsten H & Bachmann, Lutz (2020). Blog post "Beetles, sheep and the Faroes".
• Haugen, Marianne Nilsen; Struck, Torsten H & Bachmann, Lutz (2020). Blog post "The intertidal beetle genus Aegialites".
• Haugen, Marianne Nilsen; Valero-Gracia, Alberto; Austin, Rita M; Struck, Torsten H & Bachmann, Lutz (2020). Blog post "Combining group fun with genomic research".
• Haugen, Marianne Nilsen; Valero-Gracia, Alberto; Cerca, José; Austin, Rita M; Fleming, James F; Gusarov, Vladimir; Struck, Torsten H & Bachmann, Lutz (2020). Blog post "International Happy Seasons".
• Struck, Torsten H (2020). Cryptic species and stasis - the interstitial annelid genus Stygocapitella as a case study.
• Struck, Torsten H (2020). The evolutionary significance of a cryptic species, a supposedly purely taxonomic problem.
• Struck, Torsten H & Bachmann, Lutz (2020). Blog post "A tale of stone and ice".
• Struck, Torsten H & Bachmann, Lutz (2020). Blog post "Assessing biodiversity in the marine algae belt".
• Struck, Torsten H & Bachmann, Lutz (2020). Blog post "Did the vikings bring beetles along to Iceland?".
• Struck, Torsten H & Bachmann, Lutz (2020). Blog post "From small body size to big data".
• Struck, Torsten H & Bachmann, Lutz (2020). Blog post "Huge and endangered".
• Struck, Torsten H & Bachmann, Lutz (2020). Blog post "Meiofauna occuring at public swimming beaches on Nesodden".
• Struck, Torsten H & Bachmann, Lutz (2020). Blog post "Natural history collections in the molecular era".
• Struck, Torsten H & Bachmann, Lutz (2020). Blog post "Never Cry Wolf".
• Struck, Torsten H & Bachmann, Lutz (2020). Blog post "Probing the mud".
• Struck, Torsten H & Bachmann, Lutz (2020). Blog post "Teaching in Covid times".
• Struck, Torsten H & Bachmann, Lutz (2020). Blog post "The first defense".
• Struck, Torsten H & Bachmann, Lutz (2020). Blog post "The first door of the calendar ".
• Struck, Torsten H & Bachmann, Lutz (2020). Blog post "The wrong food chain".
• Struck, Torsten H & Bachmann, Lutz (2020). Blog post "Where do all the sharks live".
• Valero-Gracia, Alberto; Struck, Torsten H & Bachmann, Lutz (2020). Blog post "A new PhD student in town".
• Struck, Torsten H; Feder, Jeffrey L.; Bendiksby, Mika; Birkeland, Siri; Cerca De Oliveira, Josè; Gusarov, Vladimir; Kistenich, Sonja; Larsson, Karl-Henrik; Liow, Lee Hsiang; Nowak, Michael; Stedje, Brita; Bachmann, Lutz & Dimitrov, Dimitar (2018). Cryptic Species – More Than Terminological Chaos: A Reply to Heethoff. Trends in Ecology & Evolution.  ISSN 0169-5347.  33(5), s 310- 312 . doi: 10.1016/j.tree.2018.02.008

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