Phylogeny and systematics of Caudofoveata (Mollusca, Aplacophora)

Caudofoveata is by far the least known group of molluscs. The shell-less, wormshaped caudofoveate molluscs are characterized by a mantle covered in calcareous sclerites, giving them a distinctive, shiny appearance. Caudofoveata consists of 141 recognized species found from intertidal habitats to the deep-sea, where they live burrowing in sediments. Three families are recognized within Caudofoveata; Prochaetodermatidae SalviniPlawen, 1975, Chaetodermatidae Ihering, 1876, and Limifossoridae Salvini-Plawen, 1970. Evolutionary relationships of the group have been debated, yet studies investigating the phylogeny of the group have been lacking. In this thesis, the phylogenetic relationships within and among the families of Caudofoveata are investigated using molecular phylogenetics and analyses of whole mitochondrial genomes. Special emphasis was put on the fauna of the northern Atlantic Ocean, including the description of a new species, and a thorough investigation of one of the most common species in the area. In order to investigate relationships among and within families of Caudofoveata, phylogenetic analyses were performed using six sequenced fragments of selected mitochondrial and nuclear genes from 38 species representing all three recognized families of Caudofoveata with species from worldwide sampling locations. In resulting trees, contrary to traditional views, Prochaetodermatidae is sister to a clade containing the other two currently recognized families, Chaetodermatidae and Limifossoridae. The monophyly of Prochaetodermatidae is highly supported, but Limifossoridae and Chaetodermatidae are not recovered as monophyletic. Most of the caudofoveate genera are also not recovered as monophyletic in our analyses. Thus, results from our molecular data suggest that current classification of the group is in need of revision and indicate different evolutionary scenarios than previous hypotheses based on morphology. Within the family Chaetodermatidae, Chaetoderma nitidulum Lovén, 1844 is a common species of caudofoveate with a wide distribution range in the North Atlantic. It was the first species of aplacophoran mollusc to be described, but its species identity has been debated. Here, the molecular and morphological diversity of specimens of C. nitidulum from a large geographical area and size range was investigated. Analyses of molecular data revealed two distinct genetic lineages in the eastern Atlantic and one clade sister to these in the western Atlantic Ocean. Morphological analyses revealed significant variation that does not reflect the genetic linages. In addition, investigation of molecular markers combined with comparative morphological analyses showed that radula characters used to distinguish the genera Chaetoderma and Falcidens within Chaetodermatidae do not represent apomorphies, but are a result of ontogenetic changes in C. nitidulum. Together Caudofoveata and Solenogastres, the other group of worm-shaped mollusc, constitute the clade Aplacophora. Because many morphological characters of the aplacophoran molluscs have been presumed to be plesiomorphic for Mollusca, Aplacophora has been regarded as early branching within Mollusca. In recent years, Aplacophora has received much attention as part of Aculifera, a clade grouping Caudofoveata and Solenogastres with Polyplacophora (chitons), as sister to the remaining molluscs. In this thesis, mitochondrial genomes of five species of Caudofoveata and one species of Solenogastres were sequenced, in order to shed light on higher-level relationships within Caudofoveata and their placement within Aculifera. Comparison of mitochondrial gene order among different lineages revealed a highly conserved order of protein coding genes, corresponding to the hypothesized ancestral gene order for Mollusca. Unique arrangements of tRNAs were found for the major lineages of Aculifera, as well as for the families of Caudofoveata. Phylogenetic analyses of amino acid sequences for all 13 mitochondrial protein-coding genes recovered Chaetodermatidae, but not Limifossoridae, monophyletic. Aplacophora was recovered as monophyletic and sister to Polyplacophora

Diversity of Caudofoveata (Mollusca) Around Iceland and Description of Psilodens Balduri sp. n.

The first records from samples from the IceAGE cruise ME85/3 in 2011 include seven species of Caudofoveata with a distribution range in Icelandic waters. From this first cruise of the project, two new records for Iceland have been registered. Psilodens balduri sp. n. is new to science and Falcidens halanychi, with a known distribution in the American North-Atlantic, is new to Iceland. The current study thus increases the number of known caudofoveate species around Iceland to nine.publishedVersio

Leddsnegl i Norge

Leddsnegl (Polyplacophora) er en gruppe marine bløtdyr som lever på alle typer hard bunn. De finnes fra fjæresonen ned til de største havdypene, og flere arter er vanlige å finne på steiner og svaberg på grunt vann. Leddsnegl er vanlige langs Norskekysten, men mange av artene er vanskelig å identifisere og skille fra hverandre. Gjennom prosjektet ‘Norske leddsnegl –diversitet, distribusjon og DNA strekkoding’ har det blitt utarbeidet en oversikt over alle arter leddsnegl i Norge, og forekomst og utbredelse av leddsnegl i norske farvann har blitt kartlagt

Falcidens sagittiferus Salvini-Plawen, 1968: additional data on morphology and distribution (Mollusca, Aplacophora, Caudofoveata)

Falcidens sagittiferus Salvini-Plawen, 1968 is a species of caudofoveate (Chaetodermomorpha) not uncommon in southern Scandinavia. Previous descriptions have however been based mainly on fixed material, and illustrations of sclerites and radula have been incomplete. We here present data from an investigation based on over 70 specimens from Norway (including the type material). Radula, sclerites and living specimens are illustrated.publishedVersio

Phylogenomics of Aplacophora (Mollusca, Aculifera) and a solenogaster without a foot

Recent molecular phylogenetic investigations strongly supported the placement of the shell-less, worm-shaped aplacophoran molluscs (Solenogastres and Caudofoveata) and chitons (Polyplacophora) in a clade called Aculifera, which is the sister taxon of all other molluscs. Thus, understanding the evolutionary history of aculiferan molluscs is important for understanding early molluscan evolution. In particular, fundamental questions about evolutionary relationships within Aplacophora have long been unanswered. Here, we supplemented the paucity of available data with transcriptomes from 25 aculiferans and conducted phylogenomic analyses on datasets with up to 525 genes and 75 914 amino acid positions. Our results indicate that aplacophoran taxonomy requires revision as several traditionally recognized groups are non-monophyletic. Most notably, Cavibelonia, the solenogaster taxon defined by hollow sclerites, is polyphyletic, suggesting parallel evolution of hollow sclerites in multiple lineages. Moreover, we describe Apodomenia enigmatica sp. nov., a bizarre new species that appears to be a morphological intermediate between Solenogastres and Caudofoveata. This animal is not a missing link, however; molecular and morphological studies show that it is a derived solenogaster that lacks a foot, mantle cavity and radula. Taken together, these results shed light on the evolutionary history of Aplacophora and reveal a surprising degree of morphological plasticity within the group.publishedVersio

Improved Efficiency and Robustness in qPCR and Multiplex End-Point PCR by Twisted Intercalating Nucleic Acid Modified Primers

We introduce quantitative polymerase chain reaction (qPCR) primers and multiplex end-point PCR primers modified by the addition of a single ortho-Twisted Intercalating Nucleic Acid (o-TINA) molecule at the 5′-end. In qPCR, the 5′-o-TINA modified primers allow for a qPCR efficiency of 100% at significantly stressed reaction conditions, increasing the robustness of qPCR assays compared to unmodified primers. In samples spiked with genomic DNA, 5′-o-TINA modified primers improve the robustness by increased sensitivity and specificity compared to unmodified DNA primers. In unspiked samples, replacement of unmodified DNA primers with 5′-o-TINA modified primers permits an increased qPCR stringency. Compared to unmodified DNA primers, this allows for a qPCR efficiency of 100% at lowered primer concentrations and at increased annealing temperatures with unaltered cross-reactivity for primers with single nucleobase mismatches. In a previously published octaplex end-point PCR targeting diarrheagenic Escherichia coli, application of 5′-o-TINA modified primers allows for a further reduction (>45% or approximately one hour) in overall PCR program length, while sustaining the amplification and analytical sensitivity for all targets in crude bacterial lysates. For all crude bacterial lysates, 5′-o-TINA modified primers permit a substantial increase in PCR stringency in terms of lower primer concentrations and higher annealing temperatures for all eight targets. Additionally, crude bacterial lysates spiked with human genomic DNA show lesser formation of non-target amplicons implying increased robustness. Thus, 5′-o-TINA modified primers are advantageous in PCR assays, where one or more primer pairs are required to perform at stressed reaction conditions

Clarification of the taxonomic status of Acanthochitona discrepans (Brown, 1827) with new data for the North-East Atlantic Acanthochitona (Polyplacophora, Acanthochitonidae)

The genus Acanthochitona can be easily distinguished from other chitons by having eighteen tufts of bristles on the dorsal side of the densely spiculose girdle. In the North-East Atlantic, five species of this genus have been recognised so far: A. crinita (Pennant, 1777), A. discrepans (Brown, 1827), A. fascicularis (Linnaeus, 1767), A. oblonga Leloup, 1968 and A. pilosa Schmidt-Petersen, Schwabe et Haszprunar, 2015. The nomenclature of A. crinita, A. discrepans and A. fascicularis was confused for a very long time until Kaas (1985) designated type specimens for them and provided a brief key. However, his work lacked detailed descriptions of the three species and some authors doubted that A. discrepans constitutes a separate species. Subsequently, the taxonomic status of A. discrepans has remained unclear.Here, we implemented an integrative approach which combined morphology and molecular evidence to show that Acanthochitona discrepans is, indeed, a valid species and we present re-descriptions for A. crinita, A. discrepans and A. fascicularis

Multiple stakeholders’ perspectives of marine social ecological systems, a case study on the Barents Sea

The Barents Sea ecosystem components and services are under pressure from climate change and other anthropogenic impacts. Following an Ecosystem-based management approach, multiple simultaneous pressures are addressed by using integrative strategies, but regular prioritization of key issues is needed. Identification of such priorities is typically done in a ‘scoping’ phase, where the characterization of the social-ecological system is defined and discussed. We performed a scoping exercise using an open and flexible multi-stakeholder approach to build conceptual models of the Barents Sea social-ecological system. After standardizing vocabulary, a com plex hierarchical model structure containing 155 elements was condensed to a simpler model structure con taining a maximum of 36 elements. To capture a common understanding across stakeholder groups, inputs from the individual group models were compiled into a collective model. Stakeholders’ representation of the Barents Sea social-ecological system is complex and often group specific, emphasizing the need to include social scientific methods to ensure the identification and inclusion of key stakeholders in the process. Any summary or simpli fication of the stakeholders’ representation neglects important information. Some commonalities are highlighted in the collective model, and additional information from the hierarchical model is provided by multicriteria analysis. The collective conceptual stakeholder model provides input to an integrated overview and strengthens prioritization in Ecosystem-based management by supporting the development of qualitative network models. Such models allow for exploration of perturbations and can inform cross-sectoral management trade-offs and prioritiespublishedVersio