Phylogeny and evolution of Monoplacophora and Mollusca

The Mollusca comprises eight classes which are highly diverse in their morphology as well as in molecular appearance. The class level relationships in molluscs were hotly debated during decades and are still under discussion as there is no overall support for one single concept. Morphological and recent phylogenomic studies support the hypothesis of Aculifera (Solenogastres, Caudofoveata and Polyplacophora) and summarize Bivalvia, Cephalopoda, Gastropoda, Monoplacophora and Scaphopoda as the Conchifera. Alternative concepts as Testaria (Bivalvia, Cephalopoda, Gastropoda, Monoplacophora, Scaphopoda and Polyplacophora) or Serialia (Monoplacophora + Polyplacophora) were suggested in the past based on morphological analyses (Testaria) or mainly molecular evidence (Serialia). In order to bring resolution to the class relationships and the early evolution within Mollusca we compiled several comprehensive taxon sets comprising different molecular datasets: combined nuclear and mitochondrial markers obtained via Sanger sequencing (“standard markers”), mitochondrial genomes (analyzing the phylogenetic information of the sequence data as well as comparing the gene arrangements) and phylogenomic data obtained via Next Generation Sequencing. We were able to generate novel data of several species of the elusive class Monoplacophora. Based on the set of standard markers, we found support for Serialia whereas the phylogenomic approach leads to Aculifera and Conchifera, providing first molecular evidence for Monoplacophora sister to Cephalopoda plus other conchiferans; a clade of Gastropoda and Scaphopoda is also supported. Both phylogenetic analyses were used for time estimations and resulted in congruent ages for the molluscan stem (Precambrian) and the diversification of Mollusca (584Mya). We were the first to present a complete mitochondrial genome of a monoplacophoran species ever. Analyzing the mitochondrial gene arrangements we were able to detect potential synapomorphies for Mollusca. Standard marker analyses on comprehensive taxon sets provided novel phylogenetic hypotheses on several molluscan subgroups, such as chitons and gastropods, in particular heterobranchs, challenging mitogenomic approaches and results in the latter. Overall, our studies addressed the phylogeny and evolution of Mollusca and subgroups with a variety of markers and methods and helped to pave the way from using multilocus markers and mitogenomics towards whole genomes

New data from Monoplacophora and a carefully-curated dataset resolve molluscan relationships

Relationships among the major lineages of Mollusca have long been debated. Morphological studies have considered the rarely collected Monoplacophora (Tryblidia) to have several plesiomorphic molluscan traits. The phylogenetic position of this group is contentious as morphologists have generally placed this clade as the sister taxon of the rest of Conchifera whereas earlier molecular studies supported a clade of Monoplacophora +Polyplacophora (Serialia) and phylogenomic studies have generally recovered a clade of Monoplacophora +Cephalopoda. Phylogenomic studies have also strongly supported a clade including Gastropoda, Bivalvia, and Scaphopoda, but relationships among these taxa have been inconsistent. In order to resolve conchiferan relationships and improve understanding of early molluscan evolution, we carefully curated a high-quality data matrix and conducted phylogenomic analyses with broad taxon sampling including newly sequenced genomic data from the monoplacophoran Laevipilina antarctica. Whereas a partitioned maximum likelihood (ML) analysis using site-homogeneous models recovered Monoplacophora sister to Cephalopoda with moderate support, both ML and Bayesian inference (BI) analyses using mixture models recovered Monoplacophora sister to all other conchiferans with strong support. A supertree approach also recovered Monoplacophora as the sister taxon of a clade composed of the rest of Conchifera. Gastropoda was recovered as the sister taxon of Scaphopoda in most analyses, which was strongly supported when mixture models were used. A molecular clock based on our BI topology dates diversification of Mollusca to similar to 546 MYA (+/- 6 MYA) and Conchifera to similar to 540 MYA (+/- 9 MYA), generally consistent with previous work employing nuclear housekeeping genes. These results provide important resolution of conchiferan mollusc phylogeny and offer new insights into ancestral character states of major mollusc clades

On the origin of Acochlidia and other enigmatic euthyneuran gastropods, with implications for the systematics of Heterobranchia

<p>Abstract</p> <p>Background</p> <p>A robust phylogenetic hypothesis of euthyneuran gastropods, as a basis to reconstructing their evolutionary history, is still hindered by several groups of aberrant, more or less worm-like slugs with unclear phylogenetic relationships. As a traditional "order" in the Opisthobranchia, the Acochlidia have a long history of controversial placements, among others influenced by convergent adaptation to the mainly meiofaunal habitats. The present study includes six out of seven acochlidian families in a comprehensive euthyneuran taxon sampling with special focus on minute, aberrant slugs. Since there is no fossil record of tiny, shell-less gastropods, a molecular clock was used to estimate divergence times within Euthyneura.</p> <p>Results</p> <p>Our multi-locus molecular study confirms Acochlidia in a pulmonate relationship, as sister to Eupulmonata. Previous hypotheses of opisthobranch relations, or of a common origin with other meiofaunal Euthyneura, are clearly rejected. The enigmatic amphibious and insectivorous Aitengidae <it>incerta sedis </it>clusters within Acochlidia, as sister to meiofaunal and brackish Pseudunelidae and limnic Acochlidiidae. Euthyneura, Opisthobranchia and Pulmonata as traditionally defined are non-monophyletic. A relaxed molecular clock approach indicates a late Palaeozoic diversification of Euthyneura and a Mesozoic origin of the major euthyneuran diversity, including Acochlidia.</p> <p>Conclusions</p> <p>The present study shows that the inclusion of small, enigmatic groups is necessary to solve deep-level phylogenetic relationships, and underlines that "pulmonate" and "opisthobranch" phylogeny, respectively, cannot be solved independently from each other. Our phylogenetic hypothesis requires reinvestigation of the traditional classification of Euthyneura: morphological synapomorphies of the traditionally defined Pulmonata and Opisthobranchia are evaluated in light of the presented phylogeny, and a redefinition of major groups is proposed. It is demonstrated that the invasion of the meiofaunal habitat has occurred several times independently in various euthyneuran taxa, leading to convergent adaptations previously misinterpreted as synapomorphies. The inclusion of Acochlidia extends the structural and biological diversity in pulmonates, presenting a remarkable flexibility concerning habitat choice.</p

Kräuter für Nutz- und Heimtiere: Ratgeber für die Anwendung ausgewählter Heil- und Gewürzpflanzen

Dieser Ratgeber führt wissenschaftliche Erkenntnisse und traditionelles Hausmittelwissen zusammen, beleuchtet alles Wissenswerte zu über 50 Heilpflanzen und gibt konkrete Anwendungsbeispiele. Ziel ist es, altbewährte Pflanzenanwendungen wieder mehr in die moderne Tierhaltung einzubinden. Der anwenderorientierte Aufbau des Buches ermöglicht es dem Leser, Kenntnisse über die verschiedenen Zubereitungen und Anwendungen von Heilpflanzen zu erwerben und diese in der Praxis einzusetzen. Zubereitung, Aufbewahrung und Anwendung von Kräutern, sowie deren Wirkung und Einsatz bei einzelnen Tierarten werden ausführlich dargestellt. „Die Aufgabe heutiger Wissenschaft ist weniger die Suche nach neuen wirksamen Pflanzen, vielmehr die Überprüfung und Absicherung dieses althergebrachten Wissensschatzes im Lichte moderner Erkenntnisse. Das Autorenteam setzt sich aus jungen engagierten Wissenschaftlern und Tierärzten zusammen. Ihnen ist es ein großes Anliegen, dass die Erkenntnisse der Kräuterheilkunde möglichst vielen Tierhaltern – insbesondere ihren Tieren – von Nutzen sein werden. Es bleibt der Wunsch: die vielen praktischen Anleitungen mögen einen starken Impuls zur Wiederbelebung der Kräuterheilkunde bei Tieren geben.“ Dr. Gerhard Plakol

Age estimates for an adaptive lake fish radiation, its mitochondrial introgression, and an unexpected sister group: Sailfin silversides of the Malili Lakes system in Sulawesi

BACKGROUND: The Malili Lakes system in central Sulawesi (Indonesia) is a hotspot of freshwater biodiversity in the Wallacea, characterized by endemic species flocks like the sailfin silversides (Teleostei: Atherinomorpha: Telmatherinidae) radiation. Phylogenetic reconstructions of these freshwater fishes have previously revealed two Lake Matano Telmatherina lineages (sharpfins and roundfins) forming an ancient monophyletic group, which is however masked by introgressive hybridization of sharpfins with riverine populations. The present study uses mitochondrial data, newly included taxa, and different external calibration points, to estimate the age of speciation and hybridization processes, and to test for phylogeographic relationships between Kalyptatherina from ancient islands off New Guinea, Marosatherina from SW Sulawesi, and the Malili Lakes flock. RESULTS: Contrary to previous expectations, Kalyptatherina is the closest relative to the Malili Lakes Telmatherinidae, and Marosatherina is the sister to this clade. Palaeogeographic reconstructions of Sulawesi suggest that the closer relationship of the Malili Lakes radiation to Kalyptatherina might be explained by a 'terrane-rafting’ scenario, while proto-Marosatherina might have colonized Sulawesi by marine dispersal. The most plausible analysis conducted here implies an age of c. 1.9 My for the onset of divergence between the two major clades endemic to Lake Matano. Diversification within both lineages is apparently considerably more recent (c. 1.0 My); stream haplotypes present in the sharpfins are of even more recent origin (c. 0.4 My). CONCLUSIONS: Sulawesi’s Telmatherinidae have most likely originated in the Sahul Shelf area, have possibly reached the island by both, marine dispersal and island/terrane-rafting, and have colonized the Malili Lakes system from rivers. Estimates for the split between the epibenthic sharpfins and the predominantly pelagic to benthopelagic roundfins in Lake Matano widely coincide with geological age estimates of this rift lake. Diversification within both clades clearly predates hybridization events with stream populations. For Lake Matano, these results support a scenario of initial benthic-pelagic divergence after colonization of the lake by riverine populations, followed by rapid radiation within both clades within the last 1 My. Secondary hybridization of stream populations with the sharpfins occurred more recently, and has thus most likely not contributed to the initial divergence of this benthic species flock

Data from: Age estimates for an adaptive lake fish radiation, its mitochondrial introgression, and an unexpected sister group: Sailfin silversides of the Malili Lakes system in Sulawesi

Background: The Malili Lakes system in central Sulawesi (Indonesia) is a hotspot of freshwater biodiversity in the Wallacea, characterized by endemic species flocks like the sailfin silversides (Teleostei: Atherinomorpha: Telmatherinidae) radiation. Phylogenetic reconstructions of these freshwater fishes have previously revealed two Lake Matano Telmatherina lineages (sharpfins and roundfins) forming an ancient monophyletic group, which is however masked by introgressive hybridization of sharpfins with riverine populations. The present study uses mitochondrial data, newly included taxa, and different external calibration points, to estimate the age of speciation and hybridization processes, and to test for phylogeographic relationships between Kalyptatherina from ancient islands off New Guinea, Marosatherina from SW Sulawesi, and the Malili Lakes flock. Results: Contrary to previous expectations, Kalyptatherina is the closest relative to the Malili Lakes Telmatherinidae, and Marosatherina is the sister to this clade. Palaeogeographic reconstructions of Sulawesi suggest that the closer relationship of the Malili Lakes radiation to Kalypatherina might be explained by a 'terrane-rafting' scenario, while proto-Marosatherina might have colonized Sulawesi by marine dispersal. The most plausible analysis conducted here implies an age of c. 1.9 My for the onset of divergence between the two major clades endemic to Lake Matano. Diversification within both lineages is apparently considerably more recent (c. 1.0 My); stream haplotypes present in the sharpfins are of even more recent origin (c. 0.4 My). Conclusions: Sulawesi's Telmatherinidae have most likely originated in the Sahul Shelf area, have possibly reached the island by both, marine dispersal and island/terrane-rafting, and have colonized the Malili Lakes system from rivers. Estimates for the split between the epibenthic sharpfins and the predominantly pelagic to benthopelagic roundfins in Lake Matano widely coincide with geological age estimates of this rift lake. Diversification within both clades clearly predates hybridization events with stream populations. For Lake Matano, these results support a scenario of initial benthic-pelagic divergence after colonization of the lake by riverine populations, followed by rapid radiation within both clades within the last 1 My. Secondary hybridization of stream populations with the sharpfins occurred more recently, and has thus most likely not contributed to the initial divergence of this benthic species flock

BEAST tree files

BEAST MCC tree files of analyses [A]-[D]

A test of color-based taxonomy in nudibranchs: Molecular phylogeny and species delimitation of the Felimida clenchi (Mollusca: Chromodorididae) species complex

Traditionally, species identification in nudibranch gastropods relies heavily on body color pattern. The Felimida clenchi species complex, a group of brightly colored Atlantic and Mediterranean species in the family Chromodorididae, has a history of exceptional controversy and discussion among taxonomists. The most widely accepted hypothesis is that the complex includes four species (Felimida clenchi, F. neona, F. binza and F. britoi), each with a characteristic body color pattern. In this study, we investigated the taxonomic value of coloration in the Felimida clenchi complex, using molecular phylogenetics, speciesdelimitation analyses (ABGD, GMYC, PTP), haplotype-network methods, and the anatomy of the reproductive system. None of our analyses recovered the traditional separation into four species. Our results indicated the existence of three species, a result inconsistent with previous taxonomic hypotheses. We distinguished an undescribed species of Felimida and redefined the concepts of F. clenchi and F. binza, both highly polychromatic species. For the first time, molecular data support the existence of extreme color polymorphism in chromatic nudibranch species, with direct implications for the taxonomy of the group and its diversity. The polychromatism observed in the F. clenchi complex apparently correlates with the regional occurrence of similar color patterns in congeneric species, suggesting different mimicry circles. This may represent a parallel in the marine environment to the mechanisms that play a major role in the diversification of color in terrestrial and fresh-water chromatic groups, such as heliconian butterflies.Spanish Ministry of Economy and Competitiveness/[CGL2010-17187]//EspañaUniversity of Costa Rica/[810-B1-136]/UCR/Costa RicaCentro de Investigaciones en Ciencias del Mar y Limnología/[] CIMAR/Costa RicaPAPIME-UNAM/[PE207210]//MéxicoPrograma de Biodiversidad Marina de Yucatán/[]/ BDMY/México/[SCHR667/13]/DFG/GermanyMinisterio de Ambiente y Energía/[]/SINAC-MINAET/Costa RicaConsejo Nacional de Ciencia y Tecnología/[108285]/CONACyT-SEMARNAT/México/[]/CEI-MAR journal publication/EspañaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias del Mar y Limnología (CIMAR