Study Of Molluscs Research Articles

The influence of reclamation to malaco - assemblages of limestone quarry

Quarries fundamentally change the character of the landscape, both in the mined parts and in its immediate surroundings. Inside the mined areas, there are many different types of microbiotopes, their character is very different from the surrounding ecosystem. Destruction of original biotopes is an opportunity for settlement by new plant and animal communities. To monitor these biodiversity changes in the landscape, appropriate groups of organisms are used. Only a bioindicator that is well processable from a taxonomic point of view and its demands on the environment and its distribution are well-known, gives reliable results. For these reasons, less moving molluscs are used in many works. The territory of the southern part of the Devonian limestone of the Moravian Karst is affected by the industrial mining of limestone. There is forest quarry in Lisen, which was ended in 1997 and a few years later reclamation work was started on parts of the mined area. The study of molluscs in this model territory was used to assess the impact of reclamation methods on the malaco - assemblage’s diversity inside the quarry.

The power of islands and of discipleship: Francisco de Arruda Furtado (1854–1887) and the making of a disciple of Darwin

This paper focuses on the biography of the Portuguese naturalist Francisco de Arruda Furtado, born on São Miguel Island, in the Azorean archipelago, in 1854, who became part of an international network of naturalists. Despite his short life, he produced original research on malacology (the study of molluscs), and from his youth Furtado claimed to be a disciple of Darwin. Informed by recent literature reflecting on the resurgence of biography in the history of science, the narrative of Furtado’s life will take into consideration what it meant to be, and the implications of considering oneself, a disciple of Darwin in the nineteenth-century natural sciences. In the history of science, the concept of disciple has often been associated with research schools, but Darwin did not create one and never surrounded himself with young apprentices. In this paper we argue that in Furtado’s case, and in all probability in many others, in addition to being a scientific theory, evolution had the status of a doctrine. As such, Darwinian evolution had a strong ideological and political dimension. By propagating it among lay people it had the potential of changing attitudes individually and socially, while at the same time it provided the scientific foundations for social and political transformation. Consequently, in addition to scientific research based on Darwin’s theory, Furtado deeply engaged in proselytizing the natural sciences and Darwinian evolution, becoming representative of the importance of Darwin’s disciples in Furtado’s sense, in the reception and endorsement of evolution around the world, with repercussions beyond natural history.

9. Seashells in the Jordanian Desert: a Cross-Cultural Analysis

The remains of ancient communities have been found at Wadi Ramm and Humayma, Jordan in the midst of what is now the Jordanian desert. In past times these sites were located along caravan routes and were populated by Nabataean, Roman, Byzantine, and early Islamic peoples. Despite the fact that these sites are located tens of kilometers from the seashore, seashells are frequently found in the layers associated with the different population groups. As of yet, shells from the 1996-1997 excavations at Wadi Ramm and from the 2008-2010 excavations at Humayma have not received in depth analyses allowing them to be correctly identified, quantified, and associated with significant archaeological contexts. Archaeomalacology (the study of molluscs in archaeological contexts) is a vital part of deciphering ancient human diet and activity. It is also critical in determining past environments and transportation systems. Clearly these shells came from the sea, but how did they get to these remote desert locales? Based on the preliminary descriptions provided by the field excavators, the photographs of the Wadi Ramm shells, and the actual Humayma shells which are at Queen’s, I am creating a catalogue to identify, describe, and quantify the variety of mollusc species present. This catalogue incorporates all of the significant data in one place, thus allowing me to look for patterns in the frequency, condition, and probable function of the shells. This analysis will lead to a better understanding of the diet and cultural practices of the different ancient inhabitants at Wadi Ramm and Humayma.

The opisthobranch gastropods (Mollusca: Heterobranchia) from Venezuela: an annotated and illustrated inventory of species

The Caribbean waters of Venezuela are composed by a large variety of habitats, with over 2800 km of coastline, islands, and islets. This area is a transitional zone between two main biogeographic provinces, the Caribbean and the Brazilian, separated by the fresh water outflows of the Orinoco and Amazon rivers, and is therefore expected to be an area of high species diversity. However, concerning the study of molluscs, Venezuela is probably the poorest known region in the Caribbean. The best compilation of opisthobranch species known in Venezuela was produced almost a decade ago, mentioning the occurrence of 57 species, plus seven determined only to genus level. In this work, 134 species are reported for Venezuela (71 are illustrated), representing about 40 % of the entire diversity of opisthobranchs known in the Caribbean. Among the species occurring in Venezuela, 49 have here the southern limit of their distribution range and only one the northern limit. Forty-six species are recorded for the first time to the country and one is a new record for the Caribbean Sea, namely Placida cremoniana. In addition, the distribution and ecology of the species are given based in literature and new data.

Molluscs from a shallow-water whale-fall and their affinities with adjacent benthic communities on the Swedish west coast

We conducted a species-level study of molluscs associated with a 5-m long carcass of a minke whale at a depth of 125 m in the Kosterfjord (North Sea, Sweden). The whale-fall community was quantitatively compared with the community commonly living in the surrounding soft-bottom sediments. Five years after the deployment of the dead whale at the sea floor, the sediments around the carcass were dominated by the bivalve Thyasira sarsi, which is known to contain endosymbiotic sulphur-oxidizing bacteria, while background sediments were dominated by another thyasirid, T. equalis, less dependent on chemosynthesis for its nutrition. The Kosterfjord samples were further compared at the species level with mollusc abundance data derived from the literature, including samples from different marine settings of the west coast of Sweden (active methane seep, fjords, coastal and open marine environments). The results show high similarity between the Kosterfjord whale-fall community and the community that developed in one of the Swedish fjords (Gullmar Fjord) during hypoxic conditions. This study indicates that at shallow-water whale-falls, the sulphophilic stage of the ecological succession is characterized by generalist chemosynthetic bivalves commonly living in organic-rich, sulphidic environments.

Phylogenetic information of genes, illustrated with mitochondrial data from a genus of gastropod molluscs

A critical assessment of sequencing markers is desirable to ensure that they are appropriate for the specific questions that are to be addressed. This consideration is particularly important where the data set will be used in highly sensitive analyses such as molecular clock studies. However, there is no standard practice for marker assessment. We examined the mitochondrial DNA sequences of a genus of marine molluscs to assess the relative phylogenetic signal of a number of genes using an extension of splits-based spectral analysis. With a data set of almost 8 kb of DNA sequences from the mitochondrial genome of a lineage of marine molluscs, we compared the phylogenetic information content of six protein coding, two ribosomal DNA, and 12 transfer RNA genes. Split-support graphs were used to identify which genes contributed a relatively low signal-to-noise ratio of phylogenetic information. We found that cox2 and atp8 did not perform well for reconstruction at the within-genus level for this lineage. Consideration of nested subsets of taxa improved the resolution of relationships among closely related species by reducing the time frame over which evolutionary processes have occurred, allowing a better fit for models of DNA substitution. Through this fine-tuning of available data it is possible to generate phylogenetic reconstructions of increased robustness, for which there is a greater understanding of the underlying signals in the data. We recommend a suitable mitochondrial DNA fragment and new primers for intergeneric studies of molluscs, and outline a general pipeline for phylogenetic analysis. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104, 770–785.

From Poe to Ponder…and Lindberg: Introduction to the Symposium “Molluscs as Models in Evolutionary Biology”*

Known to students of our profession and concisely summarized most recently in Ponder and Lindberg (2008), Mollusca are, with an estimated 200,000 living species, one of the largest animal phyla, second only to the arthropods. The remarkably rich fossil record of molluscs throws light back into the earliest Cambrian revolution 543 million years ago, and ever since then we fi nd them in nearly every ecosystem on Earth. The classes of living and fossil molluscs comprise an array of diverse animals with the most varied body plans, ranging from minute worm-like animals dwelling between sand grains on the beach to giant squids in the deep sea, and from microscopic snails in leaf-litter to giant clams in coral reefs. As objects of fascination, function, and food, molluscs play important roles in many cultures and societies. They include many taxa of immense economic signifi cance, such as oysters, scallops, and squids; some bivalves produce precious pearls, and some snails carry diseases that infect millions of people, especially in the tropics. Yet we feel that it is not only a curious fact in the history of science, but, unfortunately enough, much more a symptomatic indication of our discipline that it was not a professional naturalist or scientist with an interest in malacology, but the poet Edgar Allen Poe (1809-1849), who formulated an idea with much future. Poe was among the fi rst to recognize and explicitly recommend that the study of molluscs requires a combined analysis, which in his times meant reconciling a classifi cation based on hard shells with evidence from soft body anatomy (see details on this in the opening remarks to the symposium by Glaubrecht (2009)). This synthetic idea was long ignored by conchologists, who continued to classify molluscs almost exclusively based on features of their shell, while neglecting the soft body and the biological information that it holds. As a consequence, for a long time we knew few hard facts, for example, about the evolution and phylogeny of these soft-bodied animals but instead had much speculation by self-proclaimed authorities in the fi eld. In addition, most contributions in malacology long centered around morphology, anatomy, and in particular phylogenetic relationships within and among constituent taxa. Only rarely have molluscs been utilized explicitly as models for the study of the general aspects of evolutionary biology. However, molluscs, with their many features and facets, are highly suitable for providing some fundamental insights into the mechanisms of the genesis of biodiversity, its pattern in historical biogeography, and the underlying processes of speciation and radiation. An increasing number of recent studies and publications on molluscs reveal this rich potential. Therefore, it was the aim of this symposium on molluscs as models in evolutionary biology, held during the World Congress of Malacology (WCM) in Antwerp from the 15th to 20th July 2007 (jointly organized by Unitas Malacologia and the American Malacological Society), to bring together experts and their expertise to provide—based on molluscs— some of those fundamental studies, and to show avenues for using data that are of relevance for evolutionary biology. With 43 talks over more than two full days of sessions (plus several posters), this symposium was the largest at the Antwerp WCM. Following the introduction, two invited keynotes or plenary lectures were given, one by Suzanne Williams and David Reid (on global pattern of diversity and speciation) and one by Thomas Wilke and Christian Albrecht (on genesis of biodiversity, focusing on ancient lakes). Other lectures covered a wide array of topics ranging from biogeography, shell morphology and evolution, molecular phylogenetics, radiations and extinctions as documented in the fossil record, to mitogenomics, and aspects of development and reproduction. From all these presentations, a selection of eleven contributions were made, and we invited the authors to work out their main subject as exemplars for their specifi c area of research, viewed from their individual perspective. Subsequently, eight of the original speakers have been able to provide manuscripts for the American Malacological Bulletin.

Mutagen content and metabolic activation of promutagens by molluscs as biomarkers of marine pollution

Organisms combat pollutants by inducing biotransformation pathways, which can be used for biomonitoring. Several parameters—biomarkers—change in stressed organisms or populations at different organisation levels. Molecular or cellular biomarkers are early-warning indicators of pollution. Xenobiotics are first biotransformed by phase I enzymes and then conjugated with endogenous metabolites by phase II enzymes. Many organic xenobiotics are initially biotransformed by cytochrome P4501A1; in mammals, it is induced by pollutants via Ah receptor, although in marine invertebrates, its inducibility is much more equivocal. Metallothioneins are small Cys-rich proteins which bind transition metals; they detoxicate pollutant metals and are clearly induced in metal-exposed marine invertebrates. Some pollutants are genotoxins or can be converted into them. Determination of mutagens in bivalve molluscs following extraction with solvents and assay of mutagenicity with bacterial tests is a useful biomarker for marine pollution. While some pollutants are directly mutagenic, others are only mutagenic after they are activated to mutagenic derivatives by monooxygenases or conjugative enzymes. Many of these catalysts are induced by xenobiotics; thus, increased activation of known promutagens can be used as biomarker of environmental pollution. Bioactivation of promutagens requires the simultaneous action of different pathways, thus, reproducing more closely the in vivo situation than the specific assay of individual biotransforming enzymes. Study of molluscs with different pollution levels indicates that polluted animals have higher capacity to activate 2-aminoanthracene and contain more apolar mutagens than those from reference areas.

Late Pliocene climate change 3.4-2.3 Ma: paleoceanographic record from the Yabuta Formation, Sea of Japan

Late Pliocene paleoceanographic changes in the Sea of Japan between 3.4 and2.3 Ma were investigated through study of molluscs, diatoms, and ostracodes from the Yabuta Formation in Toyama Prefecture. The period 3.4−2.7 Ma was characterized by relatively high sea level and cool water benthic faunas. A progressive paleoceanographic shift towards colder oceanic conditions and lower sea level occurred beginning near 2.7 Ma, intenifying about 2.5 Ma, when important changes in ostracode and molluscan faunas occurred. Between 2.7 and 2.3 Ma, eight glacial events can be inferred based on drops in sea level of 50–60 m and increasing proportions of cold, shallow water ostracode species whose modern ecology and zoogeography indicate colder winter water temperatures (3–4°C). The glacial events between 2.5 and 2.3 Ma were the most intense. Preliminary interpretation of the faunal and oceanographic events of the Yabuta Formation suggests that they correspond to Northern Hemispheric cooling also known from North Atlantic deep-sea oxygen isotope, IRD, and planktic foraminiferal records, North Pacific diatom and radiolarian record, and the Chinese loess sequences. The eight glacial events may record a 41,000-yr obliquity cycle which characterized other late Pliocene climate proxy records. Inferred sea level drops near 2.5−2.3 Ma of about 50–60 m provide direct evidence from an ocean margin setting that supports deep sea oxygen isotopic evidence indicating major changes in global ice volume changes.

Paléoenvironnement tardiglaciaire et holocène des lacs de Pelléautier et Siguret (Hautes-Alpes, France). III. Les faunes malacologiques de Pelléautier et de Siguret (Alpes Duranciennes, France)

The study of Molluscs from Pelléautier and Siquret was made difficult because there was no sufficient material available. At Pelléautier, the dominant constant species is Valvata cristata, whereas it has not been found at Siguret, where the most abundant taxon is Pisidium, which indicates colder waters and a sparser aquatic vegetation. One should be prudent in inferring climatic conclusions from qualitative and quantitative variations of fauna : at Pelléautier, the presence of Pisidium lilljeborgi at 6,15 m indicates more severe conditions than the present ones ; the greatest amount of individuals between 400 and 405 cm may point out to a climatic improvement ; however, at Siguret the species is most abundant during a phase of climatic deterioration.

Les Mollusques du gisement pléistocène moyen des Abîmes de la Fage à Noailles (Corrèze)

The study of molluscs has been made on rudimentary shells of Limacidae and Gastropoda gathered during the excavation or during the sorting of the deposit after it has been washed. Thus it is almost sure the population studied here is not quite faithful to reality. However, the examination of the remains has been undertaken not only from the point of view of association but also from the morphology of the shell, by comparison with the present-day species living in the neighbourhood of la Fage. The only layers 2, 3 and 5 have yielded, with remains of vertebrates, malacological material enough to give yet some idea about landscape during the ages when these layers were deposited : meadows interrupted by hedges, groves and rocky outcrops. The climate was rather wet but certainly warmer than it is to day under this latitude.

Molluscs Studies in the Structure, Physiology and Ecology of Molluscs V. Fretter

Molluscs Get access Studies in the Structure, Physiology and Ecology of Molluscs, edited by Fretter V., Published for the Zoological Society of London by Academic Press, Inc., New York & London, 1968, 377 p., illus., $15.00 (68–17680). John D. Davis John D. Davis Smith College, Northampton, Mass. Search for other works by this author on: Oxford Academic Google Scholar BioScience, Volume 19, Issue 10, October 1969, Page 944, https://doi.org/10.2307/1294735 Published: 01 October 1969