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showing 10 items of 6284 documents
Evolution of mammal tooth patterns: new insights from a developmental prediction model.
2009
14 pages.; International audience; The study of mammalian evolution is often based on insights into the evolution of teeth. Developmental studies may attempt to address the mechanisms that guide evolutionary changes. One example is the new developmental model proposed by Kavanagh et al. (2007), which provides a high-level testable model to predict mammalian tooth evolution. It is constructed on an inhibitory cascade model based on a dynamic balance of activators and inhibitors, regulating differences in molar size along the lower dental row. Nevertheless, molar sizes in some mammals differ from this inhibitory cascade model, in particular in voles. The aim of this study is to point out arvi…
Reappraisal of ‘chronospecies' and the use of Arvicola (Rodentia, Mammalia) for biochronology.
2008
13 pages; International audience; The water vole, genus Arvicola, is characterised by a broad geographic distribution throughout Europe and is widespread during the late Middle and Upper Pleistocene. This genus is used as a major biostratigraphic tool within the Quaternary. Specific determinations using the Schmelzband-Differenzierung-Quotient or SDQ have identified many chronospecies within the fossil species Arvicola cantiana (Hinton, 1910). As SDQ calculation remains limited, this study reappraises the Arvicola genus in terms of morphodiversity and morphospace using outline analysis which takes into account the tooth as a whole. Outline analysis suggests that one single species of Arvico…
ILTER – The International Long-Term Ecological Research Network as a Platform for Global Coastal and Ocean Observation
2019
International audience; Understanding the threats to global biodiversity and ecosystem services posed by human impacts on coastal and marine environments requires the establishment and maintenance of ecological observatories that integrate the biological, physical, geological, and biogeochemical aspects of ecosystems. This is crucial to provide scientists and stakeholders with the support and knowledge necessary to quantify environmental change and its impact on the sustainable use of the seas and coasts. In this paper, we explore the potential for the coastal and marine components of the International Long-Term Ecological Research Network (ILTER) to fill this need for integrated global obs…
Molecular phylogeny of the marine dinoflagellate genus Heterodinium (Dinophyceae)
2012
The dinoflagellate genus Heterodinium has unusual morphological characters such as a mid-ventral intercalary plate with a pore, a small plate in the left side of the dorsal epitheca, three antapical plates, and a well-developed anterior cingular list. We obtained the first SSU rDNA sequences from single cells of six species of Heterodinium from Mediterranean coastal and open waters. They included the type species H. scrippsii and H. rigdeniae and representatives of the other subgenera, Sphaerodinium (H. doma, H. milneri, H. globosum) and Platydinium (H. pavillardii). SSU rDNA phylogeny showed that Heterodinium spp. formed a well-supported monophyletic group (100% bootstrap support) composed…
Does an ant-dispersed plant, Viola reichenbachiana, suffer from reduced seed dispersal under inundation disturbances?
2008
Many plant species use ants as seed dispersers. This dispersal mode is considered to be susceptible to disturbances, but the effect of natural, small-scale disturbances is still unknown. We investigated how small-scale disturbances due to inundation affect seed dispersal in Viola reichenbachiana, a dominant myrmecochorous herb in riparian forests. Inundation disturbances were high in depressions and low on hillocks of the forest floor. We found that V reichenbachiana was similarly abundant at highly and less disturbed sites, contrary to other, non ant-dispersed species. We also found that the motivation of ants to disperse seeds was higher at highly disturbed sites. Nevertheless, the number…
Molecular Phylogeny of Tintinnid Ciliates (Tintinnida, Ciliophora)
2012
We investigated the phylogeny of tintinnids (Ciliophora, Tintinnida) with 62 new SSU-rDNA sequences from single cells of 32 marine and freshwater species in 20 genera, including the first SSU-rDNA sequences for Amphorides, Climacocylis, Codonaria, Cyttarocylis, Parundella, Petalotricha, Undella and Xystonella, and 23 ITS sequences of 17 species in 15 genera. SSU-rDNA phylogenies suggested a basal position for Eutintinnus, distant to other Tintinnidae. We propose Eutintinnidae fam. nov. for this divergent genus, keeping the family Tintinnidae for Amphorellopsis, Amphorides and Steenstrupiella. Tintinnopsis species branched in at least two separate groups and, unexpectedly, Climacocylis branc…
Sucrose amendment enhances phytoaccumulation of the herbicide atrazine in Arabidopsis thaliana.
2006
International audience; Growth in the presence of sucrose was shown to confer to Arabidopsis thaliana (thale cress or mustard weed) seedlings, under conditions of in vitro culture, a high level of tolerance to the herbicide atrazine and to other photosynthesis inhibitors. This tolerance was associated with root-to-shoot transfer and accumulation of atrazine in shoots, which resulted in significant decrease of herbicide levels in the growth medium. In soil microcosms, application of exogenous sucrose was found to confer tolerance and capacity to accumulate atrazine in Arabidopsis thaliana plants grown on atrazine-contaminated soil, and resulted in enhanced decontamination of the soil. Applic…
New insights into Late Devonian vertebrates and associated fauna from the Cuche Formation (Floresta Massif, Colombia)
2019
New vertebrate remains are reported from the Late Devonian (?Frasnian) Cuche Formation of northeastern Colombia, including a new taxon of antiarch placoderm (Colombialepis villarroeli, gen. et sp. nov., previously reported as Asterolepis) and a new taxon of arthrodiran placoderm (Colombiaspis rinconensis, gen. et sp. nov.). We also report evidence of a stegotrachelid actinopterygian, a diplacanthid acanthodian (cf. Florestacanthus morenoi), a second antiarch placoderm (Bothriolepis sp.), a putative megalichthyid, and a putative tristichopterid. The absence of typical Euramerican markers, e.g., Asterolepis and Strepsodus, in this assemblage suggests that faunal interchange between Euramerica…
Rodents and palaeogenetics: new perspectives.
2008
10 pages; Rodents are the most diversified mammalian order (484 extant genera including 2277 species), and they have a worldwide distribution. Palaeontological, morphological and molecular data have greatly helped to resolve their systematics and evolutionary history. However, some discrepancies remain between palaeontologists and molecular biologists. New techniques in molecular biology, and especially in palaeogenetics, allow us to have direct access to the hereditary material of extinct organisms, and they can compensate for some morphological limits. Unfortunately, few studies are dealing with rodent palaeogenetics, despite the amount of museum and fossil material available. Here, we re…
Trophic ecology of a Late Pleistocene early modern human from tropical Southeast Asia inferred from zinc isotopes
2021
Tam Pà Ling, a cave site in northeastern Laos, has yielded the earliest skeletal evidence of Homo sapiens in mainland Southeast Asia. The reliance of Pleistocene humans in rainforest settings on plant or animal resources is still largely unstudied, mainly due to poor collagen preservation in fossils from tropical environments precluding stable nitrogen isotope analysis, the classical trophic level proxy. However, isotopic ratios of zinc (Zn) in bioapatite constitute a promising proxy to infer trophic and dietary information from fossil vertebrates, even under adverse tropical taphonomic conditions. Here, we analyzed the zinc isotope composition (66Zn/64Zn expressed as δ66Zn value) in the en…