Search results for "Systematic"
showing 10 items of 7608 documents
Phylogeny of Early Cretaceous spatangoids (Echinodermata: Echinoidea) and taxonomic implications
2004
A phylogenetic analysis of 36 species provides a test for the taxonomy and the history of Early Cretaceous spatangoids. Most taxonomic units from genera to suborders are consistent with the proposed phylogenetic framework. We retain Hemiasterina, Micrasterina, Hemiasteridae, Schizasteridae, Hemiaster, Heteraster, Mecaster, and Periaster as original monophyletic groups. However, all of these clades originate without the classical apomorphies normally ascribed to them. We suggest a revision of their diagnoses and of the generic attributions of basal species. Some ill-defined, ‘primitive’, and paraphyletic taxa are recognised: Toxaster, Epiaster, Palhemiaster, and Toxasteridae. Even if they do…
THE DEMOSPONGE GENUS LEPTOMITUS and A NEW SPECIES FROM THE MIDDLE CAMBRIAN OF SPAIN
2007
Forty-five specimens of Leptomitus conicus sp. nov. have been collected from the base of the Murero Formation (Caesaraugustan, Middle Cambrian) in the Murero area of Zaragoza, north-east Spain. The new species is a small obconical sponge, which has coarse oxeas forming parallel rods that run the whole length of the specimens in the man- ner typical of the genus. The biostratigraphy and facies of the levels with Leptomitus conicus have been analysed. Palaeoeco- logical information derived from associated trilobites, brachio- pods and ichnofossils shows that L. conicus lived in a soft substrate of a sublittoral environment of low to low ⁄ moderate energy. According to established Cambrian pal…
Contribution of Morphometrics to the Systematics of the Ordovician GenusNeseuretus(Calymenidae, Trilobita) from the Armorican Massif, France
2013
The genusNeseuretusHicks, 1873 is the most abundant trilobite of the Ordovician siltite succession of the Andouillé and Traveusot Formations in the French Armorican massif. The systematics of some species ofNeseuretusis still unclear. Armorican and Iberian domains formed part of a distinctive paleobiogeographical province in the Ordovician and, while fiveNeseuretusspecies were defined in Iberia that follow each other through time, from the Middle to the Upper Ordovician, only oneNeseuretusspecies,N. tristani, has been identified in the Armorican massif so far. The discovery of new fossil deposits in the Ménez-Belair syncline has led to the identification and re-description of threeNeseuretu…
Sponge proteins are more similar to those of Homo sapiens than to Caenorhabditis elegans
2000
We compared 42 phylogenetically conserved proteins from four marine sponges [Porifera] with almost the complete set of Caenorhabditis elegans proteins and all known proteins from humans. The majority of the sponge proteins are significantly more similar to human than to C. elegans orthologues/homologues. This finding reflects the accelerated evolutionary rate in the C. elegans lineage, since sponges split off first from the common ancestor of all multicellular animals. Furthermore, three sponge/human proteins were not found in C. elegans: (2–5)A synthetase, DNA repair helicase and lens βγ -crystallin. Sponges are the source of the most ancient proteins already present in the common ancestor…
Reverse-engineering post-transcriptional regulation of gap genes in Drosophila melanogaster
2013
16 páginas, 6 figuras, 1 tabla
Towards a dendrochronologically refined date of the Laacher See eruption around 13,000 years ago
2020
Highlights • Previous age estimates of the Laacher See Eruptions (LSE) around 12,900 years are still diverging and imprecise. • The combination of dendrochronology, wood anatomy, and 14C measurements holds the potential to establish a precise LSE date. • An absolute calendric date of the LSE would improve the synchronization of European Late Glacial to Holocene archives. Abstract The precise date of the Laacher See eruption (LSE), central Europe’s largest Late Pleistocene volcanic event that occurred around 13,000 years ago, is still unknown. Here, we outline the potential of combined high-resolution dendrochronological, wood anatomical and radiocarbon (14C) measurements, to refine the age …
Cestodes from Hector's beaked whale ( Mesoplodon hectori ) and spectacled porpoise ( Phocoena dioptrica ) from Argentinean waters.
2010
Single individuals of 2 little-known cetacean species, Mesoplodon hectori and Phocoena dioptrica, stranded and died on the coast of Argentina (Buenos Aires and Chubut provinces, respectively) and were studied for the presence of helminths. The cestodes found were described and illustrated using light microscopy. The following cestode taxa were recovered: Tetrabothrius (Tetrabothrius) hobergi n. sp. (several fragmented specimens, at least 1 gravid) and Tetrabothrius (s.l.) sp. 1 (several fragmented immature specimens) from M. hectori, and Tetrabothrius (s.l.) sp. 2 (single fragmented immature specimen) and 2 morphotypes of tetraphyllidean larvae from P. dioptrica. Tetrabothrius (T.) hobergi …
Decoupling Office Energy Efficiency From Employees' Well-Being and Performance: A Systematic Review
2019
Energy efficiency (i.e., the ratio of output of performance to input of energy) in office buildings can reduce energy costs and CO2 emissions, but there are barriers to widespread adoption of energy efficient solutions in offices because they are often perceived as a potential threat to perceived comfort, well-being, and performance of office users. However, the links between offices' energy efficiency and users' performance and well-being through their moderators are neither necessary nor empirically confirmed. The purpose of this study is to carry out a systematic review to identify the existing empirical evidence regarding the relationships between energy-efficient solutions in sustainab…
Corporate social responsibility and sustainability in the tourism sector: A systematic literature review and future outlook
2021
The current study intends to synthesise extant studies addressing corporate social responsibility (CSR) and sustainability in the tourism sector. It employed qualitative content analysis to present the research profile, prominent conceptual, qualitative and quantitative studies, research gaps and future research questions. The review results indicate that research on CSR in tourism is a promising area of study that is growing rapidly. This review captures conceptual, qualitative and quantitative empirical studies and divides them into themes based on two typologies. Typology 1 addresses the direct effect of CSR on employees, customers and business performance. Typology 2 highlights the mode…
The role of extrinsic and intrinsic factors on departure decisions of a long-distance migratory passerine
2013
[EN] Factors determining departure decisions of migrants from a stopover site can be extrinsic and/or intrinsic but the relative role of each of these factors on departure decisions is still poorly known. Date and wind should be the main factors determining departure decisions in a long-distance migrant, which is expected to minimise duration of migration. Date was considered as an intrinsic factor and wind as an extrinsic one. We analysed the capture-recapture data of a long-distance migrant European songbird, the sedge warbler Acrocephalus schoenobaenus,from a stopover site in northern Iberia during the autumn migration period to quantify the relative importance of several factors on emig…