Taxon

Résumé

thumb|upright=1.5|Les taxons sont des entités nommées, constituées d'organismes vivants regroupés et identifiés par la taxonomie : 1-Règne 2-Embranchement 3-Classe 4-Ordre 5-Famille 6-Genre 7-Espèce Un taxon est une entité conceptuelle qui regroupe tous les organismes vivants possédant en commun certains caractères taxinomiques ou diagnostiques bien définis. Le terme dérive du terme taxonomie par troncation, et non directement du grec / táxis, « placement », « mise en ordre ». L'espèce constitue le taxon de base de la classification systématique. Plus le rang du taxon est élevé et plus le degré de ressemblance des individus concernés est faible, c'est-à-dire plus le nombre de caractères que des plantes, animaux, champignons, bactéries ou chromistes ont en commun entre eux est faible, et inversement. Dans les classifications linnéennes, les caractères d'un taxon sont réputés homogènes en fonction de leur rang taxinomique, leur valeur taxinomique relative étant laissée à l'appréciati

Source officielle

https://fr.wikipedia.org/wiki/Taxon

À propos de ce résultat

Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.

Publications associées (28)

Publications associées

Chargement

Personnes associées (5)

Personnes associées

Chargement

Unités associées (2)

Unités associées

Chargement

Concepts associés (50)

vignette|350px|La classification classique du vivant classe les êtres vivants selon une hiérarchie de groupes de plus en plus vastes. La taxonomie ou taxinomie est une branche des sciences naturelles

vignette| redresse=1.2| L'espèce est l'unité de base de la classification du vivant. Dans les sciences du vivant, l’espèce (du latin species, « type » ou « apparence ») est le taxon de base de la sys

thumb|La buse montagnarde appartient au genre Buteo. Son nom d'espèce complet est Buteo oreophilus. En systématique, le genre est un rang taxinomique (ou taxonomique) qui regroupe un ensemble d'espèce

Afficher plus

Concepts associés

Chargement

Cours associés (2)

Cours associés

Chargement

Séances de cours associées (2)

Séances de cours associées

Chargement

Bacterial diversity in 16S ribosomal DNA and reverse-transcribed 16S rRNA clone libraries originating from the heavy metal-contaminated rhizosphere of the metal-hyperaccumulating plant Thlaspi caerulescens was analysed and compared with that of contaminated bulk soil. Partial sequence analysis of 282 clones revealed that most of the environmental sequences in both soils affiliated with five major phylogenetic groups, the Actinobacteria, alpha-Proteobacteria, beta-Proteobacteria, Acidobacteria and the Planctomycetales. Only 14.7% of all phylotypes (sequences with similarities >97%), but 45% of all clones, were common in the rhizosphere and the bulk soil clone libraries. The combined use of rDNA and rRNA libraries indicated which taxa might be metabolically active in this soil. All dominant taxa, with the exception of the Actinobacteria, were relatively less represented in the rRNA libraries compared with the rDNA libraries. Clones belonging to the Verrucomicrobiales, Firmicutes, Cytophaga-Flavobacterium-Bacteroides and OP10 were found only in rDNA clone libraries, indicating that they might not represent active constituents in our samples. The most remarkable result was that sequences belonging to the Actinobacteria dominated both bulk and rhizosphere soil libraries derived from rRNA (50% and 60% of all phylotypes respectively). Seventy per cent of these clone sequences were related to the Rubrobacteria. subgroups 2 and 3, thus providing for the first time evidence that this group of bacteria is probably metabolically active in heavy metal-contaminated soil.

Wiley-Blackwell2003

Chargement

Exposing planktonic source communities from stream and floodplain ecosystems to differing hydraulic environments revealed strong selective hydraulic pressures but only minor founder effects on the differentiation of attached biofilms and suspended aggregates and their biodiversity dynamics. Key taxa with a coherent phylogenetic underpinning drove this differentiation. Few resident and phylogenetically related taxa formed the backbone of biofilm communities, whereas numerous taxa with lower temporal turnover characterized aggregate communities. Fundamental ecological differences between biofilms and aggregates exist and local hydraulics drives the distribution of microbial diversity along the fluvial continuum

2016

Chargement

Pollen productivity estimates and relevant source area of pollen for selected plant taxa in a pasture woodland landscape of the Jura Mountains (Switzerland)

Alexandre Buttler, Pascal Vittoz

Relevant source area of pollen (RSAP) and pollen productivity for 11 key taxa characteristic of the pasture woodland landscape of the Jura Mountains, Switzerland, were estimated using pollen assemblages from moss polsters at 20 sites. To obtain robust pollen productivity estimates (PPEs), we used vegetation survey data at a fine spatial-resolution (1 x 1 m(2)) and randomized locations for sampling sites, techniques rarely used in palynology. Three Extended R value (ERV) submodels and three distance-weighting methods for plant abundance calculation were applied. Different combinations of the submodels and distance-weighting methods provide slightly different estimates of RSAP and PPEs. Although ERV submodel 1 using 1/d (d = distance in meters) best fits the dataset, PPE values for heavy pollen types (e.g. Abies) were sensitive to the method used for distance-weighting. Taxon-specific distance-weighting methods, such as Prentice's model, emphasize the intertaxonomic differences in pollen dispersal and deposition, and are thus theoretically sound. For the dataset obtained in this project, Prentice's model was more appropriate than other distance-weighting methods to estimate PPEs. Most of the taxa have PPEs equal to (Fagus, Plantago media and Potentilla-type), or higher (Abies, Picea, Rubiaceae and Trollius europaeus) than Poaceae (PPE = 1). Acer, Cyperaceae, and Plantago montana-type are low pollen producers. This set of PPEs will be useful for reconstructing heterogeneous, mountainous pasture woodland landscapes from fossil pollen records. The RSAP for moss polsters in this semi-open landscape region is ca. 300 m.

Springer Verlag2008

Chargement