Search results for "evolutionary biology"
showing 10 items of 3886 documents
Introduction et dispersion d'une espèce envahissante : le cas de l'ambroisie à feuilles d'armoise (Ambrosia artemisiifolia L.) en France
2011
National audience; Ambrosia artemisiifolia L. (common ragweed) was accidentally introduced into France in the 1860s. Its single vector of introduction in Europe was red clover seeds (Trifolium pratense L.), probably coming from Pennsylvania, United States at the time. A. artemisiifolia was later introduced into France in many places and at different times. This species has no natural or effective seed dispersal mechanisms and the spread of this weed in the territory is ensured by human activities that carry the seeds and create disturbed environments favourable to its development. It is now established in the Rhone Valley and a number of different factors (cropping system evolution, climate…
Biodiversity and characterization of arbuscular mycorrhizal fungi at the molecular level
1994
Biodiversity within a biological group provides the basis for distinguishing members into genera and species according to taxonomic criteria, and between individuals within a species depending on more detailed differences at the genetic level. Diversity between species occurs after a genetic barrier has been created either by a geographic or genetic impedance of gene flow. Divergence can continue by nucleotide substitutions and by mutations in a broader sense (deletions, translocations, duplications), and resulting diversity can be evaluated at the molecular level and used as a phylogenetic character. Diversity at the subspecies level is a function of both mutation rates and gene flow betwe…
Qualité et performance de plants de Douglas soumis à différentes contraintes hydriques
1999
An experiment was carried out on 12 Douglas fir seedlings lots that were 3 years old and had all originated from the same seed lot. Treatments consisted in combining stock type with three different height to diameter ratios, storage duration and method (long at 2°C or short in various conditions), and protection from desiccation (by bagging or not). Seedling lots were assessed at planting by root electrolyte leakage (REL), root moisture content (RMC) and predawn shoot water potential (Ywp). They were planted simultaneously in well-watered or water-stressed conditions. Performance level was based on survival and height growth at the end of the growing season. Slender seedlings not bagged had…
Molecular characterization of cyclic and obligate parthenogens in the aphid Rhopalosiphum padi (L.)
1996
Holocyclic clones of the aphid Rhopalosiphum padi (L.) reproduce by cyclic parthenogenesis, whereas anholocyclic individuals are obligate parthenogens. Mitochondrial DNA (mtDNA) and random amplified polymorphic DNA markers in R . padi as well as plasmid DNA markers of its bacterial endosymbiont, Buchnera aphidicola , were examined to determine the extent of genetic divergence between clones with these differing breeding systems. These analyses revealed that cyclically parthenogenetic lineages possessed differing mtDNA and plasmid haplotypes than most obligately asexual clones. The extent of sequence divergence between these maternally inherited molecules suggests a relatively ancient origin…
Mollusc shellomes: Past, present and future.
2020
13 pages; International audience; In molluscs, the shell fabrication requires a large array of secreted macromolecules including proteins and polysaccharides. Some of them are occluded in the shell during mineralization process and constitute the shell repertoire. The protein moieties, also called shell proteomes or, more simply, 'shellomes', are nowadays analyzed via high-throughput approaches. These latter, applied so far on about thirty genera, have evidenced the huge diversity of shellomes from model to model. They also pinpoint the recurrent presence of functional domains of diverse natures. Shell proteins are not only involved in guiding the mineral deposition, but also in enzymatic a…
Assessing short- and long-term repeatability and stability of personality in captive zebra finches using longitudinal data
2012
11 pages; International audience; Assessing behavioural consistency is crucial to understand the evolution of personality traits. In the present study, we examined the short- and long-term repeatability and stability of two unrelated personality traits - exploratory tendencies and struggling rate - using captive female zebra finches (Taeniopygia guttata). We performed two experimental sessions of behavioural tests with a 7-mo interval, which represents up to one quarter of a zebra finch's life expectancy. We showed that, overall, exploratory tendencies and struggling rate were significantly repeatable in the short term. However, only exploratory tendencies were repeatable in the long term. …
A mathematical method for determining genome divergence and species delineation using AFLP.
2002
The delineation of bacterial species is presently achieved using direct DNA-DNA relatedness studies of whole genomes. It would be helpful to obtain the same genomically based delineation by indirect methods, provided that descriptions of individual genome composition of bacterial genomes are obtained and included in species descriptions. The amplified fragment length polymorphism (AFLP) technique could provide the necessary data if the nucleotides involved in restriction and amplification are fundamental to the description of genomic divergences. Firstly, in order to verify that AFLP analysis permits a realistic exploration of bacterial genome composition, the strong correspondence between …
Population Structure and Comparative Genome Hybridization of European Flor Yeast Reveal a Unique Group of Saccharomyces cerevisiae Strains with Few G…
2014
Wine biological aging is a wine making process used to produce specific beverages in several countries in Europe, including Spain, Italy, France, and Hungary. This process involves the formation of a velum at the surface of the wine. Here, we present the first large scale comparison of all European flor strains involved in this process. We inferred the population structure of these European flor strains from their microsatellite genotype diversity and analyzed their ploidy. We show that almost all of these flor strains belong to the same cluster and are diploid, except for a few Spanish strains. Comparison of the array hybridization profile of six flor strains originating from these four co…
Harnessing the biodiversity value of Central and Eastern European farmland
2015
A large proportion of European biodiversity today depends on habitat provided by low‐intensity farming practices, yet this resource is declining as European agriculture intensifies. Within the European Union, particularly the central and eastern new member states have retained relatively large areas of species‐rich farmland, but despite increased investment in nature conservation here in recent years, farmland biodiversity trends appear to be worsening. Although the high biodiversity value of Central and Eastern European farmland has long been reported, the amount of research in the international literature focused on farmland biodiversity in this region remains comparatively ti…
Effects of density, species interactions, and environmental stochasticity on the dynamics of British bird communities
2022
Our knowledge of the factors affecting species abundances is mainly based on time-series analyses of a few well-studied species at single or few localities, but we know little about whether results from such analyses can be extrapolated to the community level. We apply a joint species distribution model to long-term time-series data on British bird communities to examine the relative contribution of intra- and interspecific density dependence at different spatial scales, as well as the influence of environmental stochasticity, to spatiotemporal interspecific variation in abundance. Intraspecific density dependence has the major structuring effect on these bird communities. In addition, envi…