Search results for "SPECIATION"
showing 10 items of 370 documents
Confrontation of cryptic diversity and mate discrimination within Gammarus pulex and Gammarus fossarum species complexes.
2014
16 pages; International audience; Freshwater amphipods Gammarus fossarum and Gammarus pulex are widespread in Europe, with some evidence of cryptic diversity in the former. We used DNA barcoding to assess genetic diversity within and among amphipod populations and examined mate discrimination and pre-copulatory pair formation between genetically divergent individuals. Eight distinct G. fossarum and four distinct G. pulex molecular operational taxonomic units (MOTUs) were detected. Among the 33 amphipod populations sampled, 11 contained a single MOTU, 11 had two and 11 were composed of three sympatric MOTUs. Genetic divergences between sympatric MOTUs (G. fossarum and G. pulex MOTUs combined…
Metabolic fate of a bacterial siderophore in Arabidopsis thaliana and Pisum sativum in relationship with iron status in plants
2018
Despite its abundance, iron is weakly bioavailable for organisms due to its poor solubility in soils under aerobic conditions. Therefore, plants and other organisms have evolved mechanisms to efficiently assimilate iron from the soil. Non-grass plants use a strategy (strategy I) based on soil acidification, reduction of the Fe3+ in Fe2+ which incorporated in the roots by iron transporters. We previously showed (Shirley et al., 2011; Vansuyt et al., 2007) that iron nutrition and growth of a strategy I plant could be promoted by the ferric-complex of the pyoverdine (Fe-pvd), a siderophore produced by microorganisms. If pyoverdine was further localized in planta using different immunological t…
Phylogeographical footprints of the Strait of Gibraltar and Quaternary climatic fluctuations in the western Mediterranean: a case study with the grea…
2005
Correspondance: cosson@supagro.inra.fr; International audience; We used mitochondrial cyt b sequences to investigate the phylogenetic relationships of Crocidura russula (sensu lato) populations across the Strait of Gibraltar, western Europe, Maghreb, and the Mediterranean and Atlantic islands. This revealed very low genetic divergence between European and Moroccan populations. The application of a molecular clock previously calibrated for shrews suggested that the separation of European from Moroccan lineages occurred less than 60 000 bp, which is at least 5 million years (Myr) after the reopening of the Strait of Gibraltar. This means that an overwater dispersal event was responsible for t…
Chromosomes and the origins of Apes and Australopithecines
1996
International audience; Comparison of molecular data suggests that the higher apes (Gorilla, Pan) and humankind (Homo) are closely related and that they diverged from the common ancestor through two speciation events situated very closely together in time. Examination of the chromosomal formulas of the living species reveals a paradox on the distribution of mutated chromosomes which can only be re-solved by a model of trichotomic diversification. This new model of divergence from the common ancestor is characterized by the transition from (1) a monotypic phase to (2) a polytypic phase of three sub-species - pre-gorilla, pre-chimpanzee and pre-australopithecine. The quadruped ancestors of Au…
Critics and Criticisms of the Modern Synthesis: the Viewpoint of a Philosopher
1990
International audience
Phenotypic and genetic variability in Forest thrush, Turdus lherminieri at different scales
2012
Understanding the mechanisms underlying population structure is a crucial issue in evolutionary biology and ecology. Identifying the processes driving biodiversity is also of prime interest to draw up guidelines for population management and conservation planning. Level of differentiation depends on a subtle balance between gene flow, genetic drift and natural selection and insight into the relative contribution of these factors can be provided by spatial and temporal patterns of intra-specific phenotypic and genetic variations. Differentiation has mainly been studied in insular systems because i) islands give ideal framework to study divergence in species ii) islands enclosed endemic fauna…
Speciation Studies of Bifunctional 3-Hydroxy-4-Pyridinone Ligands in the Presence of Zn2+ at Different Ionic Strengths and Temperatures
2019
The acid&ndash
Gastrointestinal Helminths of Loggerhead Turtles (Caretta caretta) from the Western Mediterranean: Constraints on Community Structure
1998
Richness and composition of gastrointestinal helminth communities of 54 loggerhead turtles, Caretta caretta, from the western Mediterranean were interpreted from patterns of helminth exchange at 2 host taxonomic scales: exchange between marine turtles and other marine hosts and exchange within turtles. We predicted exchange of the former to be unimportant ecologically and evolutionarily because of the host phylogenetic distance. The absence of records of successful exchange at this host taxonomic scale confirmed that host physiological barriers seem to prevent contemporary parasite transfer between marine turtles and other sympatric hosts. Marine turtles also seem to exhibit an evolutionary…
Molecular and Morphological Differentiation of Two Similar Species of Accacoeliidae (Digenea):Accacladocoelium macrocotyleandA. nigroflavumfrom Sunfi…
2014
In a study of 106 sunfish, Mola mola (L.), from Mediterranean waters, 2,731 worms, belonging to 2 congeneric species of accacoeliids, Accacladocoelium macrocotyle (Diesing, 1858) Robinson, 1934 and Accacladocoelium nigroflavum (Rudolphi, 1819) Robinson, 1934 , were collected from the digestive system. It is often difficult to differentiate between these 2 species as they are sympatric and very similar; in fact, according to previous descriptions, the extent of the vitellarium is the only interspecific difference, described as extending posteriorly to the ovary in A. macrocotyle and as anterior to the anterior testis in A. nigroflavum. However, this diagnostic trait is not always valid; more…
Speciation of organotin compounds in NaCl aqueous solution: interaction of mono-, di- and tri-organotin(IV) cations with nucleotide 5′ monophosphates
2004
Formation constants for complex species of mono-, di- and tri-alkyltin(IV) cations with some nucleotide 5'-monophosphates (AMP, UMP, IMP and GMP) are reported, at T=25°C and at I = 0.16 mol 1 -1 (NaCI). The investigation was performed in the light of speciation of organometallic compounds in natural fluids in the presence of nucleotides whose biological importance is well recognized. The simple and mixed hydrolytic complex species formed in all the systems investigated in the pH range 3-9 are (L = nucleotide; M = organotin cation R x Sn (4-x)+ , with x = 1 to 3): ML + , ML(OH)° and ML(OH) 2 - for the system CH 3 Sn 3+ -L (L = AMP, IMP, UMP); ML 0 and ML(OH)-for the system (C 2 H 5 ) 2 Sn 2+…