Insight into the phylogeny of African Clariidae (Teleostei, Siluriformes): implications for their body shape evolution, biogeography, and taxonomy.

The phylogenetic relationships among Clariidae species (Teleostei, Siluriformes) were assessed using 563 nucleotides of the cytochrome b mitochondrial gene. We included 32 Clariidae species representative of seven genera in our analysis. Hetropneustes fossilis (Heteropneustidae) and Clarotes laticeps (Claroteidae) were used as outgroups.

Genetic differentiation at nuclear and mitochondrial loci among large white-headed gulls: sex-biased interspecific gene flow?

We measured genetic differentiation among species of large white-headed gulls using mitochondrial (cytochrome b haplotypes) and nuclear (microsatellites) markers. Additional information was added using a previously published study of allozymes on the same species. Levels of differentiation among species at nuclear markers are much lower than would be expected for avian species and are not concordant with the level of differentiation in mitochondrial markers.

Large discrepancies in differentiation of allozymes, nuclear and mitochondrial DNA loci in recently founded Pacific populations of the pearl oyster Pinctada margaritifera.

This study presents a comparative analysis of population structure applied to the pearl oyster (Pinctada margaritifera) from the Central Pacific islands using three classes of molecular markers: two mitochondrial genes (mtDNA), five anonymous nuclear loci (anDNA), and eight polymorphic allozymes. Very low levels of haplotype diversity and nucleotidic divergence detected for mtDNA validate the hypothesis of a recent (re)colonization of Polynesian lagoons after their exondation during the last glaciations. Some nuclear loci, however, showed highly significant FST values, indicating a reduced amount of larval exchange between archipelagos at present.

Within-host parasite dynamics, emerging trade-off, and evolution of virulence with immune system.

Virulence is an evolutionary paradox because parasites never benefit from their host's death. The adaptive explanation of virulence is classically based upon the existence of physiological constraints that create a trade-off between parasites' epidemiological traits (virulence, transmissibility, and clearance). Here we develop an epidemiological model where infections are dynamic processes and we demonstrate how these dynamics generate a trade-off between emerging epidemiological parameters.

Identification and characterization of t haplotypes in wild mice populations using molecular markers.

As part of a population genetics survey of the hybrid zone between mouse subspecies Mus musculus domesticus and M. m. musculus, we identified and characterized the t haplotypes in 1068 mice from 186 different populations in a 2500 km2 area in central Jutland.

Putative involvement of crustacean hyperglycemic hormone isoforms in the neuroendocrine mediation of osmoregulation in the crayfish Astacus leptodactylus.

This study investigates the involvement of eyestalk neuroendocrine factors on osmoregulation in the crayfish Astacus leptodactylus maintained in freshwater. Eyestalk removal was followed by a significant decrease in hemolymph osmolality and Na(+) concentration and by a 50% increase in mass after one molting cycle. Several neurohormones have been isolated from the sinus gland through high-performance liquid chromatography (HPLC), and different crustacean hyperglycemic hormone (CHH)-related peptides, including stereoisomers (L-CHH and D-Phe(3) CHH), have been identified by direct enzyme-linked immunosorbent assay (ELISA).

[Natural hybridization between 2 sympatric species of mice, Mus musculus domesticus L. and Mus spretus Lataste].

Using protein loci and DNA markers, we show by a multilocus genetic analysis that certain populations of the two sympatric mouse species Mus musculus domesticus and Mus spretus show clear signs of partial introgression. Given the sterility of F1 males and the known partial genetic incompatibilities between the genomes of the two species, our finding does not invalidate the biological species complex, but allows to think that very limited genetic exchanges remain possible even long after the divergence of taxa. This may have some consequences on the dynamics of certain kinds of invasive or advantageous DNAs like transposable elements or pathogen resistance genes.

Is the Octomacridae the sister family of the Diplozodae?

Diplozoidae and Octomacridae are usually considered as sister families. Essentially this is because they are the only polyopisthocotyleans parasitising primary freshwater teleosts. Because of the lack of phylogenetically informative morphological characters to explore the pattern of colonisation of the primary continental freshwater teleosts and in order to understand the appearance of the "natural parabiosis" of Diplozoidae, a molecular phylogeny was inferred by comparing newly obtained partial 28S and 18S rDNA gene sequences of Eudiplozoon nipponicum and Diplozoon homoion with other already available sequences.

Genetic variability among cercariae of the Schistosomatidae (Trematoda: Digenea) causing swimmer's itch in Europe.

Ribosomal DNA sequences of the internal transcribed spacer 1 (ITS1) were obtained from schistosome cercariae responsible for swimmer's itch in Europe. Two types of ITS1 (1100 and 1400), which differ by the number of repeated patterns were found among cercariae shedded by Lymnaea ovata and L. auricularia (Lymnaeidae).

A Bayesian approach to the identification of panmictic populations and the assignment of individuals.

We present likelihood-based methods for assigning the individuals in a sample to source populations, on the basis of their genotypes at co-dominant marker loci. The source populations are assumed to be at Hardy-Weinberg and linkage equilibrium, but the allelic composition of these source populations and even the number of source populations represented in the sample are treated as uncertain. The parameter of interest is the partition of the set of sampled individuals, induced by the assignment of individuals to source populations.

[Molecular characterization of Diplozoidae populations on 5 species of Cyprinidae: new data on parasite specificity].

The genus Diplozoon (Platyhelminth) exhibits one of the most striking modes of reproduction. Adults reproduce after the permanent fusion of two larval hermaphrodites, which play a symmetrical role. The Diplozoidae are also exceptional among the Monogenea Polyopisthocotylea for two other reasons.

[Pseudorascora parva (Teleostei, Cyprinidae), an invasive species, a new vector for the maintenance and dissemination of anguillicolosis in France?]].

Pseudorasbora parva (Pisces, Cyprinidae) is an invasive species from eastern Asia. Known in France since 1983, it has only been observed since 1993 in the Rhône delta where large populations occur. 203 specimens of that fish species have been examined for L3-larvae of Anguillicola crassus.

Susceptibility of natural hybrids between house mouse subspecies to Sarcocystis muris.

A previous study showed that the susceptibility of hybrids between two Mus musculus musculus and Mus musculus domesticus did not apply to every parasite. The authors proposed that only parasites which exerted enough constraints would induce the selection of poorly compatible systems of resistance in the subspecies. This study completes the previous work.

Properties of bias and variance of two multiallelic estimators of F(ST).

This study compares theoretical and simulated properties of two estimators of fixation indices F(ST) for multiallelic data from a single locus. The estimators are due to Weir and Cockerham (straight theta(WC)) and to Robertson and Hill (;straight theta(RH)), respectively. Both estimators are linear combinations of biallelic estimators which differ in the way frequent and rare alleles are weighted.