The crustacean isopod Armadillidium vulgare is characterized by an unusual approximately 42-kb-long mitochondrial genome consisting of two molecules co-occurring in mitochondria: a circular approximately 28-kb dimer formed by two approximately 14-kb monomers fused in opposite polarities and a linear approximately 14-kb monomer. Here we determined the nucleotide sequence of the fundamental monomeric unit of A. vulgare mitochondrial genome, to gain new insight into its structure and evolution. Our results suggest that the junction zone between monomers of the dimer structure is located in or near the control region. Direct sequencing indicated that the nucleotide sequences of the different monomer units are virtually identical. This suggests that gene conversion and/or replication processes play an important role in shaping nucleotide sequence variation in this mitochondrial genome. The only heteroplasmic site we identified predicts an alloacceptor tRNA change from tRNA(Ala) to tRNA(Val). Therefore, in A. vulgare, tRNA(Ala) and tRNA(Val) are found at the same locus in different monomers, ensuring that both tRNAs are present in mitochondria. The presence of this heteroplasmic site in all sequenced individuals suggests that the polymorphism is selectively maintained, probably because of the necessity of both tRNAs for maintaining proper mitochondrial functions. Thus, our results provide empirical evidence for the tRNA gene recruitment model of tRNA evolution. Moreover, interspecific comparisons showed that the A. vulgare mitochondrial gene order is highly derived compared to the putative ancestral arthropod type. By contrast, an overall high conservation of mitochondrial gene order is observed within crustacean isopods.

The white-clawed crayfish, Austropotamobius pallipes pallipes, still has a wide-spread distribution in France, but since the last century, populations have declined because of habitat alteration (due to human disturbance) and have been also eliminated by crayfish plague, for which introduced exotic species are a vector. Action plans for the conservation of A. pallipes are urgent and if recovery programmes are to be initiated in France, then it is important to estimate how much genetic variation is partitioned between remaining populations as the species is being currently threatened in all its European distribution. We show how a new molecular marker can be used to study crayfish populations. Mitochondrial DNA (mtDNA) variation in natural populations was examined by restriction fragment length polymorphism analysis in samples taken from fifteen French populations and six European populations representative of three subspecies observed in A. pallipes in order to examine the extent of differentiation between populations. Biogeographic considerations about the genetic distances observed between the three subspecies are made. The study reveals a low level of genetic variation among English, Welsh and most of French populations, corresponding to a genetic stock uniformity among A. pallipes pallipes.The only two French populations exhibiting a high level of intrapopulational genetic variation are in fact mixed samples : the comparison with results obtained in European populations revealed that the first population was composed of the two subspecies A. pallipes pallipes and A. pallipes italicus and the second of A. pallipes italicus and A. pallipes lusitanicus.Results proved that some repopulations, performed in the past from A. pallipes italicus and supposed having failed, have been successful and that the French stock did not correspond to the only subspecies A. pallipes pallipes. A first analysis of genetic variance observed on a regional scale revealed that there was no genetic structure according to basins and could reflect human-mediated movement of crayfish stocks between these basins. Consequently, mtDNA is an essential marker to GÉNÉTIQUE ET CONSERVATION DE L'ÉCREVISSE À PATTES BLANCHES AUSTROPOTAMOBIUS PALLIPES : UTILITÉ DU MARQUEUR MITOCHONDRIAL.RÉSUMÉ L'écrevisse à pattes blanches Austropotamobius pallipes pallipes a encore une large répartition en France mais, depuis le siècle dernier, les populations ont été sérieusement réduites à cause de la dégradation des habitats suite à l'activité humaine et ont également été décimées par la peste de l'écrevisse, suite aux introductions d'espèces d'écrevisses exotiques. Si des actions de conservation d'A. pallipes sont urgentes à mettre en place, elles ne peuvent se faire sans une estimation préalable de la variabilité génétique des populations chez cette espèce actuellement en voie de disparition. La variabilité de l'ADN mitochondrial (ADNmt) dans les populations naturelles est examinée par polymorphisme de la longueur des fragments de restriction à partir...

In many species, males increase their reproductive success by choosing high‐quality females. In natural populations, they interact with both virgin and mated females, which can store sperm in their spermatheca. Therefore, males elaborate strategies to avoid sperm competition. In the terrestrial isopod Armadillidium vulgare, females can store sperm and produce several clutches. Moreover, this species can be parasitized by Wolbachia, which feminizes genetic males, transforming them into functional females. Our study compared attractiveness and mate choice when a male is exposed to both virgin and experienced females (i.e., females who have produced offspring and rested for 6 months), with or without Wolbachia. Our results revealed that males are more attracted to virgin females than experienced females, even if these virgin females are parasitized. Moreover, the chemical analysis highlighted different odors in females according to their reproductive and infection (Wolbachia‐free or vertically Wolbachia‐infected) status. Males attempted copulation more frequently and for longer with virgin females, even if Wolbachia‐infected, while experienced females refused further copulation. The evolutionary consequences of both male choice and female resistance on their fitness are discussed in this study.