CONSERVATION GENETICS OF THE WHITE-CLAWED CRAYFISH AUSTROPOTAMOBIUS-PALLIPES - THE USEFULNESS OF THE MITOCHONDRIAL-DNA MARKER

The white-clawed crayfish, Austropotamobius pallipes pallipes, still h as a wide-spread distribution in France, but since the last century, p opulations have declined because of habitat alteration (due to human d isturbance) and have been also eliminated by crayfish plague, for whic h introduced exotic species are a vector. Action plans for the conserv ation of A. pallipes are urgent and if recovery programmes are to be i nitiated 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 sho w how a new molecular marker can be used to study crayfish populations . Mitochondrial DNA (mtDNA) variation in natural populations was exami ned by restriction fragment length polymorphism analysis in samples ta ken from fifteen French populations and six European populations repre sentative of three subspecies observed in A. pallipes in order to exam ine the extent of differentiation between populations. Biogeographic c onsiderations about the genetic distances observed between the three s ubspecies 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 F rench populations exhibiting a high level of intrapopulational genetic variation are in fact mixed samples :the comparison with results obta ined in European populations revealed that the first population was co mposed of the two subspecies A. pallipes pallipes and A. pallipes ital icus and the second of A. pallipes italicus and A. pallipes lusitanicu s. 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 stock s between these basins. Consequently, mtDNA is an essential marker to measure genetic diversity between crayfish populations, to map how the subspecies are partitioned in France and what the importance of each is before any planning crayfish conservation strategies of the native crayfish.