First Analysis of Genetic Variability in Carinthian Populations of the White-Clawed Crayfish Austropotamobius Pallipes

Abstract

Several authors have speculated about the nativeness of the white-clawed crayfish (Austropotamobius pallipes) in the Austrian province of Carinthia, since this is the only occurrence of the species within the Danube river system. Phylogeographic analyses based on mitochondrial DNA sequences showed that Carinthian A. pallipes are closely related to specimens from Slovenia, Croatia and north-eastern Italy. These analyses additionally pointed to an absence of variability among populations in Carinthia. In the present study a larger number of individuals sampled from three different brooks in western Carinthia was investigated by analysing sequences of the mtDNA cytochrome c oxidase gene (COI), microsatellite DNA and microsatellite length variation in the nuclear ribosomal DNA internal transcribed spacer region (ITS1). Not only COI sequences revealed low degrees of genetic variability, but also microsatellite loci displayed low allelic diversity and low heterozygosity. Analysis of ITS1 microsatellite length variation in turn showed high levels of intragenomic variability, since single individuals manifested up to seven distinct fragments. Microsatellite data and ITS1 microsatellite length variation analyses also revealed significant differentiation among some population pairs. Since genetic divergence was mainly based on differences in allele frequencies and not on the occurrence of alternative alleles, we assume that Carinthian populations became isolated rather recently and that the occurrence of this species in this region is more likely to be a result of human introduction than of natural postglacial colonisation. PREMIÈRE ANALYSE DE LA VARIABILITÉ GÉNÉTIQUE DES POPULATIONS D'ÉCREVISSE À PATTES BLANCHES AUSTROPOTAMOBIUS PALLIPES EN CARINTHIE RÉSUMÉPlusieurs auteurs ont spéculé sur l'origine de l'écrevisse à pattes blanches (Austropotamobius pallipes) de la province autrichienne de Carinthie, parce que c'est la seule référence à la présence de l'espèce dans le bassin du Danube. Les analyses phylogéographiques basées sur des séquences de l'ADN mitochondrial montrent que A. pallipes de Carinthie est étroitement liée aux spécimens de Slovénie, Croatie et du nord-est de l'Italie. De plus, ces analyses mettent en évidence l'absence de variabilité au sein de populations de Carinthie. Dans la présente étude un plus grand nombre d'individus prélevés dans trois ruisseaux différents de l'ouest de la Carinthie a été étudié par analyse des séquences du gène mitochondrial cytochrome c oxidase (COI), d'ADN microsatellite et des variations de la longueur des microsatellites au niveau des régions intergéniques transcrites (ITS1) internes des ribosomes nucléaires. Non seulement les séquences du COI révèlent des faibles niveaux de variabilité génétique, mais également les loci microsatellites montrent une faible diversité allélique ainsi qu'une faible hétérozygotie. Par contre les analyses des variations des longueurs des microsatellites ITS1 ont montré des hauts niveaux de variabilité intragénomique, puisque jusqu'à sept...

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