Genetic variability in the threatened crayfish Austropotamobius italicus: implications for its management.

We studied the genetic variability of the indigenous crayfish Austropotamobius italicus in 14 populations inhabiting five basins in Tuscany (Italy). This species is today subject to a drastic decline in the number and abundance of its populations across its entire range. Using a fragment of the mitochondrial DNA 16S rRNA gene, we identified eight haplotypes, six corresponding to A. i. italicus and two to A. i. meridionalis; the two clades were found in syntopy in one stream. Eight populations of A. i. italicus, analyzed for their microsatellite loci, showed a low intra-population genetic variability and a high inter-population genetic divergence. Populations sampled in the Sieve basin showed no heterozygotes and a high level of inbreeding. The knowledge on the genetic structure of the studied populations, combined with information on their ethology, ecology, and demography, is an essential prerequisite for any action aimed at reintroducing or restocking this threatened species.