Development of microsatellite markers for the endangered freshwater pearl mussel Margaritifera margaritifera L. (Bivalvia: Unionoidea)

Freshwater pearl mussels ( Margaritifera margaritifera L.) are among the most critically endangered freshwater invertebrates. We describe the isolation and characterization of the first microsatellite markers for this species, which were obtained by screening 4900 recombinant clones from two genomic libraries. Thirteen loci revealed polymorphisms as demonstrated on 42 tested individuals from four river drainages. Allelic richness ranged from two to 12 alleles and averaged 6.8 alleles per locus with heterozygosity levels varying from 0 to 0.850 for observed heterozygosity ( H O ) and from 0.174 to 0.850 for expected heterozygosity ( H E ). Deficiency of heterozygous genotypes was observed in eight of 13 loci.