Development and characterization of microsatellite loci in the endangered catspaw, Epioblasma obliquata (Bivalvia: Unionidae)

The endangered Catspaw, Epioblasma obliquata, is restricted to one known reproducing population in Killbuck Creek, Coshocton County, Ohio. Little is known about the genetic diversity of this small population, and such information is needed to help inform recovery planning. We nonlethally sampled 44 individuals of E. obliquata using buccal swabs, from which we developed and characterized 14 polymorphic microsatellite loci. Significant deviations from Hardy–Weinberg Equilibrium (HWE), showing deficiencies in heterozygotes, were observed at 6 of the 14 loci, and linkage disequilibrium (LD) was observed at 9 (~10%) of 91 possible pairwise comparisons among loci. Allelic diversity ranged from 2 to 15 alleles per locus and averaged 7.6 alleles per locus. Observed heterozygosity per locus ranged from 0.091 to 1.000 and averaged 0.674. Possible explanations for deviations from HWE and LD could be from loci located close together on the same chromosome, segregation of null alleles, family structure within the small population, population bottlenecks, inbreeding, hermaphroditic reproduction, or some combination of these factors. Managers can use these microsatellite markers to assess and monitor genetic diversity in the remaining wild population in Killbuck Creek, prospective broodstock, hatchery-reared progeny, and reintroduced populations founded to promote recovery of the species.