Microsatellite markers and multiple paternity in the garter snake Thamnophis sirtalis

Data from four microsatellite loci developed for the common garter snake, T hamnophis sirtalis, show that multiple paternity is common in a natural pop ulation on Beaver Island, Michigan. Six of eight litters tested, and all li tters with five or more neonates, were multiply sired. At least triple pate rnity was documented in the largest litter examined (n = 13 neonates). Inhe ritance patterns and genotype frequencies in the wild population indicate t he presence of null allele(s) at one of the microsatellite loci. Garter sna kes are widely used in quantitative genetics research, and paternity testin g is essential in studies that rely on sibling analysis.