CHARACTERIZATION OF MICROSATELLITE DNA LOCI IN AMERICAN ALLIGATORS

Microsatellite loci of American alligators were identified from small insert DNA libraries. The average length of microsatellites (18.4 repe ats) was similar to that observed in mammals. Polymerase chain reactio n (PCR) primers were developed and tested for 20 microsatellite loci t hat contained at least 10 uninterrupted AC or AG repeats. Genotypes fo r the 15 loci that could be scored readily were obtained for alligator s from Louisiana and Florida. Eleven of the 15 loci were polymorphic. For the polymorphic loci, the number of alleles per locus ranged from 4-17 (average = 8.5), and observed heterozygosity within populations r anged from 0.231-0.865 (average = 0.466). Heterozygosity of these loci is almost 20 times higher than values obtained using isozymes. Popula tions from Louisiana and Florida differed substantially at these loci (overall F-ST = 0.137, theta(P) = 0.239, and R-ST = 0.387). The PCR pr imers also produced single amplicons from species of Alligatoridae, Ga vialidae, and Crocodilidae, indicating that they may be useful for gen etic studies in other crocodilians.