Characterization of Microsatellite DNA Loci in American Alligators

Abstract

Microsatellite loci of American alligators were identified from small insert DNA libraries. The average length of microsatellites (18.4 repeats) was similar to that observed in mammals. Polymerase chain reaction (PCR) primers were developed and tested for 20 microsatellite loci that contained at least 10 uninterrupted AC or AG repeats. Genotypes for the 15 loci that could be scored readily were obtained for alligators 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 ranged from 0.231-0.865 (average = 0.466). Heterozygosity of these loci is almost 20 times higher than values obtained using isozymes. Populations from Louisiana and Florida differed substantially at these loci (overall FST = 0.137, O, = 0.239, and RST = 0.387). The PCR primers also produced single amplicons from species of Alligatoridae, Gavialidae, and Crocodilidae, indicating that they may be useful for genetic studies in other crocodilians.