Individualization of tiger by using microsatellites

In investigating criminal cases of poaching and smuggling involving tigers (Panthera tigris), the number of tiger individuals involved is critical for determining the penalty. Morphological methodologies do not often work because tiger parts do not possess the distinctive characteristics of the individual. Microsatellite DNAs have been proved a reliable marker for the individualization of animals. Seven microsatellite loci derived from domestic cat (Felis catus) were selected to individualize tigers, namely F41, F42, F146, Fca304, Fca391, Fca441 and Fca453. A reference population containing 37 unrelated tigers were used to investigate alleles, allelic frequencies, genotypes and genotype frequencies of each locus. Consequently, the data was used to assess the validity of the combination of seven loci for tiger individualization. All loci were polymorphic and easy to amplify. Three out of the seven loci were significantly departure from the Hardy-Weinberg Equilibrium (P < 0.05). Cumulative discrimination power (DP) calculated with observed genotype frequencies was 0.99999789. Match probability of an individual in the reference population with a random individual in seven loci ranged from 7.34 × 10−9 to 2.77 × 10−5. This suggests that combining the seven microsatellite loci provides desirable power to individualize tigers. The combination of seven loci was applied to a case of tiger bone smuggling. Genotypes of all samples were identical in all seven loci, and the PM of the evidence samples in the seven loci hit 5.63 × 10−7, provided evidence that the bones belong to a single tiger.