Testing the reliability of noninvasive genetic sampling by comparing analyses of blood and fecal samples in Barbary...

Genetic studies of wild animal populations are often hindered by difficulties in obtaining blood samples. Recent advances in molecular biology have allowed the use of noninvasive samples as sources of DNA (e.g., hair or feces), but such samples may provide low-quality DNA and prevent the determination of true genotypes in subsequent DNA analysis. We present a preliminary study aimed at assessing the reliability of using fecal samples for genotyping in Barbary macaques (Macaca sylvanus). The test was performed on samples of blood and feces from 11 captive animals, using three dinucleotide microsatellites. The CTAB DNA extraction method was found to be the most relevant for Barbary macaque feces, yielding successful amplification at all loci for 70% of PCRs. All the fecal samples tested gave correct genotypes at least once for each locus when referenced against blood-derived genotypes. An average of 18.3% of PCRs displayed spurious genotypes (false homozygous or false allele). The minimum theoretical probability required to obtain a 100% accurate genotype is 0.74, based on the criterion that a correct genotype is assessed only if it was observed at least twice. The observed probability of obtaining a correct genotype from three PCRs, based on our genotyping results, was greater (0.81 on average) than the minimum threshold. In conclusion, our comparison of blood and fecal samples showed that fecal sampling is a reliable tool for the further study of wild Barbary macaque populations.