Plucked hair samples as a source of DNA: reliability of dinucleotide microsatellite genotyping

To test whether plucked hairs are a reliable source of DNA for genotyping microsatellite loci, we carried out experiments using one, three, or 10 hairs per extract for 50 alpine marmots. For each extract, seven independent genotypings were performed for the same locus (multiple-tubes approach). Two types of genotyping errors were recorded: a false homozygote defined as the detection of only one allele of a true heterozygote, and a false allele defined as a PCR-generated allele that was not one of the alleles of the true genotype. Using DNA extracted from one, three, or 10 hairs the overall error rate was 14.00%, 4.86%, and 0.29%, respectively. Based on our results, we conclude that 10 hairs should be used to obtain consistently reliable genotypings using the single-tube approach, and that a single plucked hair could represent a reliable source of DNA if the multiple-tubes approach is used. For future studies of dinucleotide repeat diversity using DNA extracted from one to three shed or plucked hairs, we strongly recommend initiating an appropriate pilot study to quantify the error rate and to determine the reliability of the single-tube approach.