Quantitative evaluation of fecal drying methods for brown bear DNA analysis

DNA analysis of fecal samples is rapidly becoming an important tool in molecular ecology, conservation genetics, and wildlife management. Large-scale studies using fecal samples are rare due to difficulties associated with low DNA quality and quantity. To improve DNA amplification success of brown bear (Ursus arctos) DNA from fecal samples, we compared 4 drying methods: freeze-drying, oven drying, silica desiccant, and microwave drying. We assessed drying performance for 61 fecal samples by PCR amplification of 2 mitochondrial DNA (mtDNA) loci (150 bp, 700 bp) and a nuclear DNA (nDNA) microsatellite locus (200 bp). The method of drying affected mtDNA and nDNA amplification success rates. Freeze-drying and oven drying produced the greatest DNA amplification success rates. Success rates were high (oven-dried 95%, freeze-dried 98%) For mtDNA amplification required for species identification but relatively low (oven-dried 59%, freeze-dried 89%) for nDNA amplification required for individual identification from fecal samples.