Factors affecting the amount of genomic DNA extracted from ape faeces and the identification of an improved sample storage method

Genetic analysis using noninvasively collected samples such as faeces continues to pose a formidable challenge because of unpredictable variation in the extent to which usable DNA is obtained. We investigated the influence of multiple variables on the quantity of DNA extracted from faecal samples from wild mountain gorillas and chimpanzees. There was a small negative correlation between temperature at time of collection and the amount of DNA obtained. Storage of samples either in RNAlater solution or dried using silica gel beads produced similar results, but significantly higher amounts of DNA were obtained using a novel protocol that combines a short period of storage in ethanol with subsequent desiccation using silica.