Empirical evaluation of preservation methods for faecal DNA

Area of Science:

• Molecular Ecology
• Wildlife Biology
• Conservation Genetics

Background:

• Faecal DNA analysis is vital for non-invasive wildlife monitoring.
• DNA in faecal samples is often degraded, posing challenges for genetic analysis.
• Optimizing sample preservation is key to successful DNA extraction and genotyping.

Purpose of the Study:

• To compare the effectiveness of four preservation methods for faecal DNA.
• To determine the best methods for preserving nuclear and mitochondrial DNA from baboon faeces.
• To provide recommendations for sample collection in molecular scatology studies.

Main Methods:

• Faecal samples from free-ranging baboons were collected.
• Four preservation methods were tested: DMSO/EDTA/Tris/salt solution (DETs), 70% ethanol, freezing (-20°C), and drying.
• DNA was extracted, and PCR assays were performed to assess amplification success for different DNA types and fragment lengths.

Main Results:

• Amplification success varied significantly based on preservation method, PCR product size, and DNA type (nuclear vs. mitochondrial).
• DETs solution was superior for preserving nuclear DNA.
• Ethanol, freezing, and drying showed similar effectiveness for mitochondrial DNA and short nuclear DNA fragments (< 200 bp).

Conclusions:

• The optimal faecal sample preservation method depends on the target DNA and fragment size.
• For degraded faecal DNA, using short nuclear markers and potentially repeating extractions is recommended.
• Collecting 3-6 faeces per individual is advised for robust molecular scatology studies.