top of page

What are the different kinds of samples that can be used for DNA analysis based genetic studies?

​

Biological samples can be broadly divided into two types, based on their mode of collection, for genetic studies on wildlife species. First, is invasive method, where physical capture and handling of an animal is required and second and the most preferred, is non-invasive method, where samples are collected without capture and handling of an animal. Following are some examples of various types of biological samples:

​

 1. Tissue Samples (Invasive)

  • Examples: Muscle, skin, liver, heart, kidney, or other organ tissues.

  • Uses: High-quality DNA, ideal for population genetics, genome sequencing, or forensic reference samples.

  • Source: Typically collected from carcasses, biopsies, or occasionally from live captures (e.g., fin clips in fish, ear punches in mammals).

2. Blood Samples (Minimally Invasive)

  • Examples: Whole blood, dried blood spots on filter paper.

  • Uses: Excellent DNA quality; used for individual identification, parentage testing, and disease/genetic diversity studies.

  • Source: Live captures, veterinary or conservation monitoring operations.

 3. Bone, Teeth, and Horn Material

  • Uses: Common for ancient DNA, forensic identification, and museum or confiscated specimens.

  • Challenges: DNA often degraded; requires specialized extraction protocols (e.g., silica-based or decalcification).

4. Feathers, Scales, or Hair

  • Uses: Non-invasive sources for species ID, population structure, and individual identification (if follicle/root present).

  • Quality: Variable — follicles yield more nuclear DNA, shafts mostly mitochondrial DNA.

5. Fecal Samples (Scat, dung, pellets, droppings)

  • Uses: Widely used in non-invasive genetic studies — species ID, sex determination, diet analysis, and population estimation using microsatellites or SNPs.

  • Challenges: DNA is often low-quality and mixed with environmental contaminants.

  • Applications: Carnivores, primates, herbivores — scat-based sampling avoids disturbing animals.

6. Shed Materials and Exuviae

  • Examples: Shed reptile skins, insect exuviae, molted fur.

  • Uses: Species ID, population genetics, and sometimes microbiome studies.

  • Advantages: Fully non-invasive and easy to collect.

7. Environmental DNA (eDNA)

  • Examples: DNA fragments present in water, soil, air, or sediments.

  • Uses: Detecting species presence/absence, biodiversity monitoring, early detection of invasive or elusive species.

  • Advantages: No need to directly observe or capture the organism.

  • Applications: Aquatic species monitoring, amphibians, mammals near water bodies, etc.

8. Saliva, Urine, or Other Bodily Fluids

  • Uses: Saliva (on prey remains or feeding sites) and urine (from snow or soil) can yield host DNA for individual ID or sexing.

  • Applications: Especially useful in carnivores and primates.

9. Museum and Archival Specimens

  • Examples: Dried skins, stuffed specimens, preserved tissues.

  • Uses: Historic DNA studies to examine temporal genetic changes, extinct species analysis.

  • Challenges: Highly degraded DNA — requires ancient DNA techniques.

bottom of page