Morin and Woodruff (1992) apparently were the first to use the term non-invasive with regard to genotyping material from unrestrained wildlife; however, widespread use of the term and application of the technique in field studies seemed to begin about 5 years later, spurred by their book chapter on the subject – Non-invasive genotyping for vertebrate conservation.
Non-invasive genetics is a modern technique for obtaining DNA for genotyping that is characterized by the indirect sampling of specimens, not requiring harm to, handling of, or even the presence of the organism of interest.
Non-invasive genetic sampling (NGS) is a relatively new data-collection approach with great potential for wildlife biologists.
By extracting genetic material from hair, faeces, or other DNA sources ( urine, feathers, shed skin, saliva, and egg shells to collect critical data), biologists are able to collect critical data about wildlife populations.
- In 1992,NGS was introduced as a method to obtain genetic samples from rare and elusive brown bears (Ursus arctos) in Europe (Höss et al. 1992, Taberlet and Bouvet 1992)
- To study social structure in chimpanzees(Pan troglodytes; Morin and Woodruff 1992).
Importance of non invasive genetics sampling
- To identify the presence of rare or elusive species,
- To monitor rare and sensitive species, where capture and handling are too risky, noninvasively-obtained samples provide a more acceptable method of study,
- To count & identify individuals, gender, diet items,
- To evaluate genetic diversity, population structure, and mating system.
- To estimate wildlife populations without handling, capturing, or even observing individual animals, examples,
- The majority of Tiger studies have relied on Conventional Techniques such as Surveys based on signs (e.g. pugmarks, scrapes, scat and urination patterns) Interviews with local inhabitants, Camera trapping
- Conventional techniques possess several disadvantages: Extended field time (~40-50 days), High cost of fieldwork
- Genetic monitoring has become a established scientific and convincing data-collection approach with great potential for wildlife and conservation biologists.
The three most essential applications of NGS for wildlife biologists: can be used in
- Species identification
2. Gender identification
3. Individual identification
Non-invasive sampling requires:
- Good Research design
- Require to have rigorous and systematic studies.
- Along with conventional/ traditional methods of gathering information
- To get a good sample size and intensity to estimate Population size and density.
- The two most commonly used sources of DNA for NGS studies are hair and fecal samples.
- Noninvasive genetic sampling studies have obtained genetic samples from a variety of sources. These samples contain mitochondrial DNA (mtDNA) and nuclear DNA (nDNA).
- Mitochondrial DNA is found in hundreds to thousands of copies per cell, while most cells have two copies of the nuclear DNA genome.
- Thus, DNA extractions from noninvasive genetic samples have more mtDNA than nDNA, and success rates are higher for mtDNA analyses.