DNA Barcoding for Species Identification: Current Applications and Future Perspectives

Abstract

Identification of biological species is an essential prerequisite for ecological monitoring, biodiversity conservation and global biosecurity efforts, and this requires an accurate and rapid process. This research paper gives an exhaustive empirical study on the effectiveness of DNA barcoding in the various taxonomic kingdoms, its present applications and future technological prospects. The main goal is to assess the usefulness of three sets of standardized genetic markers: mitochondrial cytochrome c oxidase subunit I (COI) gene for animals, rbcL and matK plastid regions for land plants and nuclear ribosomal internal transcribed spacer (ITS) region for fungi. This study highlights analytical assessment of two important parameters: amplification success plus species discrimination rates and determination of genetic divergence by barcode gap analysis. In terms of method, a vast number of specimens, ranging from marine fishes to terrestrial insects, medicinal plants and even phytopathogenic fungi were extracted for their DNA, amplified by polymerase chain reaction (PCR), and sequenced bidirectionally using high-throughput platforms. Subsequent bioinformatic analyses employed the Kimura 2-parameter (K2P) substitution model and the Neighbour-Joining algorithm. The results show that there is an outstanding species discrimination rate (over 98%) for animal taxa, and a significant barcode gap, with interspecific distance much larger than intraspecific. Using integrative multi-locus approaches, plant and fungal specimens showed variable but very reliable identification metrics. The future perspectives highlight the shift from single specimen analysis to environmental DNA (eDNA) metabarcoding, in concert with new technologies such as machine learning and next generation sequencing to rapidly drive the exponential growth in ecosystem-wide biomonitoring, forensic authentication and the mitigation of the global biodiversity crisis.

Introduction

This study examines the effectiveness of DNA barcoding as a standardized molecular tool for species identification across diverse taxonomic groups, including animals, plants, fungi, and birds. Accurate species identification is fundamental to biodiversity conservation, ecosystem management, evolutionary biology, and ecological research. Traditional species identification has relied on morphological and phenotypic characteristics, requiring extensive taxonomic expertise and large reference collections. However, conventional taxonomy often struggles to distinguish cryptic species, identify damaged or immature specimens, and resolve organisms with highly similar morphological features. DNA barcoding overcomes these limitations by using short, standardized genetic sequences to rapidly and accurately identify species.

The principle of DNA barcoding is based on the presence of a barcode gap, where genetic variation between different species is significantly greater than variation within members of the same species. In animals, a 650-base pair region of the mitochondrial cytochrome c oxidase I (COI) gene serves as the universal barcode because it evolves at an appropriate rate, lacks introns, and exists in high copy numbers within mitochondria. Since different kingdoms exhibit distinct evolutionary patterns, alternative barcode markers are required for other organisms. For plants, the rbcL and matK plastid genes form the core barcode, often supplemented by the ITS or trnH-psbA regions to improve species resolution. In fungi, the Internal Transcribed Spacer (ITS) region has been internationally recognized as the standard DNA barcode due to its broad applicability and high taxonomic resolution. The Barcode of Life Data System (BOLD) provides a global platform for storing, validating, and analyzing barcode sequences.

The growing biodiversity crisis caused by habitat destruction, climate change, pollution, and overexploitation has increased the importance of rapid and reliable species identification. Beyond taxonomy, DNA barcoding is widely applied in wildlife forensics, medicinal plant authentication, invasive species detection, agricultural pest management, conservation monitoring, and environmental assessment. More recently, advances in environmental DNA (eDNA) metabarcoding have enabled scientists to detect organisms through DNA naturally released into water, soil, or air, allowing comprehensive biodiversity monitoring without capturing organisms directly.

The literature survey demonstrates the broad success of DNA barcoding across multiple biological groups. In fisheries, studies have confirmed that the COI gene effectively identifies marine and freshwater fish species, reveals cryptic diversity, resolves taxonomic ambiguities, and supports conservation of threatened species such as sharks and deep-water fishes. Large-scale barcoding projects in India established verified reference libraries for commercially important fish species and confirmed the presence of a clear barcode gap between species.

In entomology, DNA barcoding has significantly accelerated insect identification, particularly among groups characterized by high morphological plasticity and sexual dimorphism. Studies of dragonflies and damselflies in the Western Ghats successfully reconstructed phylogenetic relationships using COI sequences and demonstrated the usefulness of molecular methods for biodiversity assessment and environmental monitoring. DNA barcoding has also improved identification of disease vectors and forensic insects, supporting epidemiological surveillance and public health management.

For plants, DNA barcoding has become an important tool for authenticating medicinal species and preventing adulteration in herbal products. The combination of rbcL, matK, and ITS2 markers has achieved high accuracy in distinguishing medicinal plants that cannot be reliably separated using morphology alone. In fungi, ITS-based barcoding has improved identification of economically important pathogens such as Fusarium, contributing to agricultural disease management and food security. The technology has also enabled non-invasive genetic monitoring of threatened wildlife through DNA extracted from naturally shed feathers, hair, or other biological materials, supporting conservation without disturbing living organisms.

The study employed a comprehensive and standardized molecular methodology involving sample collection from diverse ecosystems. Samples included marine and freshwater fishes, insects, medicinal plants, pathogenic fungi, and naturally shed feathers from the Indian peafowl (Pavo cristatus). Appropriate preservation techniques were used for each sample type to maintain DNA quality. Genomic DNA was extracted using optimized protocols tailored to different organism groups, followed by quality assessment using spectrophotometric analysis.

Species-specific DNA barcode regions were amplified through Polymerase Chain Reaction (PCR) using internationally accepted primer sets. COI primers were used for animals and insects, rbcL and matK primers for plants, and ITS1 and ITS4 primers for fungi. PCR products were verified through agarose gel electrophoresis and subsequently sequenced using high-throughput capillary sequencing technology. Sequence data underwent rigorous quality control, alignment, and comparison with reference databases including BOLD and NCBI GenBank. Genetic distances were calculated using the Kimura 2-Parameter (K2P) model, and phylogenetic relationships were reconstructed using Neighbour-Joining analysis supported by 1,000 bootstrap replicates.

The results demonstrate that DNA barcoding achieved consistently high success across all major taxonomic groups, although performance varied depending on the genetic marker and organism. Two key performance indicators were evaluated: amplification success rate and species discrimination rate.

Among animals, the mitochondrial COI gene showed outstanding performance. Marine fishes achieved an amplification success rate of 98.4% and a species discrimination rate of 99.1%, while freshwater fishes achieved 97.2% amplification and 98.5% species discrimination. Insects, including dragonflies and damselflies, showed 96.5% amplification success and 97.8% species discrimination, confirming COI as an exceptionally reliable barcode for animal identification and cryptic species detection.

Performance was lower for plants and fungi due to their more complex evolutionary histories. The combined rbcL + matK barcode achieved an amplification success rate of 88.3% but a lower species discrimination rate of 79.4% in medicinal plants. This reduced resolution reflects slow plastid genome evolution, hybridization, polyploidy, and incomplete lineage sorting among closely related plant species. Consequently, supplementary nuclear markers such as ITS2 remain necessary for accurate plant species identification. Fungal samples amplified successfully in 94.1% of cases using the ITS region and achieved an 86.2% species discrimination rate, although additional protein-coding genes may be required to distinguish closely related fungal pathogens.

The study also confirmed the existence of a well-defined barcode gap in animal taxa. Analysis of K2P genetic distances revealed a clear bimodal distribution separating low intraspecific genetic divergence (0–2%) from high interspecific divergence (10–25%). This distinct separation validates the theoretical foundation of DNA barcoding and demonstrates its ability to reliably distinguish species using standardized molecular markers.

Overall, the study concludes that DNA barcoding is a highly effective, reliable, and standardized approach for species identification across a wide range of organisms. The COI marker provides excellent resolution for animals, while rbcL, matK, and ITS effectively support plant and fungal identification when supplemented with additional markers where necessary. Combined with expanding reference databases and emerging technologies such as environmental DNA metabarcoding, DNA barcoding continues to play a vital role in biodiversity conservation, ecological monitoring, agriculture, wildlife forensics, and modern genomic research.

Conclusion

The overall molecular analysis of this study is very thorough and analytical, and leaves no doubts that DNA barcoding is indeed a very transformative, highly scalable and remarkably reliable molecular tool for accurate species identification and global biodiversity evaluation. The study compares systematic and mathematical success measures of critical amplification success, the exact species discrimination rate and highly detailed genetic divergence parameters in massively diverse taxonomic lineages, and concludes that internationally standardized marker loci, such as the mitochondrial COI gene for diverse animals, rbcL and matK from plastid in complex plants, and the highly actionable ITS region for fungi, are of incredible phylogenetic resolution and are highly useful. The exceptional and mathematically proven barcode gap consistently found across all taxa is of vital importance for unambiguous taxonomic identification, is invaluable for uncovering cryptic species and is an essential tool for ongoing surveillance of extremely sensitive and rapidly disappearing ecosystems. The inherent evolutionary challenges of plant and fungal taxa at the genome-level will occasionally compromise perfect species-level resolution, but the strict use of a highly integrative multi-locus molecular approach successfully and completely overcomes these biological difficulties. In the rapidly emerging genomic era, it will be possible to leverage the powerful integration of high-throughput environmental DNA (eDNA) metabarcoding, when used only in conjunction with cutting-edge bioinformatics, vast computing infrastructures powered by massive cloud storage, and sophisticated machine learning models, to exponentially increase our ability to continuously observe the changing global environment. Finally, the ongoing, global expansion and rigorously curated bioinformatic collections of reference library genes will enable modern scientists, wildlife conservationists and global policy makers to actively and aggressively fight the rapid, worldwide degradation of biodiversity with unprecedented molecular accuracy and ultimate scientific effectiveness.

References

[1] Akhilesh, K. V., White, W. T., Bineesh, K. K., & Pillai, N. G. K. (2013). Biological observations on the bristly catshark Bythaelurus hispidus from deep waters off the south-west coast of India. Journal of Fish Biology, 82(5), 1582-1595.21 [2] Bineesh, K. K., Gopalakrishnan, A., Akhilesh, K. V., Sajeela, K. A., Abdussamad, E. M., Pillai, N. G. K., Basheer, V. S., Jena, J. K., & Ward, R. D. (2016). DNA barcoding reveals species composition of sharks and rays in the Indian commercial fishery. Mitochondrial DNA Part A, 27(6), 4510-4517.18 [3] CBOL Plant Working Group. (2009). A DNA barcode for land plants. Proceedings of the National Academy of Sciences, 106(31), 12794–12797.9 [4] Dash, M., Tanasingh, N., Swain, S. K., Krishnan, K., Chowdhury, L., Pati, P. K., Prakash, B., Purohit, G. K., & Wani, M. A. (2026). Integrative characterization and DNA barcoding of Fusarium isolates from diverse agroecosystems. Indian Journal of Microbiology Research, 13(2), 193-200.23 [5] Ding, X., et al. (2025). Hidden in plain sight: discovery of sand flies in Singapore and description of four species new to science. Parasites & Vectors, 18(1), 402.17 [6] Hebert, P. D. N., Ratnasingham, S., & deWaard, J. R. (2003). Barcoding animal life: Cytochrome c oxidase subunit 1 divergences among closely related species. Proceedings of the Royal Society of London. Series B: Biological Sciences, 270(1512), 313–321.1 [7] Hollingsworth, P. M., Graham, S. W., & Little, D. P. (2011). Choosing and using a plant DNA barcode. PLoS ONE, 6(2), e19254.9 [8] Janzen, D. H., Hallwachs, W., Blandin, P., Burns, J. M., Cadiou, J. M., Chacon, I., ... & Hebert, P. D. N. (2009). Integration of DNA barcoding into an ongoing inventory of complex tropical biodiversity. Molecular Ecology Resources, 9(S1), 1-26.1 [9] Krishnan, J. E. K., & Sebastian, C. D. (2024). A molecular-based diversity assessment of Odonates through DNA barcoding. International Journal of Tropical Insect Science, 44(10), 1-10.22 [10] Kumar, A., Sinha, A., & Kanaujia, A. (2019). Using citizen science in assessing the distribution of Sarus Crane (Grus antigone antigone) in Uttar Pradesh, India. International Journal of Biodiversity and Conservation, 11(2), 58-68.15 [11] Lakra, W. S., Verma, M. S., Goswami, M., Lal, K. K., Mohindra, V., Punia, P., Gopalakrishnan, A., Singh, K. V., Ward, R. D., & Hebert, P. (2011). DNA barcoding Indian marine fishes. Molecular Ecology Resources, 11(1), 60–71.2 [12] Li, D.-Z., Gao, L.-M., Li, H.-T., Wang, H., Ge, X.-J., Liu, J.-Q., ... & Hollingsworth, P. M. (2011). Comparative analysis of a large dataset indicates that internal transcribed spacer (ITS) should be incorporated into the core barcode for seed plants. Proceedings of the National Academy of Sciences, 108(49), 19641-19646.9 [13] Pathak, M. R., Mohamed, A. A. M., & Farooq, M. (2018). DNA Barcoding and Identification of Medicinal Plants in the Kingdom of Bahrain. American Journal of Plant Sciences, 9(13), 2635-2651.11 [14] Ratnasingham, S., & Hebert, P. D. N. (2007). BOLD: The Barcode of Life Data System (http://www.barcodinglife.org). Molecular Ecology Notes, 7(3), 355–364.5 [15] Ratnasingham, S., & Hebert, P. D. N. (2013). A DNA-Based Registry for All Animal Species: The Barcode Index Number (BIN) System. PLoS ONE, 8(8), e66213.7 [16] Schoch, C. L., Seifert, K. A., Huhndorf, S., Robert, V., Spouge, J. L., Levesque, C. A., & Chen, W. (2012). Nuclear ribosomal internal transcribed spacer (ITS) region as a universal DNA barcode marker for Fungi. Proceedings of the National Academy of Sciences, 109(16), 6241–6246.12 [17] Trivedi, S., Rehman, H., Saggu, S., Panneerselvam, C., Abbas, Z. K., & Ansari, A. A. (2016). DNA Barcoding in Marine Perspectives. Springer International Publishing.26 [18] Tyabji, Z., Jabado, R. W., & Sutaria, D. (2018). New records of sharks (Elasmobranchii) from the Andaman and Nicobar Archipelago in India with notes on current checklists. Biodiversity Data Journal, 6, e28593.19 [19] Ward, R. D., Zemlak, T. S., Innes, B. H., Last, P. R., & Hebert, P. D. N. (2005). DNA barcoding Australia\'s fish species. Philosophical Transactions of the Royal Society B: Biological Sciences, 360(1462), 1847-1857.3 [20] Yogeshwari, M., & Varunprasath, K. (2020). Status and Distribution of Indian Peafowl (Pavo cristatus) in the South Coimbatore, Tamilnadu, India. Journal of Scientific Research and Reports, 26(1), 1-7.25

Copyright

Copyright © 2026 Ganesh H. Fadake, Swati R. Wadulkar, Vinay R. Zatale. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.