Which of the following statements accurately reflects the principle, application, and limitations of DNA barcoding in biodiversity assessment and species identification?
Show answer & explanation
Correct answer: B
Explanation
Solution: The correct answer is DNA barcoding relies on sequencing a short, standardized region of the genome—such as the COI gene in animals or rbcL/matK in plants—to identify and classify species, but its effectiveness may be limited by lack of reference databases and low resolution in closely related species.
Explanation:
☛ DNA barcoding is a molecular method that uses a short, standardized genetic region from a specific gene to identify species, rather than sequencing the entire genome.
☛ In animals, the standard barcode region is a 648-base-pair segment of the mitochondrial Cytochrome c oxidase subunit 1 (COI) gene.
☛ In plants, standard markers include chloroplast genes like rbcL and matK, because the mitochondrial genome evolves too slowly in plants.
☛ Limitations: This technique relies heavily on comparison with reference sequences in databases; therefore, a lack of comprehensive reference libraries or low genetic divergence among closely related species can reduce its accuracy.
Extra Exam-Relevant Facts:
☛ Father of DNA Barcoding: Canadian biologist Paul Hebert proposed this identification system in 2003.
☛ BOLD (Barcode of Life Data System): It serves as the primary international informatics platform and global reference database for DNA barcode records.
☛ Fungi Barcode: The primary universal DNA barcode marker for fungi is the ITS (Internal Transcribed Spacer) region.
☛ Applications: Widely used in identifying cryptic species, detecting food fraud (e.g., mislabeled seafood), combating illegal wildlife trafficking, and environmental DNA (eDNA) monitoring.
Important One-Liners for Upcoming Exams:
☛ Who is known as the "Father of DNA Barcoding"? → Paul Hebert
☛ Which mitochondrial gene is standardly used for animal DNA barcoding? → Cytochrome c oxidase subunit 1 (COI)
☛ Which two chloroplast genes are primary markers for plant barcoding? → rbcL and matK
☛ Which genetic region is designated as the universal barcode marker for fungi? → Internal Transcribed Spacer (ITS)
☛ What is the name of the central global database for storing DNA barcode records? → Barcode of Life Data System (BOLD)