Which one of the following is most commonly used for barcoding-based identification of animal species?

Correct option is A

Cytochrome oxidase I (COI) gene is the most widely used marker in DNA barcoding for identifying animal species. This mitochondrial gene is highly conserved within species but shows enough variation between species to differentiate them. Due to its universality and ease of amplification, COI is considered the standard for animal species barcoding.

Explanation of the Other Options:

• Microsatellites: Although useful for genetic diversity studies and population analysis, microsatellites are not typically used in DNA barcoding because they are not as universally applicable across all species.
• 28S: The 28S ribosomal RNA gene is commonly used in phylogenetic studies but is not the standard for animal species barcoding.
• MatK: MatK is a chloroplast gene commonly used for plant species identification, not for animals.

Information Booster:

1. The COI gene is part of the mitochondrial genome and has been used extensively in the Barcoding of Life Database (BOLD).
2. DNA barcoding aims to identify species by comparing a short genetic sequence from a standard gene marker, such as COI.
3. The COI gene is widely used in animal species identification because of its high variation between species and its conservation within species.
4. The BOLD database has used COI to create a large reference library for identifying animal species globally.
5. Mitochondrial genes like COI are favored because they are inherited maternally and have high mutation rates, aiding in species differentiation.