Role of Mitochondrial DNA in Vertebrate Biodiversity Research: Its Structure, History, Existence, and Relevance in the Age of Next‐Generation Sequencing and Genomics

A comprehensive review of vertebrate mitochondrial DNA (mtDNA), including its molecular diversity and applications, is lacking. By comparing mtDNA structures from fish to mammals, this review provides a comprehensive account of the structural variations in vertebrate mtDNA in terms of its control region, structural heterogeneity, spacer sequences, sequence overlaps, and gene rearrangements. It discusses the inheritance, mutation mechanisms, and utilization of mtDNA markers, particularly cyt b and COI genes, in evolution and ecology, focusing on molecular barcoding. Moreover, focusing on technological advancements in next‐generation sequencing (NGS) and its revolutionary role in molecular biodiversity, ecological interrelations, and species extinction, we summarize different NGS‐based methods, namely minibarcode and SNP genotyping. eDNA metabarcoding further validated the capability of the COI marker as a minibarcode for fast and efficient biodiversity assessment. In this context, we discuss the relevance of mega‐biodiversity initiatives such as the Earth Biogenome Project and International Barcode of Life. The use of mtDNA in barcoding caters to intact specimens and scattered DNA fragments. This is a broad review of mtDNA structure and the role of a regulatory region, in addition to the functional biodiversity of the species.