First genomic resource for an endangered neotropical mega-herbivore: the complete mitochondrial genome of the forest-dweller (Baird’s) tapir (Tapirus bairdii)

Abstract

Baird’s tapir, or the Central American Tapir Tapirus bairdii (family Tapiridae), is one of the largest mammals native to the forests and wetlands of southern North America and Central America, and is categorized as ‘endangered’ on the 2014 IUCN Red List of Threatened Species. This study reports, for the first time, the complete mitochondrial genome of T. bairdii and examines the phylogenetic position of T. bairdii amongst closely related species in the same family and order to which it belongs using mitochondrial protein-coding genes (PCG’s). The circular, double-stranded, A-T rich mitochondrial genome of T. bairdii is 16,697 bp in length consisting of 13 protein-coding genes (PCG’s), two ribosomal RNA genes (rrnS (12s ribosomal RNA and rrnL (16s ribosomal RNA)), and 22 transfer RNA (tRNA) genes. A 33 bp long region was identified to be the origin of replication for the light strand (OL), and a 1,247 bp long control region (CR) contains the origin of replication for the heavy strand (OH). A majority of the PCG’s and tRNA genes are encoded on the positive, or heavy, strand. The gene order in T. baiirdi is identical to that of T. indicus and T. terrestris, the only two other species of extant tapirs with assembled mitochondrial genomes. An analysis of Ka/Ks ratios for all the PCG’s show values <1, suggesting that all these PCGs experience strong purifying selection. A maximum-likelihood phylogenetic analysis supports the monophyly of the genus Tapirus and the order Perissodactyla. The complete annotation and analysis of the mitochondrial genome of T. bairdii will contribute to a better understanding of the population genomic diversity and structure of this species, and it will assist in the conservation and protection of its dwindling populations.