Molecular Identification and Evolutionary Divergence of the Sri Lankan Sambar Deer, Rusa unicolor (Kerr 1792)

SIMPLE SUMMARY: Rusa unicolor (the Sambar deer) has been listed as a vulnerable species by the International Union for Conservation of Nature and Natural Resources (IUCN). These mammals play a significant role in the region’s biodiversity and are vital to the ecological system’s well-being. Because of their remarkable physical resemblances, differentiating between Sambar deer species can be challenging, often resulting in overlap across classifications. Hence, as a substitute for solely relying on morphological identification, a DNA barcode system can be employed as the best solution to address the challenges linked to their taxonomic classification. For the first time, our findings unveil that the Sri Lankan Sambar deer constitutes a distinct genetic subspecies. The outcome offers important molecular information, setting the foundation for future efforts in the conservation of these species. ABSTRACT: The Sambar is one of the largest deer species distributed mainly in Asia, and it has been listed as a vulnerable species. Taxonomy based on morphological characterization has been the gold standard method used to identify the Sambar deer species. Yet, morphological identification is challenging and requires expertise. To conduct species identification and taxonomic decisions, we performed the molecular identification of R. unicolor found in Sri Lanka using DNA barcodes, COI, and Cyt b to compare the Sri Lankan R. unicolor with the Indian R. unicolor and other R. unicolor subspecies. We obtained mitochondrial DNA sequences from COI and Cyt b from blood samples collected from the wet zone in Sri Lanka. A phylogenetic tree was constructed based on the Bayesian analyses using MrBayes 3.2.7. Molecular dating was implemented in Bayesian Evolutionary Analysis Sampling Trees (BEAST v1.8.2) on the concatenated sequence using a log-normal relaxed clock and Yule species tree prior, with four categories. The results showed that the Sri Lankan R. unicolor is genetically different from the Indian R. unicolor and other R. unicolor subspecies. The divergence occurred approximately 1.1 MYA (million years ago) in the Pleistocene era. The results are essential for designing new conservation platforms for these Sambar deer species.