Genetic Divergence of Philippine Tarsiers, Based on the 12S rRNA Gene, and its Implication for Their Taxonomic and Conservation Status

Abstract

The recent identification of distinct Philippine tarsier evolutionary lineages has raised concern over both the taxonomy and conservation status of the species across its geographical range. Its listing among the world’s most endangered primates from 2014–2016 further emphasized the need to address the previously unresolved issues regarding its taxonomy. However, the information needed for proper taxonomic resolution is still lacking. In this study, the genetic distances among the Philippine tarsier evolutionary lineages based on the mitochondrial 12S rRNA gene were estimated and compared with those of Eastern tarsier species from Sulawesi in order to build on the existing genetic information about them. Maximum likelihood (ML) analyses and Bayesian inference (BI) were used to infer phylogenetic trees from which groupings were recovered. Phylogenetic relationships were supplemented by a median-joining haplotype network analysis. Monophyletic tarsier clades were supported by the inferred trees. Groups corresponding to evolutionary lineages and species identified in the respective reference literature were recovered within both the Philippine tarsier and the Eastern tarsier clades. Among the Philippine tarsier groups, only the Dinagat-Caraga group was both strongly supported and monophyletic, whereas other groups exhibited a mixture of some samples among various haplotype clades. Pairwise genetic GTR+G distances among the Philippine tarsier groups ranged from 0.76–1.31%, and were found to be within the range or even higher than some of the genetic distances among Eastern tarsier species that ranged from 0.67–3.96%. Patterns among pairwise genetic distances suggest possible species-level distinction among the Philippine tarsier groups, with particular emphasis on the Dinagat-Caraga group and a possibility of crypsis within the Mindanao group, although further taxonomic input following an integrative approach is still needed. Recommendations for the priority research steps that are geared toward resolving taxonomic iss