Background. Dawkinsia tambraparniei (Silas, 1954) is confined to an area not exceeding 100 km2 within a single watershed—the Tamiraparani River, southern Western Ghats, India. Its populations have recently declined, earning the fish the endangered status. For effective conservation efforts it is important to determine the levels of genetic variation between different populations. Therefore we attempted to quantify the cytochrome b (Cyt b) and cytochrome c oxidase subunit I (COI) gene sequence similarity between different populations of D. tambraparniei, as well as to study the phylogenetic relation with the closely related species D. arulius and D. filamentosa. Materials and methods. Samples were collected from 9 locations and 10 individuals from each were preserved for DNA analysis. The partial sequence of Cyt b and COI genes were amplified and sequenced. The sequences were aligned by the visual method using BioEdit version 7.1.3.0 and edited using Sequencer 4.7. The Bayesian consensus tree was constructed using the Monte Carlo Markov Chain (MCMC) method by BEAST v1.7.5. Results. The partial sequences of Cyt b and COI from 90 specimens of Dawkinsia tambraparniei representing nine populations were examined. The Cyt b gene sequences showed that all populations belong to a single haplotype and no nucleotide variation was observed between populations. In the case of COI gene sequences, two haplotypes were revealed: an additional haplotype with a clear transition of C to T at the nucleotide 58 position was detected within the Thalayanai Stream population. The phylogenetic analysis of COI gene demonstrated that the pair wise genetic distance between D. tambraparniei and D. arulius was low (0.004 ± SE 0.003) when compared with the distance between D. tambraparniei and D. filamentosa (0.061 ± SE 0.012). Conclusion. The mitochondrial DNA analysis revealed very low diversity among investigated populations of D. tambraparniei for studied genes, with the only local population from the Thalayanai Stream demonstrating certain divergence. The phylogenetic analysis confirms the concept on the validity of D. tambraparniei as a separate species. This phylogenetic study also demonstrated that D. tambraparniei is closer to D. arulius, followed by D. filamentosa.

endemic cyprinids, cytochrome b, cytochrome c oxidase I, phylogenetic tree