Genetic homogeneity in longtail tuna Thunnus tonggol (Bleeker, 1851) from the northwest coast of India inferred from direct sequencing analysis of the mitochondrial DNA D-loop region

Abstract

Longtail tuna Thunnus tonggol is a neritic species of the family Scombridae, having a confined coastal distribution to tropical and temperate waters of the Indo-Pacific region. In the present study, the population structure of longtail tuna was examined using sequence analysis of the mtDNA control region from two geographically distinct locations along the northwest coast of India. A 500 bp segment of the D-loop region was sequenced and analysed for 98 longtail tuna individuals. Analysis of population differentiation showed no significant genetic differentiation between the two sampling localities (Φ_ST = 0.005, P = 0.200). Results were further corroborated by a non-significant nearest-neighbour statistic (S_nn = 0.489, P = 0.549). Phylogeographic analysis revealed two haplogroups, but there was no obvious phylogeographic pattern separating the samples of the two localities. The present study suggests a single panmictic population of longtail tuna in the northwest coastal waters of India.

Key words:

• D-loop
• Indian waters
• longtail tuna
• mtDNA
• population structure

Acknowledgements

We take this opportunity to thank the Director, National Institute of Oceanography (NIO), Goa, India for providing the necessary facilities. The financial support for the project was provided by the Department of Science and Technology (DST), New Delhi, India to MRM by a grant-in-aid project ‘Genetic characterization of tunas using DNA markers’ and is gratefully acknowledged. SPK and GK are grateful to DST and NIO (Lizette D'Souza and V. Banakar) for their fellowship support. The authors also wish to thank N. Ramaiah for providing sequencing facilities. This paper forms a part of the PhD studies of SPK.

Editorial responsibility: Gavin Gouws