Genetic diversity and patterns of demographic expansion in natural populations of milkfish, Chanos chanos (Forsskål, 1775), in the Philippines

Abstract

The milkfish, Chanos chanos (Forsskål, 1775) is an important aquaculture species produced in the tropical Pacific region. Milkfish aquaculture is heavily reliant on seedstock; thus, there is a need to assess the genetic diversity of wild populations to identify areas that could be sources of high quality seedstock and broodstock. In this study, 631 milkfish specimens from 11 Philippine and, for comparison, two Indonesian wild populations were analysed for their genetic diversities using mitochondrial control region and cytochrome b. High genetic diversity indices were found for Sarangani, Claveria, and Camarines Sur populations in the Philippines. Philippine samples had either comparable or higher genetic diversity values than Indonesian samples from Medan and Sulawesi. Based on neutrality tests and mismatch distribution analysis, Philippine samples exhibited population expansion. Such pattern was not observed among Indonesian specimens. Genetic structure among populations was weak based on analysis of molecular variance (AMOVA). Correlation between genetic distance and geographic distance was not significant. Differentiation among marine biogeographic regions was small based on hierarchical AMOVA. High gene flow due to natural dispersal and influx of haplotypes brought about by importation may have contributed to the patterns observed, but diversification events within the Philippines were still evident.

Keywords:

• Aquaculture
• Chanos chanos
• genetic diversity
• milkfish
• mitochondrial DNA

Acknowledgements

We thank Dr. Maria Rowena R. Romana-Eguia, Dr. Ian Kendrich C. Fontanilla, and Dr. Maria Josefa R. Pante for helpful comments on this manuscript. We also thank Vonette F. Ballesteros-Padilla and John Carlos del Pozo for technical assistance. We are also grateful to Dr. Dalisay D. G. Fernandez, Engr. Eduardo V. Manalili, and Dr. Adelaida T. Calpe of DOST-PCAARRD for all the help.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was funded by the Department of Science and Technology-Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development (DOST-PCAARRD).