Population genetic structure and demographic history of short mackerel, Rastrelliger brachysoma, in the Gulf of Thailand

Abstract

The short mackerel Rastrelliger brachysoma (Bleeker 1851) is an important fish in the Gulf of Thailand (GoT). The biology of this species has been intensively studied, but its genetic diversity is little known. The genetic diversity, population genetic structure, and demographic history of this species in the GoT were studied using complete mt control region sequences. The CR sequences of 455 mackerel samples collected from 23 localities at four fishing grounds revealed 333 haplotypes with haplotype diversity (h) per population, ranging between 0.8933 and 1.000, with an average of 0.9781. In turn, the nucleotide diversity (µ) ranged between 0.0119 ± 0.0060 and 0.0333 ± 0.0174, with an average of 0.0220 ± 0.00059.A haplotype network analysis showed that all sequences segregated into two subgroups named, clade I and clade II. Two clades were separated by 26 mutational steps. Each clade formed star-like clusters with many haplotypes derived from a common haplotype. Moreover, an analysis of molecular variance (AMOVA) revealed no significant differences among the studied localities, suggesting the presence of a single population in the GoT. Pairwise differences between samples from different fishing regions also indicated no population structure. Both Tajima’s D and Fu’s F_S statistics were highly significant for the two clades but nonsignificant for the entire population according to a mismatch distribution analysis. These results confirmed that both clades experienced demographic expansion. The estimated expansion times for clade I and clade II were 1,542.307 years (1.5423 ka BP) and 7,602.541 (7.6025 ka BP) years, respectively.

Keywords:

• Population genetics
• short mackerel
• Rastrelliger brachysoma
• the Gulf of Thailand
• stable mixing population

Acknowledgments

The authors are grateful to the Editor-in-Chief Dr. Antonio Baeza and Dr. Sergios-Orestis Kolokotronis, and two anonymous reviewers for their helpful suggestions and constructive comments. The authors are also grateful to Mr. N. Winfield for his help in reading the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was supported by a grant from the Kasetsart University Research Development Institute, Bangkok, Thailand.