Genetic variations and population structure in three populations of beardless barb, Cyclocheilichthys apogon (Valenciennes, 1842) inferred from mitochondrial cytochrome b sequences

Abstract This study aimed to investigate the relation of dispersal barrier and genetic diversity, population structure, and demographic history of 46 samples of beardless barb, Cyclocheilichthys apogon (Valenciennes, 1842) collected from three different locations in North-eastern Thailand. The analysis of molecular variance (AMOVA) was employed in order to determine the genetic variability within and among populations of this fish. The neutrality tests and mismatch distribution analysis were additionally applied to assess the neutrality and demographic expansion of the populations, respectively. Contiguous sequences within range from 1100 to1140 bp were obtained with varying 16 different haplotypes with high-haplotype diversity (0.8773 ± 0.0327) and low-nucleotide diversity (0.00215 ± 0.00020). The variations within and among populations accounted for 98.98 and 1.02% of the total variation, respectively. The low level of pairwise Fst estimations indicated a possible gene flow among populations and a suggestion of genetic homogeneity at this geographical range. A supportive idea of having a single-maternal lineage and past demographic expansion or selection experiencing has distinctly appeared among these populations. The current data suggests that all three populations distinctly exist as a single stock unit and that is an important factor in identifying genetic variation of C. apogon in this geographical area to be used in establishing effective plans and strategies for a conservation and management.