Phylogeography and population structure of the red stingray, Dasyatis akajei inferred by mitochondrial control region.

Abstract

The red stingray Dasyatis akajei is distributed in both marine and freshwater, but little is known about its phylogeography and population structure. We sampled 107 individuals from one freshwater region and 6 coastal localities within the distribution range of D. akajei. Analyses of the first hypervariable region of mitochondrial DNA control region of 474 bp revealed only 17 polymorphism sites that defined 28 haplotypes, with no unique haplotype for the freshwater population. A high level of haplotype diversity and low nucleotide diversity were observed in both marine (h = 0.9393 ± 0.0104, π = 0.0069 ± 0.0040) and freshwater populations (h = 0.8333 ± 0.2224, π = 0.0084 ± 0.0063). Significant level of genetic structure was detected between four marine populations (TZ, WZ, ND and ZZ) via both hierarchical molecular variance analysis (AMOVA) and pairwise FST (with two exceptions), which is unusual for elasmobranchs detected previously over such short geographical distance. However, limited sampling suggested that the freshwater population was not particularly distinct (p > 0.05), but additional samples would be needed to confirm it. Demersal and slow-moving characters likely have contributed to the genetically heterogeneous population structure. The demographic history of D. akajei examined by mismatch distribution analyses, neutrality tests and Bayesian skyline analyses suggested a sudden population expansion dating to upper Pleistocene. The information on genetic diversity and genetic structure will have implications for the management of fisheries and conservation efforts.