Population expansion and genetic structure in Carcharhinus brevipinna in the southern Indo-Pacific.

ABSTRACT: BACKGROUND:Quantifying genetic diversity and metapopulation structure provides insights into the evolutionary history of a species and helps develop appropriate management strategies. We provide the first assessment of genetic structure in spinner sharks (Carcharhinus brevipinna), a large cosmopolitan carcharhinid, sampled from eastern and northern Australia and South Africa. METHODS AND FINDINGS:Sequencing of the mitochondrial DNA NADH dehydrogenase subunit 4 gene for 430 individuals revealed 37 haplotypes and moderately high haplotype diversity (h = 0.6770 ±0.025). While two metrics of genetic divergence (?ST and F ST) revealed somewhat different results, subdivision was detected between South Africa and all Australian locations (pairwise ?ST, range 0.02717-0.03508, p values ? 0.0013; pairwise F ST South Africa vs New South Wales = 0.04056, p = 0.0008). Evidence for fine-scale genetic structuring was also detected along Australia's east coast (pairwise ?ST = 0.01328, p < 0.015), and between south-eastern and northern locations (pairwise ?ST = 0.00669, p < 0.04). CONCLUSIONS:The Indian Ocean represents a robust barrier to contemporary gene flow in C. brevipinna between Australia and South Africa. Gene flow also appears restricted along a continuous continental margin in this species, with data tentatively suggesting the delineation of two management units within Australian waters. Further sampling, however, is required for a more robust evaluation of the latter finding. Evidence indicates that all sampled populations were shaped by a substantial demographic expansion event, with the resultant high genetic diversity being cause for optimism when considering conservation of this commercially-targeted species in the southern Indo-Pacific.

SUBMITTER: Geraghty PT 

PROVIDER: S-EPMC3783459 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature