Searching for common threads in threadfins: phylogeography of Australian Polynemids in space and time

Proper management of marine fisheries requires an understanding of the spatial and temporal dynamics of marine populations, which can be obtained from genetic data. While numerous fisheries species have been surveyed for spatial genetic patterns, temporally sampled genetic data is not available for many species. Here we present a phylogeographic survey of the king threadfin, Polydactylus macrochir, across its species range in northern Australia and at a temporal scale of one and ten years. Spatially the overall AMOVA fixation index was Φst = 0.306 (F’st = 0.838), p < 0.0001 and isolation by distance was strong and significant (r2 = 0.45, p < 0.001). Temporally, genetic patterns were stable at a time scale of ten years. However, this did not hold true for samples from the eastern Gulf of Carpentaria, where populations showed a greater degree of temporal instability and lacked spatial genetic structure. Temporal but not spatial genetic structure in the Gulf indicates demographic int...