Genetic diversification, population structure, and geophylogeny of the Scarface rockskipper Istiblennius pox (Teleostei: Blenniidae) in the Persian Gulf and Oman Sea

Population structure, genetic diversity, and geophylogeny of five populations of the Scarface rockskipper, Istiblennius pox Springer & Williams, 1994 were explored from two ecoregions using the D-loop marker of the mitochondrial control region. The results revealed no significant population genetic structure and no provable recent demographic expansion in the studied samples. The phylogeographic pattern retrieved in this study was a deep genealogical separation with major lineages broadly sympatric. The possible reasons for this phylogeographic pattern could be explained by the following: (i) high gene flow in a species with large evolutionary effective population size, in which some anciently separated lineages might by chance have been retained, whereas many intermediate genotypes were lost over time by gradual lineage sorting; and (ii) secondary contact and admixture between allopatrically evolved populations/lineages as a result of the Late Pleistocene glaciations, followed by recent and ongoing colonization events and high level of gene flow along the coasts of the Persian Gulf and Oman Sea, caused by larval dispersal. These findings were incongruent with previous morphological studies on this species from the same area, suggesting that phenotypic variability among the Scarface rockskipper populations may arise without major genetic differentiation.