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¹ Biological Oceanography Division (BOD), National Institute of Oceanography (NIO), Dona Paula, Goa - 403004, India
² University of South Bohemia in České Budějovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Zátiší 728/II, 389 25 Vodňany, Czech Republic DOI : 10.4194/1303-2712-v14_2_25 Viewed : 4237 - Downloaded : 2962 Tunas of genus Auxis are commercially and ecologically important fish of family Scombridae. There is currently no information concerning the genetic divergence between A. thazard and A. rochei. Therefore, a study was conducted to estimate the degree of genetic divergence between two species based on PCR-RFLP analysis of D-loop region (500 bp) of mitochondrial DNA in 100 individuals collected from Tuticorin (India). High level of genetic divergence (9.26%) was observed between A. thazard and A. rochei. Estimates of molecular diversity indices were higher in A. rochei (π = 3.8808; hd = 0.9641) compared to A. thazard (π = 2.2514; hd = 0.8441). Based on demographic parameters, population expansion of A. thazard estimated to begin about 67,167 years before present while of founding of A. rochei took place about 114,747 years before present in Indian Ocean. Thus, we conclude that A. rochei represents the ancestral species of genus Auxis. Keywords : Tuna, Genetic variation, Conservation, Restriction sites, Haplotype