Morphometric, meristic and DNA ripoprinting analyses of Tilapia species and their hybrids inhabiting the River Nile were examined. The obtained morphometric data evoke striking similarities and overlapping among tilapia species. Accordingly it could not able to differentiate tilapia species. The obtained data of meristic characters reveal that tilapia species could be differentiated into four species {Oreochromis niloticus, O. auraeus, Sarotherodon galilaeus and Tilapia zillii). The lateral line scales differed significantly among the four-studied tilapia species. While the number of fin rays in the- dorsal and anal fins differentiate significantly three Tilapia species (Confusion between 0. niloticus and 0. auraeus). Furthermore, the study used the technique of restriction fragment length polymorphism (RFLP) of nuclear small sub-unit ribosomal RNA (18SsrRNA ) gene. The PCR-RFLP data provide a unique pattern for each examined species with a specific restriction enzyme. So, it could be possible to detect two hybrids of tilapia fish which are given HI and H2 symbols. The endonucleases Sacll and Apal differentiate HI and H2, respectively. Furthermore, the analyses of PCR-RFLP data indicate that the HI are closer to O. niloticus and S. galilaeus, whereas the H2 is phylogenetically closer to O. auraeus and T. zillii. The data of this research evoke a monophyiogenetic relationship of all the studied Tilapia species. |
