DNA riboprinting analysis of Tilapia species and their hybrids using restriction fragment length polymorphisms of the small subunit ribosomal DNA

Morphometric, meristic and DNA riboprinting analyses of Tilapia species and their hybrids inhabiting the River Nile were examined. Morphometric data showed striking similarities and overlapping among Tilapia species, making it impossible to differentiate these species. Meristic characteristics revealed that Tilapia species could be identified into four major groups ( Oreochromis niloticus , O. aureus , Sarotherodon galilaeus and Tilapia zillii ). The lateral line scales differed significantly between the four Tilapia species, while the number of fin rays in the dorsal and anal fins differed significantly, differentiating three s pecies (but not between O. niloticus and O. aureus ). Restriction fragment length polymorphisms (RFLPs) of nuclear small sub‐unit ribosomal RNA (18S srRNA) gene were used to differentiate the species. Polymerase chain reaction‐restriction fragment length polymorphisms data provided a unique pattern for each species with a specific restriction enzyme. Two hybrids of Tilapia designated H 1 and H 2 were detected. The endonucleases Sac II and Apa I differentiated H 1 and H 2 . This research revealed a monophylogenetic relationship among all the studied Tilapia species.