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 di¡erentiate
these species. Meristic characteristics revealed that
Tilapia species could be identi¢ed into four major
groups (Oreochromis niloticus, O. aureus, Sarotherodon
galilaeus and Tilapia zillii). The lateral line scales differed
signi¢cantly between the four Tilapia species,
while the number of ¢n rays in the dorsal and anal
¢ns di¡ered signi¢cantly, di¡erentiating three species
(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 di¡erentiate the species. Polymerase
chain reaction-restriction fragment length polymorphisms
data provided a unique pattern for each
species with a speci¢c restriction enzyme. Two hybrids
of Tilapia designated H1 and H2 were detected.
The endonucleases SacII and ApaI di¡erentiated H1
and H2. This research revealed a monophylogenetic
relationship among all the studiedTilapia species. |
