Do Habitat Features Modify Remarkable Genetic Homogeneity of Oreochromis niloticus Linnaeus, 1758 (Actinopterygii: Perciformes) Native to Burullus Lake, Rivulet and River Nile?

Abstract

The Cichlidae family, including the Nile tilapia (Oreochromis niloticus), is a key model for studying evolutionary genetic homogeneity. This study examined remarkable genetic homogeneity among tilapia populations in different Egyptian habitats; Burullus Bay, Shakhlouba watershed, a rivulet, and the River Nile using the ITS DNA region. Results showed 100% genetic similarity across populations, suggesting either frequent migration or a robust genetic structure enabling adaptation to diverse environments. However, future habitat fragmentation due to water shrinkage and salt intrusion may disrupt this genetic uniformity over time.Comparative BLAST analysis revealed high genetic similarity (93.77–100.00%) between Egyptian and Chinese O. niloticus isolates. For instance, an Egyptian isolate (On309) matched Chinese isolates at 99.87% (three samples) and 99.74% (six samples). Similarly, isolates from Burullus Bay (On80), the Damietta Nile branch (On77), and Shakhlouba watershed (On7785) showed 99.78% identity with multiple Chinese samples. The slightly lower pairwise identity (93.77%) for seven Chinese isolates may reflect habitat-specific influences. Notably, Shakhlouba’s polluted conditions—receiving wastewater from residential, agricultural, and religious sources—could contribute to minor genetic homogeneity.Overall, the study highlights the Nile tilapia’s genetic stability across varied habitats but warns that environmental changes may alter population structures. The high cross-regional genetic similarity suggests either recent common ancestry or strong adaptive capacity, though localized ecological factors may introduce subtle variations. These findings underscore the importance of monitoring habitat changes to predict long-term genetic impacts on this ecologically and economically vital species.