Abstract:

Despite the species richness of the tilapiines, the fish have been compromised by various factors like overfishing, climate change and un-controlled fish translocations. These challenges particularly fish translocations have negatively impacted on native tilapiines through competition, hybridization and introgression thus compromising genetic integrity of the native tilapiines. Despite the prevailing research interventions, insufficient information is available on the hybridization levels of different tilapiines in the Lake Victoria basin. The study utilized nuclear microsatellite markers to investigate hybridization signals and compare the genetic diversity of different tilapiines in Lake Victoria, Kenya, based on next-generation sequencing. Tilapiines were collected from different beaches using experimental seine nets. A fin clip/muscle tissue was extracted from the fish sample, preserved in 98% ethanol, for subsequent genotyping in Meimberg laboratory at BOKU, Austria. The genetic structure based on Bayesian clustering analysis using STRUCTURE program and Principal Coordinate Analysis generally revealed two clusters: one group of O. niloticus and the other congeneric species. Despite this, some alleles of O. niloticus were observed in the genetic structure of other congeneric tilapiines. This suggested some degree of admixture/introgression among the studied tilapiines. With O. niloticus populations, there was a strong genetic differentiation between Dunga, Usenge, Mbita, Siungu and Seka-Bay (FST = 0.06, 0.05, 0.09 and 0.06 respectively). The differences could be attributed to geographical isolation that has acted as a barrier to gene flow between those populations. The apparent admixture of the different populations might be attributed to uncontrolled fish translocations and escapees from fish farms. Therefore, the current study contributes to identifying conservation measures of tilapiines that may be threatened and require management interventions.