Abstract:
The introduction of invasive Nile tilapia (Ore-
ochromis niloticus), and the rapacious predator Nile perch
(Lates niloticus), into Lake Victoria resulted in a decline in
population sizes, genetic diversity and even extirpation of
native species which were previously the mainstay of local
fisheries. However, remnant populations of native fish
species, including tilapia, still persist in satellite lakes
around Lake Victoria where they may coexist with O.
niloticus. In this study we assessed population genetic
structure, diversity, and integrity of the native critically
endangered Singidia tilapia (O. esculentus) in its refugial
populations in the Yala swamp, Kenya, and contrasted this
diversity with populations of the invasive tilapia O. nil-
oticus in satellite lakes (Kanyaboli, Namboyo and Sare)
and Lake Victoria. Based on mtDNA control region
sequences and eight nuclear microsatellite loci, we did not
detect any mtDNA introgression between the native and
the invasive species in Lakes Kanyaboli and Namboyo, but
did find low levels of nuclear admixture, primarily from O.
niloticus to O. esculentus. Some genetic signal of O. es-
culentus in O. niloticus was found in Lake Sare, where O.
esculentus is not found, suggesting it has recently been
