Gene flow and genetic structure in Nile perch, Lates niloticus, from African freshwater rivers and lakes

Abstract

BackgroundGeological evolution of the African continent has been subject to complex processes including uplift, volcanism, desert formation and tectonic rifting. This complex geology has created substantial biogeographical barriers, and coupled with anthropogenic introductions of freshwater fishes, has influenced the genetic diversity, connectivity and sub-structuring of the teleost fauna. Nile perch, Lates niloticus, is an iconic fish in Africa and is of high commercial importance, both in the species’ native range and where it has been translocated. However, the species is in decline and there is a need to understand its population genetic structure to facilitate sustainable management of the fishery and aquaculture development.MethodologyNile perch tissue samples were acquired from two West and four East (Lakes; Albert, Kyoga, Victoria and Turkana) African locations. Nineteen polymorphic microsatellite loci were used to study the genetic variation among populations across regions (West and East Africa), as well as between native and introduced environments within East Africa.Principal findings and their significanceResults revealed strong and significant genetic structuring among populations across the sampled distribution (divergence across regions, FCT = 0.26, P = 0.000). STRUCTURE analysis at a broad scale revealed K = 2 clusters, the West African individuals were assigned to one cluster, while all individuals from the East African region, regardless of whether native or introduced, were assigned to another cluster. The distinct genetic clusters identified in the current study between the West and East African Nile perch, appear to have been maintained by presence of biogeographic barriers and restricted gene flow between the two regions. Therefore, any translocations of Nile perch should be carefully considered across the regions of West and East Africa. Further analysis at a regional scale revealed further structuring of up to K = 3 genetic clusters in East African Nile perch. Significantly (P < 0.05) lower genetic diversity based on analysis of allelic richness (AR) was obtained for the two translocated populations of Lake Kyoga (AR = 3.61) and Lake Victoria (AR = 3.52), compared to Nile perch populations from their putative origins of Lakes Albert (AR = 4.12) and Turkana (AR = 4.43). The lower genetic diversity in the translocated populations may be an indication of previous bottlenecks and may also indicate a difficulty for these populations to persist and adapt to climatic changes and anthropogenic pressures that are currently present in the East African region.

Population Structure and Genetic Diversity of Nile Tilapia (Oreochromis niloticus) Strains Cultured in Tanzania

“…Forming a base population containing high genetic diversity will be crucial for the success of any future breeding program in Tanzania (Fernández et al, 2014;García-Ballesteros et al, 2017). Furthermore, introductions of fish from one region to another have affected the genetic diversity and population structure of many teleost fish species (Basiita et al, 2018). Due to mismanagement and uncontrolled movement of fish from different regions there is limited information relating to the genetic structure of Nile tilapia strains and their distribution in Tanzania.…”

Development and Sensory Evaluation of Omega-3-Rich Nile Perch Fish Oil-Fortified Yogurt

“…Fish and other seafood are rich sources of omega-3 fatty acids. Nile perch is a warm water fish present in East African lakes and rivers, and its processing results in by-products such as fat pads that remain underexploited [ 26 ]. Local women purchase the fat pads and use them to deep fry fish since they are cheaper compared to other commercial fats and oils.…”

Using the novel priority index in prioritizing the selection of inland water bodies for site-based fish species conservation

“…The falls along River Semiliki prevents fish passage to Lake Albert from Edward (Acere & MweneBeyanga 1990). Similarly, between Lake Victoria and Kyoga have been separated by the Owen and Bujagali falls (Basiita et al 2018), and a sandbar between Lake Nabugabo and Victoria (Stager et al 2005). These biogeographical barriers may have led to allopatric speciation; for instance, Lake Nabugabo which was once connected to Lake Victoria had five endemic species (Ogutu-Ohwayo 1993; van Alphen et al 2004).…”