BACKGROUND The need for enhancing the productivity of fisheries in Africa triggered the introduction of non-native fish, causing dramatic changes to local species. In East Africa, the extensive translocation of Nile tilapia (Oreochromis niloticus) is one of the major factors in this respect. Using 40 microsatellite loci with SSR-GBS techniques, we amplified a total of 664 individuals to investigate the genetic structure of O. niloticus from East Africa in comparison to Ethiopian and Burkina Faso populations. RESULTS All three African regions were characterized by independent gene-pools, however, the Ethiopian population from Lake Tana was genetically more divergent (Fst = 2.1) than expected suggesting that it might be a different sub-species. In East Africa, the genetic structure was congruent with both geographical location and anthropogenic activities (Isolation By Distance for East Africa, R2 = 0.67 and Uganda, R2 = 0.24). O. niloticus from Lake Turkana (Kenya) was isolated, while in Uganda, despite populations being rather similar to each other, two main natural catchments were able to be defined. We show that these two groups contributed to the gene-pool of different non-native populations. Moreover, admixture and possible hybridization with other tilapiine species may have contributed to the genetic divergence found in some populations such as Lake Victoria. We detected other factors that might be affecting Nile tilapia genetic variation. For example, most of the populations have gone through a reduction in genetic diversity, which can be a consequence of bottleneck (G-W, < 0.5) caused by overfishing, genetic erosion due to fragmentation or founder effect resulting from stocking activities. CONCLUSIONS The anthropogenic activities particularly in the East African O. niloticus translocations, promoted artificial admixture among Nile Tilapia populations. Translocations may also have triggered hybridization with the native congenerics, which needs to be further studied. These events may contribute to outbreeding depression and hence compromising the sustainability of the species in the region.

中文翻译：

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东非自然和放养种群中尼罗罗非鱼（Oreochromis niloticus，L. 1758）的分子遗传多样性和分化。


背景技术提高非洲渔业生产力的需要引发了非本地鱼类的引入，导致当地物种发生巨大变化。在东非，尼罗罗非鱼（Oreochromis niloticus）的广泛易位是这方面的主要因素之一。我们利用 SSR-GBS 技术使用 40 个微卫星位点，扩增了总共 664 个个体，以研究东非尼罗罗非鱼与埃塞俄比亚和布基纳法索群体的遗传结构。结果 所有三个非洲地区都具有独立的基因库，然而，塔纳湖的埃塞俄比亚种群在遗传上比预期更加分歧（Fst = 2.1），这表明它可能是一个不同的亚种。在东非，遗传结构与地理位置和人类活动一致（东非距离隔离，R2 = 0.67，乌干达，R2 = 0.24）。来自图尔卡纳湖（肯尼亚）的尼罗罗非鱼被分离出来，而在乌干达，尽管种群彼此相当相似，但仍能够确定两个主要的自然流域。我们证明这两个群体对不同非本地人群的基因库做出了贡献。此外，与其他罗非鱼物种的混合和可能的杂交可能导致了维多利亚湖等一些种群中发现的遗传差异。我们检测到了可能影响尼罗罗非鱼遗传变异的其他因素。例如，大多数种群都经历了遗传多样性的减少，这可能是由于过度捕捞造成的瓶颈（GW，<0.5）、由于碎片化造成的遗传侵蚀或放养活动造成的创始人效应造成的。 结论 人类活动，特别是东非尼罗罗非鱼易位，促进了尼罗罗非鱼种群之间的人工混合。易位也可能引发了与天然同属物种的杂交，这需要进一步研究。这些事件可能会导致远交衰退，从而损害该地区物种的可持续性。