International Journal of Aquaculture, 2025, Vol.15, No.1, 21-28 http://www.aquapublisher.com/index.php/ija 24 aquaculture efficiency (Nayfa et al., 2020). The universality and influence of this structural variation reveals the important role of genomic structural variation in the domestication of tilapia. Figure 1 Representatives of Nile tilapia populations from EA illustrating digitized landmarks used in geometric morphometrics (Adopted from Mwanja et al., 2010) Image caption: A = Albert, E = Edward, G = George, KC=Kazinga Channel, RN = River Nile, T = Turkana, Ky = Kyoga, VK=Victoria Kakyanga, M = Mulehe, Ka = Kayumbu, Rf = Rwitabingi farm, Sf = Sindi farm and Bf = Bagena farm (Adopted from Mwanja et al., 2010) 4.3 Traces of domestication of genes related to important economic traits Economic trait genes leave clear traces during the domestication of tilapia. These genes are often closely related to growth rate, meat quality, reproductive performance, and environmental tolerance. Some tilapia species are good candidates for saltwater and seawater farming because they can grow at high salinity. In the article "Status of conventional and molecular breeding of salinity-tolerant tilapia", Mozambique tilapia, golden tilapia, maolipapia, uropia, galipapia and zili tilapia are the most salt-resistant (Yue et al., 2023). Hybrids from salt-tolerant tilapia species can tolerate a certain degree of salinity. They have been used in aquaculture production in saltwater and all seawater. Conventional breeding has been applied to improve the growth rate of salt-resistant tilapia. However, they grow at a lower rate than freshwater Oreochromis niloticus. Recently, many genomic resources and tools have been developed for salt-resistant tilapia. Quantitative trait loci (QTL) mapping and genome-wide association studies (GWAS) for important economic traits have been applied in molecular breeding of excellent salt-tolerant tilapia lines. 5 Cross-Regional Introduction and Genetic Drift of Tilapia 5.1 Genetic drift phenomenon in the process of transcontinental introduction of tilapia Since its introduction to Africa and its growth, tilapia has experienced many complex transmission paths. This long-distance migration and breeding process is inevitably accompanied by genetic drift phenomenon. Taking the introduction of tilapia from Africa to Asia as an example, the initial introduction was limited, and many of the originally abundant genotypes gradually decreased or even disappeared when these fish were breeding in new environments. At the same time, some of the rarer genes may increase due to accidental events. In the 1950s, Taiwan introduced tilapia from Africa. After decades of breeding, the rare genotypes in some primitive African populations have become mainstream among Asian breeding populations (Yustiati et al., 2020). This random
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