PDF(Pubmed)
Abstract：
Cichlid fishes of the genus Oreochromis (tilapia) are among the most important fish for inland capture fisheries and global aquaculture. Deliberate introductions of non-native species for fisheries improvement and accidental escapees from farms have resulted in admixture with indigenous species. Such hybridization may be detrimental to native biodiversity, potentially leading to genomic homogenization of populations and the loss of important genetic material associated with local adaptation. By contrast, introgression may fuel diversification when combined with ecological opportunity, by supplying novel genetic combinations. To date, the role of introgression in the evolutionary history of tilapia has not been explored. Here we studied both ancient and recent hybridization in tilapia, using whole genome resequencing of 575 individuals from 23 species. We focused on Tanzania, a natural hotspot of tilapia diversity, and a country where hybridization between exotic and native species in the natural environment has been previously reported. We reconstruct the first genome-scale phylogeny of the genus and reveal prevalent ancient gene flow across the Oreochromis phylogeny. This has likely resulted in the hybrid speciation of one species, O. chungruruensis. We identify multiple cases of recent hybridization between native and introduced species in the wild, linked to the use of non-native species in both capture fisheries improvement and aquaculture. This has potential implications for both conservation of wild populations and the development of the global tilapia aquaculture industry.
摘要：
Oreochromis（罗非鱼）属的Cichid鱼类是内陆捕捞渔业和全球水产养殖中最重要的鱼类之一。故意引入非本地物种以改善渔业和意外逃离农场，导致与本地物种混合。这种杂交可能对本地生物多样性有害，可能导致群体的基因组均质化和与局部适应相关的重要遗传物质的损失。相比之下,当与生态机会相结合时，渗入可能会促进多样化，通过提供新的遗传组合。迄今为止,渗入在罗非鱼进化史中的作用尚未被探索。在这里，我们研究了罗非鱼的古代和最近的杂交，使用来自23个物种的575个个体的全基因组重测序。我们专注于坦桑尼亚，罗非鱼多样性的自然热点，以及以前曾报道过在自然环境中外来物种和本地物种之间杂交的国家。我们重建了该属的第一个基因组规模的系统发育，并揭示了整个Oreochromis系统发育中普遍存在的古代基因流。这可能导致了一种物种的杂交物种形成，O.Chungruensis.我们确定了多个最近在野外本地和引入物种之间杂交的病例，与非本地物种在捕捞渔业改善和水产养殖中的使用有关。这对野生种群的保护和全球罗非鱼水产养殖业的发展都有潜在的影响。
