Hybridization between introduced and indigenous species can lead to loss of unique genetic resources and precipitate extinction. In Tanzania, the Nile tilapia (Oreochromis niloticus) and blue-spotted tilapia (Oreochromis leucostictus) have been widely introduced to non-native habitats for aquaculture and development of capture fisheries. Here, we aimed to quantify interspecific hybridization between these introduced species and the indigenous species Oreochromis esculentus, Oreochromis jipe and Oreochromis korogwe. In the Pangani basin, several hybrids were observed (O. niloticus × O. jipe, O. leucostictus × O. jipe, O. niloticus × O. korogwe), although hybrids were relatively uncommon within samples relative to purebreds. Hybrids between the native O. jipe × O. korogwe were also observed. In the Lake Victoria basin, no evidence of hybrids was found. Analysis of body shape using geometric morphometrics suggested that although purebreds could be discriminated from one another, hybrids could not be readily identified on body and head shape alone. These results provide the first evidence of hybridization between the introduced species and the Critically Endangered O. jipe in Tanzania. Given uncertainty regarding benefits of introduced species over large-bodied indigenous species in aquaculture and capture fisheries, we suggest that future introductions of hybridization-prone species should be carefully evaluated.

中文翻译：

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坦桑尼亚北部引进和极度濒危的本土罗非鱼鱼类之间的有限杂交

引进物种和本地物种之间的杂交会导致独特遗传资源的丧失并加速灭绝。在坦桑尼亚，尼罗罗非鱼 (Oreochromis niloticus) 和蓝斑罗非鱼 (Oreochromis leucostictus) 已被广泛引入非本地生境，用于水产养殖和发展捕捞渔业。在这里，我们旨在量化这些引入物种与本土物种 Oreochromis esculentus、Oreochromis jipe 和 Oreochromis korogwe 之间的种间杂交。在 Pangani 盆地，观察到了几种杂交种（O. niloticus × O. jipe、O. leucostictus × O. jipe、O. niloticus × O. korogwe），尽管相对于纯种，杂交种在样本中相对不常见。还观察到本地 O. jipe × O. korogwe 之间的杂交种。在维多利亚湖盆地，没有发现混血儿的证据。使用几何形态测量学对体型进行分析表明，虽然纯种可以相互区分，但单凭体型和头部形状无法轻易识别杂交种。这些结果提供了引入物种与坦桑尼亚极度濒危 O. jipe 之间杂交的第一个证据。鉴于在水产养殖和捕捞渔业中引入物种相对于大型本地物种的好处的不确定性，我们建议应仔细评估未来引入易于杂交的物种。这些结果提供了引入物种与坦桑尼亚极度濒危 O. jipe 之间杂交的第一个证据。鉴于在水产养殖和捕捞渔业中引入物种相对于大型本地物种的好处的不确定性，我们建议应仔细评估未来引入易于杂交的物种。这些结果提供了引入物种与坦桑尼亚极度濒危 O. jipe 之间杂交的第一个证据。鉴于在水产养殖和捕捞渔业中引入物种相对于大型本地物种的好处的不确定性，我们建议应仔细评估未来引入易于杂交的物种。