Bavarian State Collection of Zoology, Münchhausenstrasse 21, Munich, Germany.
Proc Biol Sci. 2012 Nov 7;279(1746):4389-98. doi: 10.1098/rspb.2012.1667. Epub 2012 Sep 5.
The megadiverse haplochromine cichlid radiations of the East African lakes, famous examples of explosive speciation and adaptive radiation, are according to recent studies, introgressed by different riverine lineages. This study is based on the first comprehensive mitochondrial and nuclear DNA dataset from extensive sampling of riverine haplochromine cichlids. It includes species from the lower River Congo and Angolan (River Kwanza) drainages. Reconstruction of phylogenetic hypotheses revealed the paradox of clearly discordant phylogenetic signals. Closely related mtDNA haplotypes are distributed thousands of kilometres apart and across major African watersheds, whereas some neighbouring species carry drastically divergent mtDNA haplotypes. At shallow and deep phylogenetic layers, strong signals of hybridization are attributed to the complex Late Miocene/Early Pliocene palaeohistory of African rivers. Hybridization of multiple lineages across changing watersheds shaped each of the major haplochromine radiations in lakes Tanganyika, Victoria, Malawi and the Kalahari Palaeolakes, as well as a miniature species flock in the Congo basin (River Fwa). On the basis of our results, introgression occurred not only on a spatially restricted scale, but massively over almost the whole range of the haplochromine distribution. This provides an alternative view on the origin and exceptional high diversity of this enigmatic vertebrate group.
东非湖泊中的大型单型丽鱼辐射群是爆发性物种形成和适应性辐射的著名范例，根据最近的研究，它们是由不同的河流谱系渗入的。本研究基于对广泛采集的河流丽鱼进行的第一个综合线粒体和核 DNA 数据集。它包括来自刚果河下游和安哥拉（宽扎河）流域的物种。系统发育假说的重建揭示了明显不一致的系统发育信号的悖论。密切相关的 mtDNA 单型分布在数千公里之外，跨越了主要的非洲流域，而一些邻近的物种则携带明显不同的 mtDNA 单型。在浅层次和深层次的系统发育中，强烈的杂交信号归因于非洲河流复杂的晚中新世/早更新世古历史。多个谱系在不断变化的流域中的杂交塑造了每个主要的丽鱼辐射群，包括坦噶尼喀湖、维多利亚湖、马拉维湖和卡拉哈里古湖以及刚果盆地（福瓦河）的一个小型物种群。基于我们的结果，渗入不仅发生在空间上受限制的范围内，而且几乎发生在整个丽鱼分布范围内。这为这个神秘的脊椎动物群体的起源和异常高多样性提供了另一种观点。
