García G, Gutiérrez V, Ríos N, Turner B, Santiñaque F, López-Carro B, Folle G
Sección Genética Evolutiva, Facultad de Ciencias, UdelaR, Iguá 4225, CP 11400, Montevideo, Uruguay,
Genetica. 2014 Feb;142(1):87-98. doi: 10.1007/s10709-014-9756-7. Epub 2014 Jan 23.
The extent to which genome sizes and other nucleotypic factors influence the phyletic diversification of lineages has long been discussed but remains largely unresolved. In the present work, we present evidence that the genomes of at least 16 species of the neotropical rivulid killifish genus Austrolebias are unusually large, with an average DNA content of about 5.95 ± 0.45 picograms per diploid cell (mean C-value of about 2.98 pg). They are thus larger than the genomes of very nearly all other diploid, i.e. non-(paleo) polyploid species of actinopterygian fishes so far reported. Austrolebias species appear to be conventional diploids in all other respects and there is no reason to believe that they arise from polyploid ancestors. The genome sizes reported for other rivulid killifishes, including a putative sister group, are considerably smaller and fall within the range typical of most other cyprinodontoid species. Therefore, it appears that the ancestor(s) of contemporary Austrolebias have undergone one or more episodes of genome expansion encompassing sudden speciation process during the Pleistocene. In addition, these findings are consistent with the hypothesis of a positive correlation between species richness and genome size.
基因组大小和其他核型因素在多大程度上影响谱系的系统发育多样化，长期以来一直是讨论的话题，但在很大程度上仍未得到解决。在本研究中，我们提供证据表明，新热带区溪鳉属Austrolebias的至少16个物种的基因组异常大，每个二倍体细胞的平均DNA含量约为5.95±0.45皮克（平均C值约为2.98皮克）。因此，它们比迄今为止报道的几乎所有其他二倍体（即非（古）多倍体）辐鳍鱼类的基因组都要大。Austrolebias物种在所有其他方面似乎都是传统的二倍体，没有理由相信它们起源于多倍体祖先。报道的其他溪鳉科鱼类的基因组大小，包括一个假定的姐妹群，要小得多，并且落在大多数其他鲤齿类物种的典型范围内。因此，当代Austrolebias的祖先似乎经历了一次或多次基因组扩张事件，包括更新世期间的突然物种形成过程。此外，这些发现与物种丰富度和基因组大小之间呈正相关的假设一致。
