Reconstructing the evolution of baleen whales (Mysticeti) has been problematic because morphological and genetic analyses have produced different scenarios. This might be caused by genomic admixture that may have taken place among some rorquals. We present the genomes of six whales, including the blue whale (Balaenoptera musculus), to reconstruct a species tree of baleen whales and to identify phylogenetic conflicts. Evolutionary multilocus analyses of 34,192 genome fragments reveal a fast radiation of rorquals at 10.5 to 7.5 million years ago coinciding with oceanic circulation shifts. The evolutionarily enigmatic gray whale (Eschrichtius robustus) is placed among rorquals, and the blue whale genome shows a high degree of heterozygosity. The nearly equal frequency of conflicting gene trees suggests that speciation of rorqual evolution occurred under gene flow, which is best depicted by evolutionary networks. Especially in marine environments, sympatric speciation might be common; our results raise questions about how genetic divergence can be established.

中文翻译：

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蓝鲸和其他须鲸的全基因组测序发现了渐渗基因流的特征。

重建须鲸（Mysticeti）的进化一直存在问题，因为形态学和遗传分析产生了不同的场景。这可能是由一些狒狒中发生的基因组混合引起的。我们展示了包括蓝鲸（Balaenoptera musculus）在内的六种鲸鱼的基因组，以重建须鲸的物种树并识别系统发育冲突。对 34,192 个基因组片段的进化多位点分析揭示了 10.5 至 750 万年前，与海洋环流变化同时发生的短吻鳄的快速辐射。进化上神秘的灰鲸（EschrichtiusRobustus）属于须鲸类，蓝鲸基因组显示出高度的杂合性。冲突基因树的频率几乎相等，表明鹿类进化的物种形成是在基因流下发生的，这可以通过进化网络得到最好的描述。特别是在海洋环境中，同域物种形成可能很常见。我们的结果提出了如何确定遗传分化的问题。