美国旧金山州立大学生物学助理教授卡伦-克劳表示：“我们的研究发现匙吻鲟拥有自身基因组的副本。这种复制形成了额外的基因材料，提高了比较研究的复杂性。这可能改变我们针对肢体发育的研究方式。”为了研究人类的肢体如何发育，科学家将老鼠的肢体基因与鱼类的鳍基因进行比较。此前有关匙吻鲟的研究显示，这种鱼类在出现四足动物前很久就拥有生长出肢体所需要的“基因包”。四足动物最后进化成爬行类、鸟类、两栖类和哺乳动物。
研究中，克劳和同事对美洲匙吻鲟含有19个Hox基因的染色体片段进行了排序。Hox基因决定体形和肢体发育，同时也是帮助科学发现整个基因族副本的主要指示器。完整基因组副本被研究人员称之为进化史上“一个颠覆游戏规则的事件”，让一种物种出现新种或者奇特种群创造了条件。
这种复制的出现是一系列看似不可能的条件同时满足的结果，让匙吻鲟的每一个基因都拥有副本。完成复制后，基因对中的一个基因保持原有的功能，另一个要么消失，要么拥有一个新功能。克劳表示：“额外的基因材料为进化提供了画布，让进化过程描绘出各种景象。”克劳一直从事新奇物种和生物多样性研究。
科学家认为这种基因组复制在有颌类脊椎动物出现前就已发生。在进化树的特定枝杈(谱系)也出现完整基因组复制现象，植物要比动物更为普遍。克劳说：“我们对匙吻鲟进行的研究显示动物的完整基因组复制现象并没有此前认为的那么罕见。”（生物谷Bioon.com）
doi: 10.1093/gbe/evs067
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An independent genome duplication inferred from Hox paralogs in the American paddlefish-a representative basal ray-finned fish and important comparative reference
Karen D. Crow, Christopher D. Smith, Jan-Fang Cheng, Günter P. Wagner and Chris T. Amemiya
Vertebrates have experienced two rounds of whole genome duplication in the stem lineages of deep nodes within the group, and a subsequent duplication event in the stem lineage of the teleosts-a highly diverse group of ray-finned fishes. Here we present the first full Hox gene sequences for any member of the Acipenseriformes, the American paddlefish, and confirm that an independent whole genome duplication occurred in the paddlefish lineage, approximately 42 million years ago based on sequences spanning the entire HoxA cluster and eight genes on the HoxD gene cluster. These clusters comprise different HOX loci, and maintain conserved synteny relative to bichir, zebrafish, stickleback and pufferfish, as well as human, mouse, and chick. We also provide a gene genealogy for the duplicated fzd8 gene in paddlefish and present evidence for the first Hox14 gene in any ray-finned fish. Taken together, these data demonstrate that the American paddlefish has an independently duplicated genome. Substitution patterns of the “beta” paralogs on both the HoxA and HoxD gene clusters suggest transcriptional inactivation-consistent with functional diploidization. Further, there are similarities in the pattern of sequence divergence among duplicated Hox genes in paddlefish and teleost lineages, even though they occurred independently approximately 200 million years apart. We highlight implications on comparative analyses in the study of the “fin-limb transition” as well as gene and genome duplication in bony fishes, which includes all ray-finned fishes as well as the lobe-finned fishes and tetrapod vertebrates.
