Lungfishes belong to lobe-fined fish (Sarcopterygii) that, in the Devonian period, ‘conquered’ the land and ultimately gave rise to all land vertebrates, including humans^1,2,3. Here we determine the chromosome-quality genome of the Australian lungfish (Neoceratodus forsteri), which is known to have the largest genome of any animal. The vast size of this genome, which is about 14× larger than that of humans, is attributable mostly to huge intergenic regions and introns with high repeat content (around 90%), the components of which resemble those of tetrapods (comprising mainly long interspersed nuclear elements) more than they do those of ray-finned fish. The lungfish genome continues to expand independently (its transposable elements are still active), through mechanisms different to those of the enormous genomes of salamanders. The 17 fully assembled lungfish macrochromosomes maintain synteny to other vertebrate chromosomes, and all microchromosomes maintain conserved ancient homology with the ancestral vertebrate karyotype. Our phylogenomic analyses confirm previous reports that lungfish occupy a key evolutionary position as the closest living relatives to tetrapods^4,5, underscoring the importance of lungfish for understanding innovations associated with terrestrialization. Lungfish preadaptations to living on land include the gain of limb-like expression in developmental genes such as hoxc13 and sall1 in their lobed fins. Increased rates of evolution and the duplication of genes associated with obligate air-breathing, such as lung surfactants and the expansion of odorant receptor gene families (which encode proteins involved in detecting airborne odours), contribute to the tetrapod-like biology of lungfishes. These findings advance our understanding of this major transition during vertebrate evolution.

肺鱼属于肺鳍鱼（Sarcopterygii），在泥盆纪时期“征服”了陆地并最终产生了所有陆地脊椎动物，包括人类^1,2,3 。在这里，我们确定了澳大利亚肺鱼（ Neoceratodus forsteri ）的染色体质量基因组，该基因组是已知动物中最大的基因组。该基因组规模巨大，比人类基因组大约 14 倍，主要归因于巨大的基因间区域和重复含量高（约 90%）的内含子，其组成部分类似于四足动物（主要包括长散布的基因组）。核元素）比射线鳍鱼更多。肺鱼基因组通过与蝾螈巨大基因组不同的机制继续独立扩展（其转座元件仍然活跃）。 17条完全组装的肺鱼大染色体与其他脊椎动物染色体保持同线性，所有小染色体与祖先脊椎动物核型保持保守的古代同源性。我们的系统发育学分析证实了之前的报道，即肺鱼作为四足动物最接近的近亲，占据着关键的进化地位^4,5 ，强调了肺鱼对于理解与陆地化相关的创新的重要性。肺鱼对陆地生活的预适应包括在其分叶鳍中获得类似肢体的表达，例如hoxc13和sall1 。 进化速度的加快和与专性空气呼吸相关的基因的复制，例如肺表面活性剂和气味受体基因家族（编码参与检测空气气味的蛋白质）的扩展，有助于肺鱼的四足动物生物学。这些发现增进了我们对脊椎动物进化过程中这一重大转变的理解。