Transposable elements (TEs) are self-replicating genetic sequences and are often described as important ‘drivers of evolution’. This driving force is because TEs promote genomic novelty by enabling rearrangement, and through exaptation as coding and regulatory elements. However, most TE insertions potentially lead to neutral or harmful outcomes, therefore host genomes have evolved machinery to suppress TE expansion. Through horizontal transposon transfer (HTT) TEs can colonize new genomes, and since new hosts may not be able to regulate subsequent replication, these TEs may proliferate rapidly. Here, we describe HTT of the Harbinger-Snek DNA transposon into sea kraits (Laticauda), and its subsequent explosive expansion within Laticauda genomes. This HTT occurred following the divergence of Laticauda from terrestrial Australian elapids approximately 15–25 Mya. This has resulted in numerous insertions into introns and regulatory regions, with some insertions into exons which appear to have altered UTRs or added sequence to coding exons. Harbinger-Snek has rapidly expanded to make up 8–12% of Laticauda spp. genomes; this is the fastest known expansion of TEs in amniotes following HTT. Genomic changes caused by this rapid expansion may have contributed to adaptation to the amphibious-marine habitat.

转座因子 (TE) 是自我复制的基因序列，通常被描述为重要的“进化驱动因素”。这种驱动力是因为 TE 通过实现重排以及作为编码和调节元件的扩展来促进基因组的新颖性。然而，大多数 TE 插入可能导致中性或有害结果，因此宿主基因组已经进化出抑制 TE 扩增的机制。通过水平转座子转移 (HTT) TEs 可以定植新的基因组，并且由于新宿主可能无法调节随后的复制，这些 TEs 可能会迅速增殖。在这里，我们描述了Harbinger-Snek DNA 转座子进入海环蛇 ( Laticauda ) 的HTT ，以及其随后在Laticauda 中的爆炸性扩张基因组。这种 HTT 发生在Laticauda与澳大利亚陆地 elapids 大约 15-25 Mya的分歧之后。这导致大量插入到内含子和调节区中，其中一些插入到外显子中，这些外显子似乎改变了 UTR 或向编码外显子添加了序列。Harbinger-Snek迅速扩大到占Laticauda spp 的8-12% 。基因组；这是继 HTT 之后羊膜中 TE 已知最快的扩张。这种快速扩张引起的基因组变化可能有助于适应两栖海洋栖息地。