Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403.
Presidential Initiative in Data Science, University of Oregon, Eugene, OR 97403.
Proc Natl Acad Sci U S A. 2022 Jun 28;119(26):e2119602119. doi: 10.1073/pnas.2119602119. Epub 2022 Jun 22.
Seadragons are a remarkable lineage of teleost fishes in the family Syngnathidae, renowned for having evolved male pregnancy. Comprising three known species, seadragons are widely recognized and admired for their fantastical body forms and coloration, and their specific habitat requirements have made them flagship representatives for marine conservation and natural history interests. Until recently, a gap has been the lack of significant genomic resources for seadragons. We have produced gene-annotated, chromosome-scale genome models for the leafy and weedy seadragon to advance investigations of evolutionary innovation and elaboration of morphological traits in seadragons as well as their pipefish and seahorse relatives. We identified several interesting features specific to seadragon genomes, including divergent noncoding regions near a developmental gene important for integumentary outgrowth, a high genome-wide density of repetitive DNA, and recent expansions of transposable elements and a vesicular trafficking gene family. Surprisingly, comparative analyses leveraging the seadragon genomes and additional syngnathid and outgroup genomes revealed striking, syngnathid-specific losses in the family of fibroblast growth factors (FGFs), which likely involve reorganization of highly conserved gene regulatory networks in ways that have not previously been documented in natural populations. The resources presented here serve as important tools for future evolutionary studies of developmental processes in syngnathids and hold value for conservation of the extravagant seadragons and their relatives.
海龙鱼是海龙科中一种非凡的硬骨鱼谱系，以雄性怀孕而闻名。海龙鱼包括三个已知物种，以其奇幻的身体形态和颜色而广为人知和赞赏，其特定的栖息地要求使它们成为海洋保护和自然历史利益的旗舰代表。直到最近，海龙鱼仍然缺乏重要的基因组资源。我们已经为叶海龙和草海龙生成了基因注释的染色体规模基因组模型，以推进对海龙鱼以及它们的海龙鱼和海马近亲的进化创新和形态特征的研究。我们确定了几个海龙鱼基因组特有的有趣特征，包括在一个对表皮外生发育重要的发育基因附近的非编码区的分歧，广泛存在重复 DNA，以及转座元件和囊泡运输基因家族的近期扩张。令人惊讶的是，利用海龙鱼基因组和其他海龙科和外群基因组进行的比较分析揭示了一个显著的、海龙科特有的成纤维细胞生长因子（FGF）家族的缺失，这可能涉及到高度保守的基因调控网络的重组，而这种重组方式以前在自然种群中尚未有记录。这里呈现的资源是未来对海龙科发育过程进行进化研究的重要工具，并对保护华丽的海龙鱼及其亲属具有价值。
