Evolution and development are two inherently intertwined processes. As the embryo develops it does so in ways that both reflect past constraints and bias the future evolution of the species. While research exploiting this insight typically studies individual genes, transcriptomic analyses have sparked a new wave of discoveries. In this opinion piece, I review the evidence arising from transcriptomics on the topics of the evolution of germ layers, the phylotypic stage, and developmental constraints. The spatiotemporal pattern of gene expression across germ layers provides evidence that the endoderm was the first germ layer to evolve. Comparing transcriptome dynamics throughout developmental time across distant species reveals a mid-developmental transition under strong developmental constraints. These studies highlight the efficiency of exploratory data analysis using computational tools and comparative approaches for discovery.

进化与发展是两个内在交织的过程。随着胚胎的发展，它既反映过去的局限性，又偏向物种的未来进化。尽管利用这种见解进行的研究通常会研究单个基因，但转录组学分析引发了新的发现浪潮。在这篇观点中，我回顾了转录组学中有关细菌层的进化，系统发育阶段和发育限制等主题的证据。跨胚层的基因表达的时空模式提供了内胚层是第一个进化的胚层的证据。比较整个遥远物种在整个发育过程中的转录组动力学，发现在强大的发育约束下，发育中期过渡。