Content area
This thesis advances insect evolutionary developmental biology by integrating high-resolution transcriptomic and morphological data across four phylogenetically diverse insect species: Thermobia domestica (Zygentoma), Ephemera vulgata (Ephemeroptera), Ischnura elegans (Odonata), and Nasonia vitripennis (Hymenoptera). These taxa span key evolutionary transitions and developmental modes, thereby capturing stages of insect evolution and development underrespresented through traditional model systems. Using DAPI staining and RNA-seq across multiple embryonic stages, I generated temporal gene expression atlases along with morphological documentation, enabling detailed comparisons of embryogenesis.Individual transcriptomic analyses of T. domestica (Chapter 2) and E. vulgata (Chapter 3) identified major transcriptional turning points, particularly the maternal-to-zygotic transition and katatrepsis, and revealed conserved temporal activation of developmental processes. Expression of Hox genes in E. vulgata supports ancestral sequential segmentation. The results of the transcriptome assembly of I. elegans and N. vitripennis are reported on as well (Chapter 4).By comparing orthologous gene expression across species, including Drosophila melanogaster, I aligned their developmental timepoints (Chapter 5). Using correlation strength as a proxy for evolutionary conservation, I revealed evolutionary heterochrony and refined the hourglass model previously reported in Diptera. Conservation peaked earlier in development among distant taxa, consistent with a nested hourglass pattern. Additionally, larval and pupal stages of holometabolous insects reflected a distributed recapitulation of mid- to late embryogenesis in ametabolous and hemimetabolous insects, rather than aligning with a single stage. These findings emphasize the evolutionary value of non-model insects and expand available resources for comparative evo-devo research.