Insights from long-read sequencing: Phylogenomics, genome structure, and functional genomics of Odonata

Since the publication of the first long-read draft genomes of Odonata in 2021, a flurry of long-read assemblies are published for the order. These genomes are of remarkably high quality; one assembly in particular, Pachydiplax longipennis, is near chromosome length without any scaffolding. Our research focuses on increasing our understanding of the evolution of Odonata in the areas of genomic architecture and functional genomics using genome assemblies generated with long-read sequencing technology.  By identifying regions of synteny between the genomes of two Zygoptera and two Anisoptera, we demonstrate that the chromosome architecture of the Odonata remains largely unchanged through 250 million years of evolution. We also determine that the micro-chromosome is ancestral, addressing a major unanswered question in Odonatology. We also utilize long-read genomes to uncover patterns of gene family expansion throughout Odonata, showing how these expansions are tied to the different ecological niches and evolutionary trends across various species within the order. In particular, dragonflies with a semi-terrestrial larval stage have expanded gene families related to phototransduction and UV damage, migratory dragonflies have expanded gene families tied to protein and carbohydrate metabolism, and dragonflies found in urban environments have an expanded reportoire of gene families related to immune function and the processing of free radicals. In each instance, these expanded gene families are related to the unique ecology and life history of the different sampled dragonflies. This comprehensive analysis highlights the potential of long-read sequencing in resolving complex evolutionary questions and advancing our understanding of Odonata biology.