Ewart, Kyle M.Ho, Simon Y.W.Chowdhury, Al AabidJaya, Frederick R.Kinjo, YukihiroBennett, JunoBourguignon, ThomasRose, Harley A.Lo, Nathan2025-05-302025-05-300962-8452PubMed:38772424WOS:001229011200001http://www.scopus.com/inward/record.url?scp=85194025963&partnerID=8YFLogxKhttps://hdl.handle.net/1885/733754664Genetic changes that enabled the evolution of eusociality have long captivated biologists. More recently, attention has focussed on the consequences of eusociality on genome evolution. Studies have reported higher molecular evolutionary rates in eusocial hymenopteran insects compared with their solitary relatives. To investigate the genomic consequences of eusociality in termites, we analysed nine genomes, including newly sequenced genomes from three non-eusocial cockroaches. Using a phylogenomic approach, we found that termite genomes have experienced lower rates of synonymous substitutions than those of cockroaches, possibly as a result of longer generation times. We identified higher rates of non-synonymous substitutions in termite genomes than in cockroach genomes, and identified pervasive relaxed selection in the former (24-31% of the genes analysed) compared with the latter (2-4%). We infer that this is due to reductions in effective population size, rather than gene-specific effects (e.g. indirect selection of caste-biased genes). We found no obvious signature of increased genetic load in termites, and postulate efficient purging of deleterious alleles at the colony level. Additionally, we identified genomic adaptations that may underpin caste differentiation, such as genes involved in post-Translational modifications. Our results provide insights into the evolution of termites and the genomic consequences of eusociality more broadly.We utilized the Artemis HPC cluster provided by the University of Sydney, the FlashLite HPC cluster provided by the University of Queensland's Research Computing Centre (RCC), and the Nimbus cloud service provided by the Pawsey Supercomputing Centre. We thank Carolyn Hogg and Parice Brandies for advice on high performance computing resources.11enPublisher Copyright: © 2024 The Authors.Blattodeaeffective population sizeeusocialityindirect selectionphylogenomicsrelaxed selectionEusocialityRelaxed selectionIndirect selectionEffective population sizePhylogenomics2024-05-2210.1098/rspb.2023.243985194025963