Cryptocercus genomes expand knowledge of adaptations to xylophagy and termite sociality

Abstract

Subsociality and wood-eating or xylophagy are understood as key drivers in the evolution of eusociality in Blattodea (cockroaches and termites), two features observed in the cockroach genus Cryptocercus, the sister group of all termites. We present and analyse two new high-quality genomes from this genus, C. punctulatus from North America and C. meridianus from Southeast Asia, to explore the evolutionary transitions to xylophagy and subsociality within Blattodea. Our analyses reveal evidence of relaxed selection in both Cryptocercus and termites, indicating that a reduction in effective population size may have occurred in their subsocial ancestors. These findings challenge the expected positive correlation between dN/dS ratios and social complexity, as Cryptocercus exhibits elevated dN/dS values that may exceed those of eusocial termites. Additionally, we identify positive selection on mitochondrial ribosomal proteins and components of the NADH dehydrogenase complex, suggesting significant evolutionary changes in energy production. Future studies incorporating additional genomic data from diverse blattodean species are essential to elucidate the molecular mechanisms driving transitions to xylophagy and eusociality.