Closely related ants exhibit species-specific transcriptional responses during temperature acclimation

Abstract Ambient temperature is a major selective pressure, affecting traits from development to survival. In insects, cuticular hydrocarbons (CHCs) reduce water loss and can be adjusted during acclimation; however, the molecular basis and evolutionary conservation of this plasticity remain poorly understood. We examined transcriptional responses of 3 congeneric Lasius ant species from distinct habitats acclimated to 2 constant and 1 fluctuating temperature regimes. We analyzed global gene (co-)expression patterns and candidate genes involved in CHC biosynthesis. All acclimation treatments induced changes in gene expression, with fluctuating temperatures eliciting the fewest. The arboreal Lasius brunneus showed the weakest response and uniquely lacked increased desiccation resistance, indicating lower plasticity relative to Lasius niger and Lasius platythorax. Coexpression networks revealed that CHC-related genes were broadly distributed across modules, whereas global expression patterns were highly conserved across species. These results highlight species-specific plasticity within a conserved transcriptional framework, with implications for resilience to climate change.