Molecular adjustment to a social niche: Brain transcriptomes reveal
divergent influence of social environment on the two queen morphs of the
ant Temnothorax rugatulus
Abstract
Social insects form complex societies with division of labor between
different female castes. In most species, a single queen heads the
colony; in others, several queens share the task of reproduction. These
different social organizations are often associated with distinct queen
morphologies and life history strategies and occur in different
environments. In the ant Temnothorax rugatulus, two queen morphs
- macrogynes and microgynes - exist associated with mono- and polygynous
colonies, respectively, which occur at lower and higher elevations. We
analyzed plastic changes in brain transcriptomes in response to the
social environment in these queen morphs and their workers. We
manipulated the number of queens over several weeks to investigate
whether transcriptional activity is influenced by queen morph, social
environment, or their interaction. Changes in gene expression in the
queens’ brains in response to our manipulations were subtle and largely
influenced by the interaction between social environment and queen
morph, rather than independently by these factors. Macrogynes and
microgynes thus adjust differently to their social environment.
Similarly, worker transcriptomes were influenced by an interaction
between behavioral type, i.e., nurses or foragers, and queen morph.
Nurses differentially regulated genes related to nutrition depending on
queen morph, suggesting a link between social environment and metabolic
dynamics in ant colonies. Overall, our study shed light on how the
social environment influences the molecular physiology of social
insects. Furthermore, we demonstrate that in this ant with two queen
morphs, worker physiology depends on queen morph and their role in the
colony.