Getting Over It: Maternal Stress and Gut Microbiome Manipulations Do Not Affect Rates of Offspring Habituation During Long Bouts of Stress.

Conspecific competitive interactions occur in a variety of contexts, including for resources and territory. These competitive interactions can vary in frequency and duration. The amount of aggression displayed and whether individuals alter their aggressive response during longer competitive bouts may be impacted by individual differences in stress response and behavior. The maternal environment, including maternal stress and the maternal microbiome, can have sex-specific, developmental effects on offspring's physiology and aggressive behavior. We tested whether the maternal environment affects changes to offspring aggressive behavior during long competitive bouts in Siberian hamsters (Phodopus sungorus). We exposed pregnant females to one of four treatments (social stressor, microbiome manipulation, combined social stress and microbiome manipulation, or no treatment) for ten days. Using a resident-intruder behavioral paradigm, adolescent offspring were exposed to a same-sex intruder for 15 min. We assessed differences in offspring behavioral responses during the first and last 5 min of the competitive interaction. All offspring displayed less aggression during the last 5 min compared to the first 5 min, regardless of maternal treatment. Regardless of maternal treatment, both female and male offspring reduced social behavior towards the intruder, while increasing non-social and decreasing anxiety like behavior across the 15-min trial. Our results are consistent with habituation towards an intruder and indicate that early development does not affect habituation during aggression with a conspecific, further confirming the complexity and highly conserved mechanisms involved in habituation.