The influence of the postnatal maternal environment in accounting for differences in aggression and behavioural strategies in Mus domesticus

House mice of selection lines for short attack latency (SAL) and long attack latency (LAL) differ fundamentally in the way they interact with their environment. A previous study showed marked differences in maternal behaviour between dams from both lines. The present study was designed to determine, by reciprocal cross-fostering, to what extent the postnatal SAL and LAL maternal environment contributes to observed differences in aggression and behavioural strategy between SAL and LAL mice. At a subadult age there were neither differences in attack latency between lines nor between control and cross-fostered groups. In adulthood there was a significant difference in attack latency between SAL and LAL mice, which was not influenced by maternal type. Also coping, as measured by the readiness to encounter a challenge, was not influenced by maternal type. Both at a subadult age as in adulthood, SAL mice encountered unknown situations much faster than LAL mice, but there were no differences between control and cross-fostered groups. As found in previous studies, SAL mice were more routine-like in their behaviour than LAL mice. However, SAL mice that were reared by LAL dams were more flexible in their behaviour than SAL mice reared by their own mothers. This postnatal maternal effect on behavioural flexibility was not found in LAL mice. It can be concluded that the significant difference in early experience between SAL and LAL mice, due to different patterns of maternal effort, hardly contributes to the consistent differences in aggression, coping and behavioural flexibility between SAL and LAL mice.