Figures & data
Figure 1. Time-line diagram of the experimental protocol. 30 breeding pairs (10 per taxon) were established (Day 0), with parturition of the first litter at Days 23–25. Offspring from the first litter were removed at 25 days of age (Days 48–50) just prior to the birth of the second litter. Pairs raised their second litter until juvenile males (30 per taxon) were allocated to one of three treatments at 25 days of age (Days 73–75). Juvenile males remained in their treatments for 10 days until 35 days of age and tested in a four-arm maze (Days 83–85). 20 min later, blood was taken from all males for corticosterone analysis. Blood for corticosterone analysis was collected again 10 days later at 45 days of age (Days 93–95) without exposure to the four-arm maze.
Figure 2. Time (s) spent by juvenile male striped mice Rhabdomys of three taxa, reared in three conditions, in the (a) light and (b) dark arms of a modified four-arm maze. n = 30 mice per taxon, 10 mice per treatment. Data are mean + SEM. Statistics: GLM with multiple dependents. Bars with different letters indicate significant differences (Tukey HSD post hoc tests; p < 0.05).
Figure 3. Number of visits to (a) light and (b) dark arms of a modified four-arm maze by juvenile male striped mice Rhabdomys of three taxa, reared in three conditions. n = 30 mice per taxon, 10 mice per treatment. Data are mean + SEM. Statistics: GLM with multiple dependents. Bars with different letters indicate significant differences (Tukey HSD post hoc tests; p < 0.01).
Table 1. The behavioral responses of male striped mice of three taxa in a modified four-arm maze.
Figure 4. Serum corticosterone concentrations (ng/ml) of juvenile male striped mice Rhabdomys of three taxa reared in three conditions, after a 10 min period in a modified four-arm maze. Data are mean + SEM. n = 30 mice per taxon, 10 mice per treatment. Statistics: GLM design. Bars with different letters indicate significant differences (Tukey HSD post hoc tests; p < 0.05).
Figure 5. Change in corticosterone concentrations in individuals in philopatric (column 1), separated (column 2) and isolated (column 3) juvenile male striped mice 20 min after exposure to a four-arm maze and 10 days later. Row 1 is the group-living R. pumilio and rows 2 and 3 are the solitary R. d. dilectus and R. d. chakae, respectively (n = 10 for each taxon and treatment, except R. d. dilectus separated (n = 9) and isolated (n = 8), and R. d. chakae isolated (n = 9). The mean percentage change in concentrations (Δ) is presented inside each figure for significant within taxon differences: R. pumilio philopatric, p = 0.003, separated, p = 0.023; R. d. dilectus, separated, p = 0.003 (paired-t test).
