Fig 4. Social isolation triggers cannibalism and aggressiveness.

(A) Proportion (± 95% CI) of deaths in pairs of spiderlings as a function of time (days) since emergence. Unfed spiderlings were maintained in groups (yellow bars), in groups for five days before being placed in isolation (blue bars), or alone (red bars) before their introduction to test arenas. The hatched bar gives the rate of cannibalism in pairs of 20-day-old spiderlings raised socially for five days before being placed alone but that were fed three times. Sample size ranged between 24 and 30 replicates for each condition. For statistical analysis, see S4 Table. (B) Boxplots of the proportions of aggressive encounters (bite attempt, effective bite or chasing) between 20-day-old spiderlings raised in groups and unfed (yellow), raised in groups for five days before being placed in isolation (unfed: blue, fed: blue hatched), or maintained alone and unfed (red). A dot gives the proportion of aggressive encounters for each pair. Horizontal line in each box represents the median, and the lower and upper hinges indicate the first and third quartiles. Lower and higher whiskers extend to the most extreme values within 1.5 interquartile ranges from the first and third quartiles respectively. Significant difference is indicated by *** (Dunn's test, P < 0.001). Relevant data values are included in S1 Data.