Figure 2.

Results of a dominant removal–reintroduction experiment designed to induce contests over the rank 1 position in P. dominulus (Cant et al. 2006b). Rank 1 foundresses were removed for several days to allow rank 2 foundresses to inherit and establish themselves as replacement dominants. Mean ovarian development of rank 2s is plotted as a function of group size, which is an index of productivity. The line shows the significant least-squares regression of ovarian development on group size. Filled circles represent trials in which these newly promoted rank 2 individuals entered into an escalated fight with reintroduced rank 1 individuals; open circles represent trials in which rank 2s immediately submitted to reintroduced rank 1s. Both ovarian development and group size had significant effects on the probability of escalated conflict.