Appendix.

Summary of analyzed knockouts and additional analyses

Knockout ID	Date	Group ID	Dominance rank at time of knockout	Type of dispersal	Age in years at time of knockout
28	12-Feb-1984	1	2	unknown	7.8
29	21-Oct-1984	2	2	dispersal	8.1
26	19-Apr-1986	1	1	unknown	9.0
27	6-Jun-1986	1	2	dispersal	8.5
25	31-Oct-1987	2	2	unknown	8.1
24	2-Nov-1988	2	1	dispersal	9.3
23	26-Jan-1993	2	1	dispersal	10.2
22	22-Jul-1995	2.2	2	unknown	8.2
21	6-Mar-1996	2.1	2	dispersal	9.4
20	17-Nov-1997	1.2	1	unknown	9.3
19	9-Jan-2000	2.2	2	dispersal	10.1
17	20-Apr-2000	1.22	2	dispersal	13.5
18	23-Aug-2000	1.22	1	unknown	8.2
16	2-Oct-2000	1.21	2	unknown	14.0
15	16-May-2001	1.21	2	unknown	6.0
14	5-Jan-2002	1.21	2	dispersal	12.2
12	8-May-2004	1.21	2	death	8.3
13	13-Oct-2004	1.21	2	dispersal	13.6
11	13-Aug-2005	2.1	1	unknown	10.5
10	5-Dec-2005	2.1	1	dispersal	8.0
8	13-Mar-2006	1.1	2	unknown	7.6
9	22-May-2006	2.2	2	dispersal	12.6
7	20-Apr-2008	2.1	2	dispersal	10.2
6	4-Jun-2008	1.21	2	dispersal	11.1
4	9-Apr-2009	1.21	1	unknown	9.6
5	23-Sep-2009	1.21	1	death	10.3
3	30-Jul-2010	1.1	1	dispersal	11.4
2	6-Aug-2010	1.21	2	dispersal	8.5
1	4-Mar-2011	1.21	2	dispersal	9.8

We repeated the analysis described in the main text separately for all knockouts of alpha male and all knockouts of beta males. The results of these analyses (Supplementary Fig. 1, 2) are very similar to results reported in the main text, indicating that alpha and beta males did not have different effects on grooming and association rates. However, with the reduced statistical power associated with the smaller number of data points in each analysis, we found no significant effect of knockouts.