Table S5.

Investigating whether closer relatives inflict higher reproductive costs on dominants

Response	Fixed effect	β	SE	χ2	P
No. of emergent pups to which a dominant female (aged over 3 y) is assigned maternity	Intercept	−1.57	0.37
	Relatedness to female cobreeder	−0.06	0.12	0.23	0.63
	Female cobreeder age, d	0.000002	0.00003	−0.004	1.00
	No. of breeding females	0.04	0.06	0.55	0.46
	Dominant female age, d	0.0001	0.00009	1.63	0.20
	Rainfall, mm	−0.08	0.06	1.66	0.20
	Relatedness to female cobreeder × female cobreeder age	0.00002	0.0002	−0.07	1.00
Proportion of emergent litter to which a dominant female (aged over 3 y) is assigned maternity	Intercept	−0.3	0.20
	Relatedness to female cobreeder	−0.08	0.14	0.27	0.60
	Female cobreeder age, d	−0.00003	0.00004	0.53	0.47
	No. of breeding females	−0.20	0.03	58.58	<0.0001
	Dominant female age, d	0.0002	0.00007	11.93	<0.001
	Rainfall, mm	−0.06	0.03	4.40	0.036
	Relatedness to female cobreeder × female cobreeder age	−0.00005	0.0002	0.08	0.78

Shown are models predicting the number of emergent pups to which each dominant breeding female is assigned maternity (GLMM, n = 2,719 pairs of dominant females and female cobreeders, involving 131 dominant females giving birth to 337 litters in 17 groups) and the proportion of an emergent litter to which each dominant breeding female is assigned maternity (GLMM, n = 2,719 pairs of dominant females and female cobreeders, involving 131 dominant females giving birth to 337 litters in 17 groups). Models were fitted using a Poisson error structure and log-link function and a binomial error structure and logit-link function, respectively. Dominant female, cobreeder female, litter, and group ID were included as random intercepts. Significant terms are in boldface type.