Table 1.

Number of offspring sired by male house mice

Fixed effects	Coefficient (SE)	z-value	P-value	ΔAIC	Random effects	Variance (SD)
Model for total number of offspring sired
Intercept	−26.14 (5.42)	−4.83	<0.001	-	Sibling group	0.47 (0.69)
Body mass	4.52 (1.55)	2.91	0.004	-	Population	0.37 (0.61)
Testes mass	19.43 (6.50)	2.99	0.003	5.82
Seminal vesicles mass	8.53 (3.35)	2.54	0.011	3.71
Baculum shaft width	32.24 (5.32)	6.06	<0.001	45.04

Generalized linear mixed model to investigate morphological traits influencing the reproductive success of male house mice, showing the best model for the total number of offspring sired. Data for morphological traits were log transformed prior to analysis. Body mass was retained in the model as a covariate. Population and sibling group were included as random effects (see text for further details). ΔAIC = the change in the AIC if the single term is dropped. Number of observations = 22, sibling groups = 11, populations = 4.