Table 1. Comparison of model fit for different linear mixed-effects models that include all possible combinations of predictor variables.

Model ranking	Intercept1	Difference in mass	Genetic distance	Interaction between difference in mass and genetic distance	df	logLik	AICc	delta AICc	weight
1	1.17	0.84	0.91	−2.46	6	−120.5	253.3	0.00	0.882
2	1.35	0.37	—	—	4	−124.9	258.0	4.72	0.083
3	1.31	0.37	0.24	—	5	−124.8	259.8	6.49	0.034
4	1.47	—2	—	—	3	−140.5	287.1	33.85	0.000
5	1.45	—	0.14	—	4	−140.5	289.1	35.83	0.000

Models tested the prediction that the advantage of large size in aggressive contests for resources declines with genetic distance among interacting bird species (n = 244 species pairs).

¹ numbers for predictor variables are effect sizes.

² long dash (—) indicates that the predictor variable was absent from the model.