Table 5. Comparison of model fit for different generalized linear models, with taxonomic group entered as a predictor that include all possible combinations of predictor variables.

Model ranking	Intercept1	Taxonomic group	Difference in mass	Genetic distance	Interaction between group and difference in mass	Interaction between group and genetic distance	Interaction between difference in mass and genetic distance	Interaction between group, genetic distance and mass	df	logLik	AICc	delta AICc	weight
1	1.08	+2	0.85	0.85	—	—	−2.53	—	7	−117.2	249.0	0.00	0.387
2	0.79	+	0.93	3.26	—	+	−2.92	—	9	−115.3	249.3	0.35	0.325
3	1.11	+	0.78	0.93	+	—	−2.88	—	9	−116.4	251.6	2.65	0.103
4	0.82	+	0.87	3.35	+	+	−3.32	—	11	−114.5	252.1	3.11	0.082
5	1.27	+	0.37	—	—	—	—	—	5	−121.9	254.0	5.07	0.031
6	1.17	—3	0.85	0.93	—	—	−2.44	—	5	−122.1	254.5	5.59	0.024
7	0.65	+	1.19	4.51	+	+	−5.35	+	13	−113.6	254.8	5.87	0.021
8	1.25	+	0.37	0.19	—	—	—	—	6	−121.8	255.9	6.99	0.012
9	1.28	+	0.32	—	+	—	—	—	7	−121.4	257.3	8.34	0.006
10	1.10	+	0.37	1.50	—	+	—	—	8	−120.8	258.3	9.31	0.004
11	1.35	—	0.39	—	—	—	—	—	3	−126.4	259.0	10.03	0.003
12	1.26	+	0.33	0.17	+	—	—	—	8	−121.3	259.3	10.32	0.002
13	1.31	—	0.39	0.23	—	—	—	—	4	−126.3	260.7	11.79	0.001
14	1.12	+	0.34	1.46	+	+	—	—	10	−120.4	261.7	12.76	0.001
15	1.41	+	—	—	—	—	—	—	4	−137.2	282.5	33.59	0.000
16	1.40	+	—	0.12	—	—	—	—	5	−137.2	284.6	35.62	0.000
17	1.29	+	—	1.09	—	+	—	—	7	−136.6	287.8	38.81	0.000
18	1.48	—	—	—	—	—	—	—	2	−143.5	291.1	42.19	0.000
19	1.47	—	—	0.09	—	—	—	—	3	−143.5	293.2	44.20	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 plus sign (+) indicates that the predictor variable (factor) was included in the model.

³ long dash (—) indicates that the predictor variable was absent from the model.