Complex effects of testosterone level on ectoparasite load in a ground squirrel: an experimental test for the immunocompetence handicap hypothesis

Table 1 Results of conditional model averaging, based on negative binomial generalized linear mixed-effects model on ectoparasite load (whole data set) of Daurian ground squirrels (Spermophilus dauricus)

Model/factors	Estimate	Standard error	Z value	P value	VIF
TickLoad_after
Intercept	23.15	20.88	1.07	0.28	NA
FleaLoad_after	2.16	1.17	1.74	0.082	1.32
Sex (male)	7.31	20.22	0.34	0.73	2.40
Treatment (testosterone)	− 2.62	18.63	0.13	0.89	2.48
Sex: treatment	61.13	27.58	2.10	0.036	2.84
TickLoad_before	0.39	0.29	1.29	0.20	1.44
Body weight	−0.23	0.17	1.31	0.19	1.26
FleaLoad_after
Intercept	3.32	3.38	0.94	0.35	NA
TickLoad_after	0.050	0.027	1.73	0.084	3.20
Sex (male)	1.87	2.70	0.66	0.51	2.69
Treatment (testosterone)	1.78	2.47	0.68	0.50	1.87
Sex: treatment	0.56	4.38	0.12	0.90	5.50
FleaLoad_before	0.41	0.27	1.41	0.15	3.10
Body weight	0.018	0.033	0.50	0.62	2.90

TickLoad_after and FleaLoad_after refer to tick load and flea load recorded in the second round of ectoparasite check, respectively. TickLoad_before and FleaLoad_before refer to tick load and flea load recorded in the first round of ectoparasite check, respectively. Variance inflation factor (VIF) for each explanatory factory is indicated. Significant terms marked by bold

ISSN: 1756-3305