Table 3 Parameter estimates, p-values, and marginal R² for the effect of an immune challenge on mean reproductive investment. M is the mean lnRR effect size (positive value indicates increased reproductive investment for the treatment group), CI.lb and CI.ub are the lower and upper bounds of the 95% confidence interval. ^aIndicates moderators that were retained in the AICc final averaged model

Meta-analytic mean

 − 0.046

0.086

 − 0.099

0.007

Age class^a

 Unclear/mixed

 − 0.043

0.205

 − 0.110

0.024

0.037

 Old

0.167

0.171

 − 0.073

0.407

 Young

 − 0.066

0.097

 − 0.144

0.012

Control procedure

 No

 − 0.049

0.268

 − 0.136

0.038

0.000

 Yes

 − 0.045

0.074

 − 0.094

0.004

Source of animals

 Cultured population

 − 0.050

0.319

 − 0.148

0.049

0.001

 Wild or immediate offspring of wild

 − 0.049

0.136

 − 0.114

0.016

 Wild-caught but kept in research facilities for generations

 − 0.032

0.661

 − 0.176

0.112

Reproductive investment categories^a

 Behavioural traits

0.019

0.713

 − 0.081

0.118

0.029

 Offspring traits and success

 − 0.015

0.712

 − 0.095

0.065

 Others

 − 0.036

0.386

 − 0.119

0.046

 Physiological/physical traits

 − 0.048

0.358

 − 0.151

0.055

 Reproductive output

 − 0.097

0.007

 − 0.167

 − 0.027

Immune challenge type^a

 Non-pathogenic foreign bodies

0.005

0.955

 − 0.172

0.182

0.006

 Substrates of pathogenic origins

 − 0.060

0.086

 − 0.127

0.009

Blinding^a

 No/unclear

 − 0.052

0.040

 − 0.102

 − 0.002

0.003

 Yes

 − 0.012

0.900

 − 0.204

0.179

Incomplete reporting^a

 No

 − 0.050

0.129

 − 0.116

0.015

0.001

 Yes

 − 0.030

0.367

 − 0.096

0.036

Log(lifespan of species) (mean centred and controlling for research effort for that species)

 − 0.010

0.756

 − 0.068

0.048

0.002

Journal impact factor (mean centred)

0.011

0.557

 − 0.026

0.048

0.001

Year of publication (mean centred)^a

 − 0.039

0.136

 − 0.090

0.012

0.018