From: Social dominance explains within-ejaculate variation in sperm design in a passerine bird
a) Difference (after – before) in the variation in sperm design | ||||
Random effects | Estimates ± SE |  | Z | P |
 Aviary | 0.010 ± 0.010 |  | 0.91 | 0.18 |
 Sampling date | 0.007 ± 0.012 |  | 0.58 | 0.28 |
Fixed effects | Â | F | df | P |
 Intercept | 1.115 ± 1.061 |  |  |  |
 Difference in social rank | -0.010 ± 0.025 | 0.18 | 1, 50.8 | 0.68 |
 Body mass (after) | -0.027 ± 0.026 | 1.09 | 1, 47.3 | 0.30 |
 Tarsus length | -0.026 ± 0.050 | 0.27 | 1, 46 | 0.60 |
b) Difference (after – before) in the variation in total sperm length | ||||
Random effects | Estimates ± SE |  | Z | P |
 Aviary | 0.107 ± 0.103 |  | 1.04 | 0.15 |
 Sampling date | 0.091 ± 0.141 |  | 0.64 | 0.26 |
Fixed effects | Â | F | df | P |
 Intercept | 10.258 ± 3.224 |  |  |  |
 Difference in social rank | -0.131 ± 0.075 | 3.04 | 1, 50.6 | 0.09 |
 Body mass | -0.090 ± 0.080 | 1.26 | 1, 46.8 | 0.27 |
 Tarsus length | -0.427 ± 0.150 | 8.08 | 1, 45.7 | 0.007 |