Table 1. Summary statistics and heritabilities (with s.e.) due to sires (h2sire) and dams (h2dam).
| Trait | N | Mean (s.e.) | Varsire | VarDam | Varresidual | h2sire (s.e.) | h2dam | Pdiff | Psire | CVP | CVA | CVR |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sperm head (μm) | 451 | 3.93 (0.008) | 0.01 | 0.002 | 0.02 | 1.45 (0.31) | 0.28 (0.15) | 0.007 | <0.0001 | 4.27 | 5.14 | 0a |
| Midpiece (μm) | 451 | 5.35 (0.041) | 0.17 | 0.11 | 0.52 | 0.85 (0.30) | 0.54 (0.21) | >0.1 | <0.0001 | 16.72 | 15.42 | 6.46 |
| Flagellum (μm) | 451 | 43.41 (0.070) | 0.53 | 0.22 | 1.48 | 0.96 (0.28) | 0.42 (0.19) | 0.082 | <0.0001 | 3.44 | 3.37 | 0.70 |
| Total sperm length (μm) | 451 | 52.69 (0.071) | 0.63 | 0.21 | 1.40 | 1.12 (0.30) | 0.39 (0.18) | 0.035 | <0.0001 | 2.84 | 3.00 | 0a |
| VAP (μs−1)b | 450 | 85.28 (0.73) | 47.82 | 15.31 | 182.13 | 0.78 (0.26) | 0.25 (0.16) | 0.035 | <0.0001 | 18.36 | 16.22 | 8.62 |
| ALH (μm) | 450 | 4.47 (0.065) | 0.20 | 0.13 | 1.58 | 0.41 (0.20) | 0.29 (0.18) | >0.1 | 0.002 | 30.85 | 19.78 | 23.67 |
| BCF (Hz) | 450 | 29.56 (0.209) | 1.02 | 0.91 | 17.79 | 0.21 (0.14) | 0.20 (0.16) | >0.1 | 0.005 | 15.02 | 6.84 | 13.37 |
| Sperm viability (%)b | 449 | 59.84 (0.10) | 83.88 | ∼0.00 | 207.17 | 1.15 (0.24) | ∼0 | <0.0001 | <0.0001 | 28.53 | 30.63 | 0a |
Abbreviations: ALH, amplitude of lateral head displacement; BCF, beat cross frequency; VAP, average path velocity.
Estimates of sire, dam (nested within sire) and residual variance components (Varsire, Vardam and Varresidual) are taken from nested mixed-models using REML estimation (see Materials and methods). Sire and dam heritabilities were compared using the delete-one sire jackknife procedure (see Materials and methods). P-values from paired t-tests (Pdiff) are given for these comparisons. Tests for the significance of sire additive genetic variance (Psire) come from likelihood ratio tests (see text for details). Samples sizes (N), mean values and coefficients of phenotypic, additive genetic and residual variation (CVP, CVA and CVR, respectively) are provided for each trait. Coefficients of variation were calculated according to the formulae: CVP=100 × √VP/X; CVA=100 × √VA/X; CVR=100 × √VP−VA/X, where VA=4 × VarSire, VP=Varsire+VarDam+Varresidual and X=trait mean.
Where estimates of VA exceed VP, CVR values were set to zero.
Data for VAP and sperm viability were re-analysed from Evans (2010).