Table 2.
Female-mediated cues of sperm competition risk do not affect ejaculation frequency (A–C), presented as the mean number of ejaculations per bout (and in brackets as the percentage of trials with double ejaculation) or sperm allocation per ejaculate (D and E)
| Male ejaculate allocation | Female cues of sperm competition risk | χ2 /t | df | P | ||
|---|---|---|---|---|---|---|
| (A) | 1. Mean ejaculation number per female (percentage of parings where male ejaculated twice) | Familiar | Unfamiliar | 0.26 | 1 | 0.61 |
| 1.18 (18%) | 1.27 (27%) | |||||
| (B) | Early oestrus | Late oestrus | 0 | 1 | 1.00 | |
| 1.18 (18%) | 1.18 (18%) | |||||
| (C) | Unmated | Mated | 0.05 | 1 | 0.83 | |
| 1.18 (18%) | 1.14 (14%) | |||||
| (D) | 2. Mean sperm number per ejaculate (×106, ±standard error) | Familiar, early oestrus | Unfamiliar, early oestrus | 0.75 | 10 | 0.47 |
| 5.74±0.75 | 5.48±1.21 | |||||
| (E) | Familiar, late oestrus | 0.73 | 9 | 0.48 | ||
| 5.45±0.94 | ||||||
Statistical tests represent paired comparisons of subjects matched for other female cues of sperm competition risk; see main text for detailed description of these female-mediated cues. Test statistics for ejaculation frequency are based on chi-square tests of an association between treatment group and outcome (single or double ejaculation), and for sperm allocation on paired t-tests on the log-transformed sperm count data.