Table 1. Numbers and proportion of X- and Y-chromosome-bearing spermatozoa in the ejaculates of individual pygmy hippopotamus bulls.
| Bull | Y* | X* | Y/(X+Y) | P† |
|---|---|---|---|---|
| 1 | 876 | 1143 | 0.4339 | <0.00001 |
| 2 | 951 | 1325 | 0.4178 | <0.00001 |
| 3 | 854 | 1194 | 0.4170 | <0.00001 |
| 4 | 918 | 1186 | 0.4363 | <0.00001 |
| 5 | 881 | 1129 | 0.4383 | <0.00001 |
| 6 | 931 | 1206 | 0.4357 | <0.00001 |
| 7 | 959 | 1203 | 0.4436 | 0.00001 |
| 8 | 939 | 1223 | 0.4343 | <0.00001 |
| 9 | 935 | 1215 | 0.4349 | <0.00001 |
| 10 | 899 | 1121 | 0.4450 | <0.00001 |
| Mean |
|
|
0.4337 |
0.005‡ |
* The number of X- or Y-chromosome-bearing spermatozoa, respectively, as identified by fluorescence in situ hybridization (FISH).
† Binomial test, exact cumulative probabilities, two-tailed, against the expected ratio of 0.5.
‡ Wilcoxon signed-ranks test, two-tailed, using the proportion of Y-chromosome-bearing spermatozoa against the expected ratio of 0.5.