Table 1. Descriptive statistics of testis morphology and sperm quantity in eight species of Australian Maluridae.
| Superb Fairy-wren | Splendid Fairy-wren | Variegated Fairy-wren | Blue-breasted Fairy-wren | White-winged Fairy-wren | Red-backed Fairy-wren | Southern Emu-wren | Striated Grasswren | |
| Body mass (g) | 8.93±0.22 (6) | 9.45±0.06 (94) | 8.29±0.12 (33) | 9.27±0.14 (15) | 7.7±0.12 (13) | 7.57±0.05 (76) | 7.32±0.11 (6) | 19.23±0.27 (3) |
| CTM (g) | 0.29±0.04 | 0.30±0.02 | 0.18±0.01 | 0.13±0.02 | 0.33±0.02 | 0.21±0.01 | 0.045±0.004 | 0.34±0.009 |
| GSI | 3.39±0.48 | 3.56±0.25 | 2.38±0.15 | 1.49±0.24 | 4.45±0.23 | 2.95±0.18 | 0.62±0.06 | 1.81±0.04 |
| Sperm tissue | 99.60±0.11 | 99.33±0.09 | 99.37±0.05 | 99.01±0.25 | 99.63±0.06 | 99.74±0.06 | 98.99±0.12 | 99.29±0.03 |
| CP volume (mm3) | 105.08±11.8 (6) | 96.99±3.27 (94) | 36.44±3.15 (34) | 31.39±3.36 (14) | 86.96±8.63 (13) | 128.24±3.36 (76) | 0 (6) | 94.15±9.47 (3) |
| SG mass (g) | 0.09±0.007 (6) | 0.09±0.01 (6) | 0.05±0.006 (5) | 0.04±0.01 (5) | 0.09±0.006 (6) | 0.05±0.004 (16) | 0.01±0.002 (6) | 0.05±0.01 (3) |
| Sperm reserves (×106) | 318.69±53.3 (6) | 276.47±9.48 (6) | 161.82±29.4 (5) | 94.55±23.45 (5) | 276.66±16.7 (6) | 195.0±0.01 (16) | 12.58±4.59 (6) | 42.46±6.14 (3) |
| Ejaculate size (×106) | 33.36±8.96 (6) | 48.37±3.82 (87) | 8.54±1.64 (24) | 15.16±2.49 (15) | 45.69±5.15 (13) | 36.13±3.0 (76) | 0* (6) | 6.56±2.18 (3) |
CTM = combined testes mass, GSI = gonadosomatic index.
Cloacal protuberance (CP) volume and seminal glomera (SG) mass represent indirect measures of sperm quantity, while the number of sperm in sperm stores (sperm reserves) and the number of sperm in ejaculate samples (ejaculate size) represent direct measures of sperm quantity.
Species differed significantly in all four measures of sperm quantity: CP volume (ANOVA: F 7,238 = 43.66, P<0.001), SG mass (ANOVA, F 7,45 = 20.96, P<0.001), sperm reserves (ANOVA, F 7,46 = 18.94, P<0.001), and ejaculate size (ANOVA, F 6,217 = 8.87, P<0.001).
*Ejaculate samples were not collected from the southern emu-wren due to logistical problems during the 2006 field season.
Sample sizes for all traits are shown in Supplementary Table 1.