Table 1 Models testing the impact of maternal loss on male chimpanzee alpha tenure, age at first siring and reproductive success.

Bold, P < 0.05; italic, P < 0.01. Reference category of factors is in parenthesis. Asterisk (*) indicates test predictor. Full versus null model comparisons: (1) Gaussian: F3,19 = 3.718, P = 0.068; (2) Gaussian: df = 1, F3,19 = 15.454, P = 0.0008; and (3) Poisson: df = 1, χ2 = 5.871, P = 0.015. Offset terms: average number of males present per conception and number of conceptions resulting in viable births across reproductive years per male. Z transformed: all continuous predictor variables. Effect sizes = R2.

TermEstimateSECIFPR2
1. Alpha tenure
Intercept2.4610.5052.121, 2.829
Orphan (yes)*1.3550.702−1.707 to −1.0333.7180.0680.163
Reproductive years1.5470.3621.191 to1.718 18.2400.00040.489
Average males per conception−0.5720.360−0.797 to 0.3742.5190.1280.117
2. Age at first siring
Intercept13.4351.20512.292 to 13.849
Orphan (yes)*3.0410.7732.763 to 3.44815.4530.00080.448
Maximum dominance0.7250.3990.519 to 0.9043.2870.0850.147
Average males per conception−0.0510.176−0.127 to 0.0650.0850.7720.004
TermEstimateSECIχ2P
3. Number of offspring
Intercept−0.0100.234−0.133 to 0.237
Orphan (yes)*−0.8630.367−1.103 to −0.7185.8720.0150.297
Alpha tenure0.3370.1380.239 to 0.4006.1330.0130.329