Figure 4.

Predicted ARS is shown for lance-tailed manakin alphas of different age and tenure classes. Predicted values are derived from the bootstrapped mean parameter estimates of the best-fit model, which explained ARS as a function of alpha tenure year, individual age, age², and final year of alpha status (table 2). Declines in average annual siring success at advanced ages indicate senescence in fecundity after males reach 8.6 years after hatching. Note that despite this effect of senescence, individual males are expected to increase in siring success with each successive year of alpha status owing to positive effects of successive tenure classes and the linear term for age. Predicted values that fall below the grey line indicate that a male of the identified age and status category is unlikely to sire any chick. The influence of the final year of alpha status received weak support in the final model and is not shown graphically. Confidence intervals of model predictions for specific tenure categories are presented in the electronic supplementary material, figure S1. Filled circles, tenure year 1; open circles, tenure year 2; inverted filled triangles, tenure year 3; open triangles, tenure year 4; filled squares, tenure year 5; open squares, tenure year 6; filled diamonds, tenure year 7.