Phylogenies were simulated using a time-forward branching process under constant birth rates (b(t)=b) and time-dependent birth rates (b(t)=beαt) for b = 0.01, 0.03, 0.05, 0.07, and 0.09 and α = ±0.01, ±0.11, ±0.21, ±0.31, and ±0.41, for 20, 220, 420, 620, and 820 tips, and for 1, 11, 21, 31, and 41 time units. Simulated phylogenies were downsampled at 0%, 10%, 30%, 50%, and 70%. For each scenario, 100 phylogenies were simulated. Time-dependent diversification (i.e., η across subtrees) was calculated for each phylogeny simulated under each scenario. Simulations were conducted using the R packages RPANDA (R Phylogenetic ANalyses of DiversificAtion) (61) and ape (53).