The effect of tree length and shape on the power to detect amino acid toggling.

ρ, non-synonymous to synonymous rate ratio for mutations away from or towards wild type amino acid; T, toggling model where ρ is unconstrained in alternate; D, diversifying selection model.

ρ为针对发生偏离或趋近野生型氨基酸的突变的非同义突变与同义突变速率比（non-synonymous to synonymous rate ratio）；T代表切换模型（toggling model），该模型中ρ在变异状态下不受约束；D代表多样化选择模型（diversifying selection model）。