Summary of selected empirical data sets used.

Ref. = Reference to original publication, seq.length = sequence length, #sequences = number of sequences, #spp. = total number of species in the data set, #spp. ≥ 5 seq. = number of species represented by 5 or more sequences.Ref. = 参考文献（Reference），指向原始发表文献；seq.length = 序列长度（sequence length）；#sequences = 序列总数（number of sequences）；#spp. = 数据集总物种数（total number of species in the data set，其中spp.为species的缩写）；#spp. ≥ 5 seq. = 拥有5条及以上序列的物种数（number of species represented by 5 or more sequences）。