Table 1.

Organismal/morphological complexity correlates with the proportion of transcriptional regulators within each kingdom when the evolutionary distance between organisms is high.

Kingdom	Species	No. of cell types	Genome size	No. of genes	No. of TFs	Proportion of TFs
Metazoa	Homo sapiens	264.5	∼ 3.3 GB	∼ 22997	∼ 1508	0.0656
	Mus musculus	130.5	∼ 2.7 GB	∼ 23873	∼ 1426	0.0597
	Tetraodon nigroviridis	119.5	∼ 390 MB	∼ 27991	∼ 1362	0.0487
	Drosophila melanogaster	59	∼ 175 MB	∼ 14141	∼ 601	0.0425
	Caenorhabditis elegans	28.5	∼ 100 MB	∼ 20140	∼ 698	0.0347
	Nematostella vectensis	22	∼ 450 MB	∼ 27273	∼ 701	0.0257
	Trichoplax adhaerens	4	∼ 50 MB	∼ 11520	∼ 233	0.0202
Viridiplantae	Zea mays	100	∼ 2.5 GB	∼ 45796	∼ 2689	0.0587
	Arabidopsis thaliana	27.25	∼ 135 MB	∼ 27235	∼ 1356	0.0498
	Selaginella moellendorffii	25	∼ 100 MB	∼ 22273	∼ 665	0.0299
	Physcomitrella patens	21	∼ 480 MB	∼ 35938	∼ 823	0.0229
	Marchantia Polymorpha	NA∗	∼ 225 MB	∼ 32718	∼ 586	0.0179
	Klebsormidium nitens	1	∼ 117 MB	∼ 16215	∼ 273	0.0168
	Chlamydomonas reinhardtii	1	∼ 107 MB	∼ 15256	∼ 213	0.0140
	Chlorella sp. NC64A	1	∼ 46.2 MB	∼ 9791	∼ 131	0.0134

The arrangement of organisms within each kingdom is based on organismal complexity. Proportion of transcriptional factors (TFs) represents the ratio of number of TFs to number of genes. Data were mostly obtained from transcription factor prediction database, only the longest transcript per gene was included in this study (http://www.transcriptionfactor.org) (Valentine et al., 1994; Bell and Mooers, 1997; McCarthy and Enquist, 2005; Vogel and Chothia, 2006; Charoensawan et al., 2010b; Burdo et al., 2014; Chen et al., 2014; Hori et al., 2014; Matsumoto et al., 2016; Jiao et al., 2017). ^∗NA, not available.