Table 1.

The enrichment of molecular functions in the urancestral FSF sets

Urancestor	Functional sub-categories (categories)	Urancestral FSFs (sample)	Extant FSFs (bkgd)	Rate for sample	Rate for bkgd	Ratio	P value
min_set	Transferases (Metabolism)	6	29	0.066	0.020	4.19	0.0021
	Small molecule binding (General)	4	22	0.057	0.016	3.68	0.021
	Nucleotide m/tr (Metabolism)	7	29	0.100	0.020	4.88	0.00037
max_set	Translation (Information)	34	89	0.224	0.063	3.56	E-12
	Nucleotide m/tr (Metabolism)	8	29	0.053	0.020	2.57	0.0083

We evaluated which of 49 sub-categories are enriched by the min_set or the max_set. In the table, sample means the min_set (70 FSFs) or max_set (152 FSFs). The 1,416 FSFs represent the background (bkgd). For convenience, let us assume that M and k represent the number of FSFs that are assigned to a particular sub-category in the background (extant FSFs) and sample (urncestral FSFs) and N and n are the total numbers of FSFs in the background and sample without functional categorizations. The rates for the sample and the background are notated by k/n and M/N, respectively. The ratio was determined by dividing the sample rate by the background rate. The P values were calculated using the hypergeometric distribution. The enrichment of the sub-categories that are listed was supported at the 95% confidence level.