Phylogenomic analysis of natural selection pressure in Streptococcus genomes

Table 3 Odds of positive selection in gene clusters categorised according to COG-derived functional assignments

	Odds of positive selection			Pathogen verses core clusters
	All clusters	Pathogen-specific clusters	Core-gene clusters	Odds ratio	P -value
Information storage & processing	0.07	0.05	0.08	0.61	0.565
Cellular processes & signalling	0.10	0.10	0.10	1.04	1
Metabolism	0.08	0.04	0.12	0.35	0.02158
Gene with inadequately characterised function	0.05	0.07	0.02	2.92	0.2802
Not in the COG database	0.08	0.08	0.00	Infinite	1
Genes with multiple COG functions	0.07	0.06	0.09	0.68	1

Notes: The odds of positive selection were computed as the relative frequently of genes under positive selection divided by the relative frequency of genes not under positive selection. The odds ratio is simply the ratio of the odds of positive selection in two different categories of genes. The categories were based on functional assignments found in the COG database. The hypothesis that an odds ratio differed from one was tested by using the Fisher's exact test.

ISSN: 2730-7182