Natural selection drives rapid evolution of mouse embryonic heart enhancers

BMC Systems Biology

Table 1 The proportions of enhancers that underwent selection based on mouse-rat alignments (neutral reference: fourfold degenerate sites)

	Total	Under selection^a	Positively selected^b	Under selection^a/Total	Positively selected^b/Under selection^a	Positively selected^b/Total
HT	2554	875	360	34.25%	41.14%	14.09%
FB	1253	595	67	47.48%	11.26%	5.34%
MB	1311	521	101	39.74%	19.38%	7.70%
LB	2570	1037	212	40.35%	20.44%	8.24%

FB: forebrain; MB: midbrain; LB: limb; HT: heart.
^aA significantly unequal proportion of substituted sites were observed between enhancers and the fourfold degenerate sites of the neighboring gene by Fisher's exact test.
^bEnhancers that underwent selection and had a higher substitution rate than the fourfold degenerate sites of the neighboring gene.

ISSN: 1752-0509