Table 1.

Divergence and GC content values for intronic sequences. Introns were divided into two classes based on their average intron length (232 bp): short introns, ≤232 bp; long introns, >232 bp. Divergence values (K_i) are means across introns (standard errors are in parenthesis). Results of Wilcoxon two-sample test (P) between short and long intron (in column) and first and non-first intron (in line) are shown.

Introns	Divergence				GC Content
	All	Short intron	Long intron	P	All	Short intron	Long intron	P
All		0.089 (0.006)	0.050 (0.005)	0.033		0.347 (0.003)	0.352 (0.003)	0.264
First	0.079 (0.012)	0.110 (0.018)	0.037 (0.006)	0.001	0.394(0.007)	0.396 (0.010)	0.391 (0.009)	0.705
Non-first	0.078 (0.005)	0.086 (0.006)	0.055 (0.006)	0.259	0.340 (0.002)	0.339(0.003)	0.341 (0.003)	0.544
P	0.4579	0.050	0.291		0.000	0.000	0.000