Table 2.

Promoter evolution and relative testes size. (Statistical values of linear regression models between the genetic divergence of the regulatory elements of protamines and relative testes size. Note that, irrespective of the way in which the relative divergence of Prm 2 promoter in relation to Prm 1 promoter and/or INT sequences is analysed, all the variables considering the promoter region of Prm 2 fit a linear regression model with statistical confidence (p<0.05). Genetic divergence of the Prm 1 promoter, Prm 2 promoter and INT sequences was estimated as the mean distribution value of branch lengths computed after a 10 000 bootstrap-based analysis (see fig. S3 in the electronic supplementary material). n.s., non-significant at 95% of statistical confidence. ^*Significant at 95% of statistical confidence. ^**Significant at 99% of statistical confidence. ^***Significant at 99.9% of statistical confidence.)

variable	R2	p-value
INT	−0.0957	0.5662n.s.
Prm 1 promoter	−0.0434	0.4322n.s.
Prm 1 promoter/INT	−0.1631	0.8960n.s.
Prm 2 promoter	0.7065	0.0055**
Prm 2 promoter/INT	0.5826	0.0168*
Prm 2 promoter−Prm 1 promoter	0.8091	0.0014**
(Prm 2 promoter−Prm 1 promoter)/INT	0.8599	0.0005***
Prm 2 promoter/Prm 1 promoter	0.8233	0.0011**
(Prm 2 promoter−INT)/(Prm 1 promoter−INT)	0.5619	0.0195**