Table 1.

A linear multiple regression analysis of contrasts relating extra-pair paternity (square root-arcsine-transformed) to the proportion of polymorphic loci (square root-arcsine-transformed), sexual dichromatism, body mass (log-transformed), and sample size (log-transformed)

Variable	Coefficient	SE	t	P
Polymorphic loci	1.952	0.203	9.61	<0.0001
Dichromatism	0.255	0.027	9.29	<0.0001
Body mass	−0.400	0.054	−7.38	<0.0001
Sample size	0.090	0.021	4.27	0.0002
Polymorphic loci ∗ dichromatism	−0.587	0.092	−6.41	<0.0001

The regression model has the following statistics F = 31.01; d.f. = 5, 26; r² = 0.85; P < 0.0001. The model includes the only interaction term that explained a significant amount of the variation.