Table 2.

Generalized linear mixed model of embryonic survival.

Random effects	Variance ± SE		Z	P
Family (Pond pH)	35.77 ± 14.78		2.42	0.008
Family (Pond pH) × pH treatment	80.88 ± 14.22		5.69	< 0.001
Fixed effects	ndf	ddf	F	P
Pond pH	7	60.8	1.2	0.319
pH treatment	2	127.4	430.6	< 0.001
Pond pH × pH treatment	14	120.2	2.7	0.002
Block	2	546.0	11.3	< 0.001
Linear contrasts	ndf	ddf	F	P
Pond pH	1	61.3	1.3	0.256
Pond pH × pH treatment (4.0 vs. 4.3)	1	85.6	10.6	0.002
Pond pH × pH treatment (4.0 vs. 7.5)	1	179.1	24.0	< 0.001
Pond pH × pH treatment (4.3 vs. 7.5)	1	174.2	5.2	0.024

Results are shown for eight R. arvalis populations occurring along a pH gradient. Significant effects are highlighted in bold