Table 1. Effects of population and herbivore removal on damage from herbivores and fitness components in three Lythrum salicaria populations in the year of the experimental treatment (2013).

Flowering status (flowering vs. not flowering) was analysed with a generalized linear model (χ2 given); the other response variables were analysed with ANOVA (F-ratios given). The effect of herbivore removal was analysed separately by population with contrasts when a significant population × treatment interaction was detected. Significant effects are in bold.

					Forsmark		Vitskärsudden		Skagsudden
Response variable	Source of variation	df	F / χ2	P	t	P	t	P	t	P
Proportion of leaf area removed	Population	2,580	101.75	<0.0001
	Herbivore removal	1,580	327.62	<0.0001	18.1	<0.0001	7.18	<0.0001	9.49	<0.0001
	Pop × Herb rem	2,580	33.78	<0.0001
Early-season plant height	Population	2,593	22.76	<0.0001
	Herbivore removal	1,593	0.0005	0.98
	Pop × Herb rem	2,593	0.37	0.69
Late-season plant height	Population	2,583	46.96	<0.0001
	Herbivore removal	1,583	40.07	<0.0001	-6.33	<0.0001	-3.10	<0.0001	1.18	0.24
	Pop × Herb rem	2,583	14.32	<0.0001
Flowering status	Population	2,586	93.64	<0.0001
	Herbivore removal	1,585	64.85	<0.0001	-7.58	<0.0001	-4.50	<0.0001	0.38	0.71
	Pop × Herb rem	2,584	29.13	<0.0001
# flowers per reproductive plant	Population	2,340	3.45	0.03
	Herbivore removal	1,340	9.93	0.002	-3.15	0.002	-1.14	0.26	-0.60	0.55
	Pop × Herb rem	2,340	3.14	0.04
# seeds per flower	Population	2,339	3.95	0.02
	Herbivore removal	1,339	8.90	0.003	-2.98	0.003	-2.12	0.04	0.66	0.51
	Pop × Herb rem	2,339	5.31	0.005
# fruits per plant	Population	2,583	56.88	<0.0001
	Herbivore removal	1,583	141.16	<0.0001	-11.88	<0.0001	-4.85	<0.0001	-0.64	0.52
	Pop × Herb rem	2,583	32.65	<0.0001
# seeds per plant	Population	2,583	69.03	<0.0001
	Herbivore removal	1,583	128.25	<0.0001	-11.32	<0.0001	-5.52	<0.0001	0.07	0.95
	Pop × Herb rem	2,583	32.85	<0.0001