Table 1.

Hierarchical F_ST analyses (AMOVA) of sympatric ecotypes by region.

		Number of		Variance component			Fixation indices (and probability of H0)
Hierarchical structure	Region*	units†	samples‡	Within samples	Among samples within unit	Among units	Samples (Fst)	Units (Fct)
Ecotypes within site (site is unit)	Northern	4	18	0.271	0.030	0.018	0.15 (<0.001)	0.06 (<0.06)
	Coastal	4	12	0.177	0.083	0.133	0.55 (<0.001)	0.34 (<0.01)
	Southern	9	20	0.264	0.032	0.023	0.17 (<0.001)	0.07 (0.02)
Sites within ecotype (ecotype is unit)	Northern	3	18	0.271	0.042	0.006	0.15 (<0.001)	0.02 (0.16)
	Coastal	3	12	0.177	0.194	−0.009	0.51 (<0.001)	−0.02 (0.63)
	Southern	2	20	0.264	0.056	−0.006	0.16 (<0.001)	−0.02 (0.84)

Bold font indicates that the fixation index is statistically > 0.

^*Regions putatively colonized from different glacial refuges (Wood 1995, Wood et al. unpublished data).

^†Units are defined as either sites or ecotypes (see column 1).

^‡Samples refer to the individual populations in Supplementary Table 1.