Table 3. Analysis of molecular variance (AMOVA) for nuclear microsatellite and plastid DNA data at three hierarchical levels.

	Microsatellites					Plastid DNA
	d.f.	Sum of squares	Variation (%)	F-statistic	P	d.f.	Sum of squares	Variation (%)	F-statistic	P
Between species	1	242.17	42.34	FCT = 0.423	<0.001	1	485.168	55.75	FCT = 0.558	<0.001
Among populations within species	5	48.631	4.81	FCS = 0.083	<0.001	5	123.549	8.5	FCS = 0.192	<0.001
Within populations	299	585.385	52.86	FST = 0.471	0.025	142	579.122	35.75	FST = 0.643	0.026

Variance analysis only included the four pure Populus alba and three pure P. tremula populations.