Table 4. Nested analysis of molecular variance (AMOVA) of 329 individuals in 15 populations of Solanum rostratum in three geographic regions: Mexico, the USA, and China.

Source of variation	d.f.	Sum of squares	Variance components	% variation	P-value
Among regions	2	243.72	0.471	16.25	<0.001
Among populations within regions	12	231.72	0.394	13.59	<0.001
Within populations	643	1309.19	2.036	70.17	<0.001
Total	657	1784.64	2.901

P-values were calculated using 1023 permutations, under the null hypothesis that a given variance component is equal to zero.