Table 6.

Survey of environmental variables that are best correlated with occurrence of ploidy levels in constrained principal coordinates analysis applied to environmental variables recorded in populations of Allium oleraceum in the Czech Republic

4x (+) vs. 5x (−)	r	4x (+) vs. 6x (−)	r	5x (+) vs. 6x (−)	r
Forest	0·68	Habitat naturalness	0·65	Habitat naturalness	0·57
Habitat naturalness	0·65	Forest	0·64	Soil Ca2+	0·54
Colder climate	−0·28	Light conditions	−0·55	Colder climate	−0·49
Light conditions	−0·42	Soil Ca2+	0·26	pH	0·42
Arable field & field margin	−0·57	Arable field & field margin	−0·58	Arable field & field margin	−0·52
Presence of arable land	−0·66	Presence of arable land	−0·75	Presence of arable land	−0·67

Within each analysis, variables showing the highest positive or negative correlations with the first canonical axis are reported together with their sign and correlation coefficient. The sign of correlation coefficients corresponds to the position of the respective ploidy level along the first canonical axis within each analysis (i.e. 4x vs. 5x; 4x vs. 6x; 5x vs. 6x). For explanations of variables see Methods.