Table 2.

Mixed model analysis of latitudinal clines and phenotypic differences between native and introduced plant populations of 34 species from 47 common garden studies, based on four principal components (PCs) combining all phenotypic traits (All traits), and those related to size, reproduction, or defense

	All traits			Size			Reproduction			Defense
Fixed effect	d.f.	F	P-value	d.f.	F	P-value	d.f.	F	P-value	d.f.	F	P-value
Latitude	1, 852	1.8	0.186	1, 906	0.2	0.638	1, 603	3.1	0.079	1, 311	0.2	0.656
Range	1, 56	3.3	0.076	1, 54	0.9	0.343	1, 24	6.9	0.015	1, 311	0.0	0.934
Taxonomic group	1, 852	0.0	0.848	1, 906	0.0	0.977
Range*group	1, 852	2.9	0.088	1, 906	1.5	0.215
Latitude*range	1, 852	8.3	0.004	1, 906	4.5	0.035	1, 603	6.4	0.012	1, 311	0.0	0.930

Entries in bold indicate statistically significant results.

Fixed factors in the model include population range (native or introduced) and taxonomic group (monocotyledon or dicotyledon), with latitude as a continuous covariate. Also shown are degrees of freedom (d.f.), F-values and significance (P). The random effect range^*species was significant (P < 0.001) for all traits except defense (P = 0.281). The effect of range^*garden was significant for the PC of ‘All traits’ only (P = 0.009). Range^*family, latitude^*garden, and latitude^*species were not significant for any of the PC measurements (P > 0.357).