Small-scale phenotypic differentiation along complex stream gradients in a non-native amphipod

Table 2 Results of a factor reduction procedure (PCA) on 11 environmental parameters measured at our 16 sampling sites

	Env. PC 1	Env. PC 2	Env. PC 3	Env. PC 4
Stream width [m]	0.89	−0.15	− 0.01	− 0.02
Stream depth [m]	0.79	−0.32	0.22	−0.04
Water temperature [°C]	0.39	0.01	0.58	0.49
Oxygen content [mg L⁻¹]	0.23	0.10	−0.85	0.20
Flow velocity [m s⁻¹]	0.06	0.59	0.01	−0.19
Conductivity [μS cm⁻¹]	0.80	0.27	−0.21	0.14
Density (catch-per-unit effort)	0.20	0.61	0.40	0.23
Altitude [m]	−0.83	−0.16	0.15	0.05
Sex ratio (females/ males)	−0.06	0.77	−0.24	0.01
Thermal pollution (yes/ no)	0.79	0.22	0.14	0.11
Season (summer/ winter)	−0.04	−0.10	−0.10	0.93

Shown are PC axes (‘environmental PCs’) with eigenvalues > 1.0; axes were varimax-rotated using the Kaiser Normalization method. Variables with |axis loading| ≥ 0.5 are highlighted in bold font

ISSN: 1742-9994