Table 2.

Outputs and significance of the final linear mixed models testing the differences in mean δ ¹³C and trophic position (TP) between the species across the mesocosm experiment, where mesocosm was the random effect on the intercept

Final model structure (and result):
δ 13C ~ species × experimental treatment (AIC = 141.8; log likelihood = −64.9; P < 0.01)
Trophic position ~ species × experimental treatment (AIC = −178.9; log likelihood = 95.4; P < 0.01)
Pairwise comparison		Mean difference in δ 13C	Mean difference in TP
Allopatric	Allopatric Squalius cephalus	2.12 ± 0.36, P < 0.01*	0.13 ± 0.03, P < 0.01*
B. barbus	Sympatric with S. cephalus	0.85 ± 0.36, P > 0.1	0.11 ± 0.03, P = 0.01*
Allopatric	Sympatric with B. barbus	0.36 ± 0.36, P > 0.1	0.02 ± 0.03, P > 0.1
S. cephalus
B. barbus in sympatry with S. cephalus		1.63 ± 0.23, P < 0.01*	0.004 ± 0.02, P > 0.1

Mean differences are from estimated marginal means (* = difference significant at P < 0.05).