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Table 1 The structure of Generalized Linear Models used to investigate the effects of sex, size (carapace length, CL mm) and infestation intensity on the number of avoiding, retreating, threatening and fighting behaviours performed by Xironogiton victoriensis (Annelida: Clitellata) infested signal crayfish (Pacifastacus leniusculus)

From: Reduced aggression and foraging efficiency of invasive signal crayfish (Pacifastacus leniusculus) infested with non-native branchiobdellidans (Annelida: Clitellata)

Dependent variable

Independent variables

Significant terms

Deviance

Df

P

No. of avoid behaviours

Sex, Size (CL mm), Infestation Intensity, Total Behaviours

Sex

129.54

1,24

<0.01

Size (CL mm)

116.20

1,24

0.03

Total Behaviours

212.15

1,24

<0.0001

Sex, Size (CL mm), Total Behaviours

Sex

129.54

1,24

<0.01

Size (CL mm)

116.20

1,24

0.03

Total Behaviours

212.15

1,24

<0.0001

Sex, Infestation Intensity, Total Behaviours

Sex

119.80

1,24

0.03

Infestation Intensity

116.20

1,24

0.05

Total Behaviours

195.88

1,24

<0.0001

No. of retreat behaviours

Sex, Size (CL mm), Infestation Intensity, Total Behaviours

Total Behaviours

219.89

1,26

<0.0001

Sex, Size (CL mm), Total Behaviours

Total Behaviours

219.89

1,26

<0.0001

Sex, Infestation Intensity, Total Behaviours

Total Behaviours

219.89

1,26

<0.0001

No. of threat behaviours

Sex, Size (CL mm), Infestation Intensity, Total Behaviours

Infestation Intensity

200.31

1,25

<0.01

Sex, Size (CL mm), Total Behaviours

Sex

200.31

1,25

0.05

Sex, Infestation Intensity, Total Behaviours

Infestation Intensity

200.31

1,25

<0.01

No. of fight behaviours

Sex, Size (CL mm), Infestation Intensity, Total Behaviours

Nothing

N/A

N/A

N/A

Sex, Size (CL mm), Total Behaviours

Nothing

N/A

N/A

N/A

Sex, Infestation Intensity, Total Behaviours

Nothing

N/A

N/A

N/A

  1. For significant terms (P ≤ 0.05) the deviance, degrees of freedom (df) and P-values are reported. In each model, the total number of all types of behaviours performed by crayfish was also included as a controlling variable, which was retained in the final refined models (after stepwise deletions of non-significant terms based on Analysis of Variance) even if not significant