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Table 2 Summary results from general linear mixed models testing for differences in head morphology (overall head shape extracted from a principal component analysis, gillraker number and gillraker length) between threespine sticklebacks from marine and the freshwater habitats

From: The temporal window of ecological adaptation in postglacial lakes: a comparison of head morphology, trophic position and habitat use in Norwegian threespine stickleback populations

Test

Source

DF

Estimate ± SE

F

P

Head shape (PC1)

Intercept

 

0.019 ± 0.008

 

0.021

R2 = 0.62

Habitat (marine vs freshwater)

1

−0.017 ± 0.006

8.07

0.009

N fish = 504

Sex

1

0.004 ± 0.000

55.22

< 0.001

N populations = 26

Total length (cm)

1

−0.001 ± 0.001

0.89

0.345

Head shape (PC2)

Intercept

 

0.024 ± 0.005

 

< 0.001

R2 = 0.63

Habitat (marine vs freshwater)

1

0.016 ± 0.003

38.06

< 0.001

N fish = 504

Sex

1

0.005 ± 0.000

126.20

< 0.001

N populations = 26

Total length (cm)

1

−0.009 ± 0.001

95.62

< 0.001

Head shape (PC3)

Intercept

 

−0.014 ± 0.006

 

0.027

R2 = 0.25

Habitat (marine vs freshwater)

1

−0.006 ± 0.002

4.78

0.038

N fish = 504

Sex

1

0.003 ± 0.001

28.92

< 0.001

N populations = 26

Total length (cm)

1

0.004 ± 0.001

12.30

0.005

Head shape (PC4)

Intercept

 

−0.027 ± 0.006

 

< 0.001

R2 = 0.37

Habitat (marine vs freshwater)

1

0.005 ± 0.003

2.24

0.147

N fish = 504

Sex

1

−0.001 ± 0.001

1.47

0.227

N populations = 26

Total length (cm)

1

0.006 ± 0.001

26.92

< 0.001

Gillraker number

Intercept

 

18.897 ± 0.683

 

< 0.001

R2 = 0.29

Habitat (marine vs freshwater)

1

−0.078 ± 0.374

0.04

0.836

N fish = 503

Sex

1

−0.185 ± 0.058

10.17

0.002

N populations = 26

Total length (cm)

1

0.048 ± 0.119

0.16

0.686

Gillraker length

Intercept

 

0.380 ± 0.060

 

< 0.001

R2 = 0.61

Habitat

1

−0.177 ± 0.028

35.85

< 0.001

N fish = 503

Sex

1

−0.043 ± 0.005

62.71

< 0.001

N populations = 26

Total length (cm)

1

0.137 ± 0.011

155.21

< 0.001

  1. Total length (cm) and sex used as covariates. Lake identity was used as a random variable