Table 2 Results of the multiple linear regression models of the syllable repertoire (first 3 PC of the Principal component analysis) on predictor variables (volume of 3 vocal control nuclei with whole body mass as co-variate), including for each predictor the estimate and associated probability

− 2.151 (4.903)

− 0.44

0.674

8.637 (6.93)

1.25

0.281

6.024 (10.236)

0.59

0.575

16.259 (15.435)

1.05

0.352

4.131 (3.815)

1.08

0.315

2.679 (5.234)

0.51

0.636

0.151 (0.135)

1.11

0.302

0.315 (0.249)

1.26

0.275

− 4.807 (3.494)

− 1.38

0.211

− 12.156 (5.818)

− 2.09

0.105

0.064 (7.588)

0.01

0.993

16.6 (6.401)

2.59

0.06

5.472 (15.842)

0.35

0.74

4.154 (14.256)

0.29

0.785

− 1.051 (5.905)

− 0.18

0.864

− 0.654 (4.835)

− 0.14

0.899

− 0.073 (0.21)

− 0.35

0.737

0.072 (0.23)

0.31

0.772

0.439 (5.408)

0.08

0.938

− 5.047 (5.374)

− 0.94

0.401

2.811 (3.266)

0.86

0.418

− 2.87 (4.837)

− 0.59

0.585

− 0.097 (6.819)

− 0.01

0.989

9.204 (10.772)

0.85

0.441

5.32 (2.541)

2.09

0.075

3.011 (3.653)

0.82

0.456

− 0.285 (0.09)

− 3.16

0.016*

− 0.142 (0.174)

− 0.81

0.461

1.986 (2.328)

0.85

0.422

1.427 (4.06)

0.35

0.743