Table 1.
Least squares regression statistics (±95%CL) for the scaling equations of snake morphology.
| Variables | Burmese python (n = 43) | Brown treesnake (n = 19) | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| ind | dep | exp | obs | slope | intercept | R 2 | obs | slope | intercept | R 2 |
| SVL | mass | 3 | + | 3.260 ± 0.151 | −3.847 ± 0.349 | 0.979 | + | 3.398 ± 0.283 | −4.684 ± 0.560 | 0.974 |
| SVL | Gdiam | 1 | − | 0.870 ± 0.067 | −1.055 ± 0.154 | 0.944 | = | 1.009 ± 0.113 | −1.608 ± 0.225 | 0.954 |
| SVL | Garea | 2 | − | 1.739 ± 0.134 | −2.215 ± 0.308 | 0.944 | = | 2.017 ± 0.227 | −3.320 ± 0.449 | 0.954 |
| SVL | SKL | 1 | − | 0.732 ± 0.036 | −0.942 ± 0.084 | 0.976 | − | 0.668 ± 0.069 | −0.983 ± 0.136 | 0.961 |
| SVL | SKW | 1 | − | 0.783 ± 0.079 | −1.475 ± 0.181 | 0.908 | − | 0.753 ± 0.136 | −1.511 ± 0.270 | 0.889 |
| SVL | QL | 1 | − | 0.735 ± 0.038 | −1.509 ± 0.088 | 0.973 | + | 1.192 ± 0.067 | −2.364 ± 0.132 | 0.988 |
| SVL | LJDL | 1 | − | 0.750 ± 0.042 | −0.925 ± 0.096 | 0.970 | − | 0.891 ± 0.070 | −1.354 ± 0.138 | 0.977 |
| SKL | Garea | 2 | + | 2.366 ± 0.155 | 0.030 ± 1.117 | 0.959 | + | 3.000 ± 0.215 | −0.348 ± 0.077 | 0.981 |
| ALL | Garea | 2 | + | 2.304 ± 0.141 | −1.094 ± 1.178 | 0.963 | = | 2.142 ± 0.176 | −1.273 ± 0.162 | 0.975 |
| mass | Garea | 0.67 | − | 0.531 ± 0.036 | −0.155 ± 0.132 | 0.957 | − | 0.588 ± 0.061 | −0.529 ± 0.130 | 0.961 |
| mass | SKL | 0.33 | − | 0.222 ± 0.011 | −0.070 ± 0.040 | 0.977 | − | 0.196 ± 0.014 | −0.060 ± 0.030 | 0.980 |
| SKL | QL | 1 | = | 0.998 ± 0.036 | −0.561 ± 0.027 | 0.987 | + | 1.730 ± 0.163 | −0.593 ± 0.059 | 0.967 |
| SKL | LJDL | 1 | = | 1.022 ± 0.037 | 0.043 ± 0.028 | 0.987 | + | 1.318 ± 0.059 | −0.038 ± 0.021 | 0.992 |
| SKW | QL | 1 | − | 0.871 ± 0.075 | −0.104 ± 0.028 | 0.931 | + | 1.425 ± 0.243 | 0.024 ± 0.040 | 0.900 |
| SKW | LJDL | 1 | − | 0.892 ± 0.075 | 0.509 ± 0.028 | 0.934 | = | 1.082 ± 0.165 | 0.432 ± 0.027 | 0.919 |
Independent and dependent variables are indicated by ind and dep, respectively. The slopes expected from geometric similarity are indicated by exp. Observed slopes (obs) that conformed to isometry (based on 95% CL) or had negative or positive allometry are indicated by = ,− and +, respectively. All P-values for the test of the overall significance of the regression (slope not equal to 0) were less than 10–8. Abbreviations: SVL, snout-vent length; Gdiam, maximal gape diameter; Garea, maximal gape area; SKL, skull length; SKW skull width; QL quadrate length; LJDL length of the entire lower jaw; ALL = SKW + 2QL + 2LJDL. Units of distance, area and mass are cm, cm2 and g, respectively, and all values were log10 transformed. If the slopes differed significantly between the two species in an ANCOVA (with the independent variable as the covariate), bold typeface indicates the slope of the species with a greater value. If the slopes were homogenous, then the species with the significantly greater mean adjusted for the covariate is indicated by boldface type for its intercept. See Table S2 for ANCOVA results.