Appendix B. A global model predicting log-transformed bird species richness.
A global model predicting log-transformed bird species richness for continental samples and islands around the world (n = 586). The three retained terms are listed in order of inclusion by forward selections with cumulative R2 values. Increase in R2 and P values of excluded terms are also shown if they where to be included as a fourth term. Note that these results are very similar to the results shown in Fig. 3, in which richness 0.3 is the dependent variable. Tests of the residuals for homoscedasticity show that the residuals using log-transformed richness are strongly non-normal (P < 10-10), whereas residuals using richness 0.3 are normal (P = 0.29).
Cumulative R2 |
P |
|
Retained terms: |
||
Distance to continent0.2 |
0.534 |
<10-15 |
Log area × precipitation0.4 |
0.749 |
<10-15 |
Temperature |
0.803 |
<10-15 |
Excluded terms: |
||
Faunal region (7 levels)† |
+ 0.062§ |
<10-10 |
Sample category (continental or insular)† |
+ 0.018 |
<10-10 |
Geohistory (continental, landbridge, oceanic)† |
+ 0.019 |
<10-10 |
Distance to continent0.2 × neighbor index |
+ 0.033 |
<10-15 |
Distance to continent0.2 × log area |
+ 0.011 |
<10-7 |
Elevation rang0.4 ‡ |
} + 0.012 |
<10-4 |
Elevation range0.4 × temperature ‡ |
<10-8 |
|
Temperature × precipitation0.4 ‡ |
} + 0.012 |
<10-7 |
Temperature × (precipitation0.4)² ‡ |
<10-8 |
† Categorical variable
‡ Two terms included simultaneously
§ This term would be retained in this model (cf. Table 3)