Appendix D. Logistic regression results for the effect of phylogenetic distance (My), joint relative abundance (JRA), or the interaction (MyxJRA) on the probability that two plant species shared epifoliar fungal symbionts, from radial transects at San Lorenzo, Panama and Cape Tribulation, Australia.
Akaike Information Criterion (AIC), Likelihood Ratio (LR), P values of Wald test chisquare estimates for each factor, and percent concordance were used to select the best model for each site. At neither site did phylogenetic distance between plant species pairs contribute significantly to the model. Intercept was always significant (P ≤ 0.004 for all).
P values 

Site 
Model 
AIC 
LR 
LR 
My 
JRA 
MyxJRA 
Conc.% 
SanLorenzo  1 
787.4  18.7  0.0003  0.5426  0.0067  0.0532  61.4 
SanLorenzo  2 
789.3  14.8  0.0006  0.6816  0.0001  60.8 

SanLorenzo  3 
802  0.1  0.8379  0.8374  23.3 

SanLorenzo  4 
787.4  14.67  0.0001  0.0001  60.4 

SanLorenzo  5 
762.7  39.4  0.0001  0.0001†  63.3 

CapeTrib  1 
796  27.2  0.0001  0.5328  0.1944  0.9277  63.6 
CapeTrib  2 
794  27.2  0.0001  0.4079  0.0001  63.7 

CapeTrib  3 
818.3  0.9  0.3407  0.3293  34.8 

CapeTrib  4 
792.7  26.6  0.0001  0.0001  62.7 

CapeTrib  5 
754.7  64.5  0.0001  0.0001†  71.4 
†Model uses log10(joint relative abundance).
At both sites, model 5 was the best, taking the form p(sharing) = expy / (1 + expy) where:
y = 2.0995 + 1.2722 log10JRA (for San Lorenzo)
y = 1.7059 + 1.1563 log10JRA (for Cape Tribulation).
To compare the logistic model predictions to the rates of fungal sharing observed at each site (Fig. 1), we grouped all pairwise joint relative abundances into logseries bins with lower bounds at 0.5x. In each bin, we calculated the proportion of plant pairs that shared fungal taxa.
San Lorenzo, Panama 
Cape Tribulation, Australia 

x 
Lower bound 
No. shared pairs 
No. total pairs 
Proportion shared 
No. shared pairs 
No. total pairs 
Proportion shared 
19 
1.91E06 
0 
0 
0 
55 
2.85E06 

18 
3.82E06 
0 
0 
0 
110 
5.71E06 

17 
7.63E06 
0 
0 
1 
133 
3.42E05 

16 
1.53E05 
6 
351 
0.0171 
10 
255 
0.0001 
15 
3.05E05 
0 
0 
9 
311 
0.0005 

14 
6.10E05 
11 
216 
0.0509 
9 
271 
0.0014 
13 
1.22E04 
42 
683 
0.0615 
28 
254 
0.0048 
12 
2.44E04 
17 
206 
0.0825 
14 
199 
0.0127 
11 
4.88E04 
20 
130 
0.1538 
13 
121 
0.0308 
10 
9.77E04 
8 
50 
0.1600 
13 
76 
0.0455 
9 
1.95E03 
4 
13 
0.3077 
6 
33 
0.0634 
8 
3.91E03 
0 
3 
0.0000 
4 
10 
0.0395 
7 
7.81E03 
0 
1 
0.0000 
0 
2 
0.0174 