ELECTRONIC SUPPLEMENTARY MATERIAL III.
The effect of different forms of the trade-off relationships.
(i) A different form of the relationship between pathogen aggressiveness, x, and horizontal
transmission rate parameter (x).
We replace the linear relation as used in the default model by the relation
x
 ( x) 
1  x
Using model equations (1) and the trade-off relationships for (x) and g(x) as used to construct Fig.
4, as well as the parameter values used to construct Fig. 4, we find for a parameter value for =0.4,
Figure ESM III.1.
Figure ESM III.1
(ii) A different form of the relationship between pathogen aggressiveness, x, and the pathogen
induced host death rate (x).
We replace the relation as used in the default model by the relation
( x)    exp(s x) 1
Using model equations (1) and the trade-off relationships for (x) and g(x) as used to construct Fig.
4, as well as the parameter values used to construct Fig. 4, we find for a parameter value for =0.01
and s=0.5, Figure III.2.
Figure ESM III.2
(iii) A different form of the relationship between pathogen aggressiveness, x, and the probability of
seed out-selection g(x).
We replace the relation as used in the default model by the relation
a x  xlim
xlim x  a
Using model equations (1) and the trade-off relationships for (x) and g(x) as used to construct Fig.
4, as well as the parameter values used to construct Fig. 4, we find for a parameter value for a=7,
xlim=xmax exp(-b), xmax=5 and b=250 Figure ESM III.3.
g ( x) 
Figure ESM III.3