Table 1. The most interesting statements and their truth values according the goalkeeper-model and the lock-key-model.

	Statement	goalkeeper	lock-key
A	If only in the ovum but not in the sperm, Wolbachia does not cause CI	true	true
B	Bidirectional incompatibility is possible	true	true
C	Unidirectional incompatibility is possible	true	true
D	Additional strains in males cannot decrease mod strength	true	true
D′	Even if strain rescues strain , it cannot rescue the double-infection (except if is [mod−])	true	false
D″	If strain rescues strain , it also rescues the double-infection	false	true
E	Additional strains in females cannot decrease resc strength	true	true
E′	The double-infection rescues the mono-infection	true	true
F	The existence of [mod− resc+] strains is possible	true	true
H	There are strains and that cannot rescue by themselves but can do so together	true	true
I	Intransitivity: It is possible that rescues which rescues , but still cannot rescue	true	true
J	If rescues the double-infection , then the double infection rescues the triple-infection	false	true
K	Only if rescues does the double-infection rescue the double-infection	true	false
M	There are strains that are [mod−] in one host and [mod+] in another	true	not derivable
P	If rescues , and if rescues , it also rescues the double-infection	false	true

Evidence: A: [28, and many others], B: [28], [37], C: [16], [17], [19], [38], D: [16], [23], [38], [39], E: [16], [22], [23], [38], E′: [16], [22], F: [35], [40], I: [17], [19], M: [19], [35]. Formal proofs: Text S1.

Statements A-F are from [14]. It is assumed that each strain can rescue itself.