But the vehicle is not something fundamental, in terms of which other explanations should be framed. The cooperative crickets, sculling like Mole and Ratty in unison towards their lily pad, are enchanting. But it is deeply unhelpful to claim that the pair is the vehicle of selection. There is no vehicle of selection in this case. It is a terrific vehicle-undermining example.
Natural selection favours replicators that prosper in their environment.
The environment of a replicator includes the outside world but it also includes, most importantly, other replicators, other genes in the same organism and in different organisms, and their phenotypic products. Cricket genes for cooperating in the presence of another cooperating cricket prosper. This statement is true and illuminating, in precisely the same sense as the statement that genes for thick hairy coats prosper in the presence of snow. Like snow, each cricket is part of the environment of the other one's genes. It would be unfair to accuse Wilson and Sober of including the snow as part of that which is selected, although it would follow from my view of the world that that is what they are, in effect, doing.