  In social situations with which evolutionary game is concerned, individuals
are considered to be heterogeneous in various aspects. In particular, they may
differently perceive the same outcome of the game owing to heterogeneity in
idiosyncratic preferences, fighting abilities, and positions in a social
network. In such a population, an individual may imitate successful and similar
others, where similarity refers to that in the idiosyncratic fitness function.
I propose an evolutionary game model with two subpopulations on the basis of
multipopulation replicator dynamics to describe such a situation. In the
proposed model, pairs of players are involved in a two-person game as a
well-mixed population, and imitation occurs within subpopulations in each of
which players have the same payoff matrix. It is shown that the model does not
allow any internal equilibrium such that the dynamics differs from that of
other related models such as the bimatrix game. In particular, even a slight
difference in the payoff matrix in the two subpopulations can make the opposite
strategies to be stably selected in the two subpopulations in the snowdrift and
coordination games.
