Group selection, individual selection, and the evolution of genetic drift.

In a subdivided population, genetic drift affects variation between groups, and thus it can have an important effect on the outcome of evolution (Wright, 1978). The rate of genetic drift is determined, in part, by the behaviour of population members. This paper presents three mathematical models in which behavioural traits that affect the rate of genetic drift are allowed to coevolve with traits that are under selection at the group and individual levels. The results show that if group selection is strong relative to individual selection, then behavioural traits that enhance the rate of genetic drift will tend to increase in frequency. The strength of this effect depends, in part, on the way in which vacant sites are colonized.