I am confused as to how to compute the effective population size $N_e$ of a theoretical structured population. Let's consider here a simple case study.
Imagine a 2-deme metapopulation. Each deme is of constant size $N$ with a (forward and backward) migration rate $m$. Mating is random within each deme.
What is the effective population size of such population? In other words, how fast does the population loses heterozygosity through time?