We study a system of interacting diffusions
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indexed by the hierarchical group $\Xi$, as a
genealogical two genotype model [where $x _\xi(t)$ denotes the frequency of,
say, type A] with hierarchically determined degrees of relationship between
colonies. In the case of short interaction range it is known that the system
clusters. That is, locally one genotype dies out. We focus on the description
of the different regimes of cluster growth which is shown to depend on the
interaction kernel $a(\dot,\dot)$ via its recurrent potential kernel. One of
these regimes will be further investigated by mean-field methods. For general
interaction range we shall also relate the behavior of large finite systems,
indexed by finite subsets $\Xi_n$ of, $\Xi$ to that of the infinite system. On
the way we will establish relations between hitting times of random walks and
their potentials.