  We study the evolution of the network properties of a populated network
embedded in a genotype space characterised by either a low or a high number of
potential links, with particular emphasis on the connectivity and clustering.
Evolution produces two distinct types of network. When a specific genotype is
only able to influence a few other genotypes, the ecology consists of separate
non-interacting clusters in genotype space. When different types may influence
a large number of other sites, the network becomes one large interconnected
cluster. The distribution of interaction strengths -- but not the number of
connections -- changes significantly with time. We find that the species
abundance is only realistic for a high level of species connectivity. This
suggests that real ecosystems form one interconnected whole in which selection
leads to stronger interactions between the different types. Analogies with
niche and neutral theory are also considered.
