  Neutral models aspire to explain biodiversity patterns in ecosystems where
species difference can be neglected, as it might occur at a specific trophic
level, and perfect symmetry is assumed between species. Voter-like models
capture the essential ingredients of the neutral hypothesis and represent a
paradigm for other disciplines like social studies and chemical reactions. In a
system where each individual can interact with all the other members of the
community, the typical time to reach an absorbing state with a single species
scales linearly with the community size. Here we show, by using a rigorous
approach within a large deviation principle and confirming previous approximate
and numerical results, that in a heterogeneous voter model the typical time to
reach an absorbing state scales exponentially with the system size, suggestive
of an asymptotic active phase.
