  We consider the inclusion process on the complete graph with vanishing
diffusivity, which leads to condensation of particles in the thermodynamic
limit. Describing particle configurations in terms of size-biased and
appropriately scaled empirical measures of mass distribution, we establish
convergence in law of the inclusion process to a measure-valued Markov process
on the space of probability measures. In the case where the diffusivity
vanishes like the inverse of the system size, the derived scaling limit is
equivalent to the well known Poisson-Dirichlet diffusion, offering an
alternative viewpoint on these well-established dynamics. Moreover, our
approach covers all scaling regimes of the system parameters and yields a
natural extension of the Poisson-Dirichlet diffusion to infinite mutation rate.
We also discuss in detail connections to known results on related Fleming-Viot
processes.
