Measure representation of evolving genealogies.

We study evolving genealogies, i.e. processes that take values in the space of (marked) ultra-metric measure spaces and satisfy some sort of "consistency" condition. This condition is based on the observation that the genealogical distance of two individuals who do not have common ancestors up to a time $h$ in the past is completely determined by the genealogical distance of the respective ancestors at that time $h$ in the past. Now the idea is to color all possible ancestors at time $h$ in the past and measure the relative number of their descendants. The resulting collection of measure-valued processes (the construction is possible for all $h$) is called a measure representation. As a main result we give a tightness criterion of evolving genealogies in terms of their measure representation. We then apply our theory to study a finite system scheme for tree-valued interacting Fleming-Viot processes.