Before revision:  We discuss three ways diversity reservoirs are realised in practice : the microbial seed bank, climate refugia and lateral gene transfer and finally we simulate the effect of changing the reservoir size .
After revision:  We discuss three ways diversity reservoirs are realised in practice : the microbial seed bank, climate refugia and lateral gene transfer and conclude by discussing testable implications of an entropic hierarchy for the study of Earth history and the search for life in the universe .