  Cell reproduction involves replication of diverse molecule species, in
contrast to simple replication system with fewer components. Here, we address
why such diversity is sustained despite the efficiency of simple replication
systems, using a cell model with catalytic reaction dynamics that grew by
uptake of environmental resources. Limited resources led to increased diversity
of components within the system, and the number of coexisting species increased
with a negative power of the resource abundances. The diversity was explained
from the optimum growth speed of the cell, determined by a tradeoff between the
utility of diverse resources and the concentration onto fewer components to
increase the reaction rate.
