  In past work, we developed a computational model of the evolution of
symbiotic entities (Model-S), based on Conway's Game of Life. In this article,
we examine three trends that biologists have observed in the evolution of
symbiotes. (1) Management: If one partner is able to control the symbiotic
relation, this control can reduce conflict; thus, evolutionary selection
favours symbiotes that have a manager. (2) Mutualism: Although partners in a
symbiote often have conflicting needs, evolutionary selection favours symbiotes
in which partners are better off together inside the symbiote than they would
be as individuals outside of the symbiote. (3) Interaction: Repeated
interaction among partners in symbiosis tends to promote increasing fitness due
to evolutionary selection. We have added new components to Model-S that allow
us to observe these three trends in runs of Model-S. The new components are
analogous to the practice of staining cells in biology research, to reveal
patterns that are not usually visible. When we measure the fitness of a
symbiote by making it compete with other symbiotes, we find that fitter
symbiotes have significantly more management, mutualism, and interaction than
less fit symbiotes. These results confirm the trends observed in nature by
biologists. Model-S allows biologists to study these evolutionary trends and
other characteristics of symbiosis in ways that are not tractable with living
organisms.
