Major temporal and spatial patterns of organic diversity on earth remain largely unexplained, although there is no lack of theories. Diversity theories suggest fundamental ecological and evolutionary principles which may apply to synthetic life. In general these theories relate to synthetic life in two ways: 1) They suggest factors which may be critical to the auto-catalytic increase of diversity and complexity in an evolving system. It may be necessary then to introduce these factors into an artificial system to generate increasing diversity and complexity. 2) Because it will be possible to manipulate the presence, absence, or state of these factors in an artificial system, the artificial system may provide an experimental framework for examining evolutionary and ecological processes that influence diversity.
The Gaussian principle of competitive exclusion states that no two species that occupy the same niche can coexist. The species which is the superior competitor will exclude the inferior competitor. The principle has been experimentally demonstrated in the laboratory, and is considered theoretically sound. However, natural communities widely flaunt the principle. In tropical rain forests several hundred species of trees coexist without any dominant species in the community. All species of trees must spread their leaves to collect light and their roots to absorb water and nutrients. Evidently there are not several hundred niches for trees in the same habitat. Somehow the principle of competitive exclusion is circumvented.
There are many theories on how competitive exclusion may be circumvented. One leading theory is that periodic disturbance at the proper level sets back the process of competitive exclusion, allowing more species to coexist [37,38,39]. There is substantial evidence that moderate levels of disturbance can increase diversity. In a digital community, disturbance might take the form of freeing blocks of memory that had been filled with digital organisms. It would be very easy to experiment with differing frequencies and patch sizes of disturbance.
One theory to explain the great increase in diversity and complexity in the Cambrian explosion [85] states that its evolution was driven by ecological interactions, and that it was originally sparked by the appearance of the first organisms that ate other organisms (heterotrophs). As long as all organisms were autotrophs (produce their own food, like plants), there was only room for a few species. In a community with only one trophic level, the most successful competitors would dominate. The process of competitive exclusion would keep diversity low.
However, when the first herbivore (organisms that eat autotrophs) appeared it would have been selected to prefer the most common species of algae, thereby preventing any species of algae from dominating. This opens the way for more species of algae to coexist. Once the ``heterotroph barrier'' had been crossed, it would be simple for carnivores to arise, imposing a similar diversifying effect on herbivores. With more species of algae, herbivores may begin to specialize on different species of algae, enhancing diversification in herbivores. The theory states that the process was auto-catalytic, and set off an explosion of diversity.
One of the most universal of ecological laws is the species area relationship
[52]. It has been demonstrated that in a wide variety of contexts,
the number of species occupying an ``area'' increases with the area.
The number of species increases in proportion to the area raised to a
power between 0.1 and 0.3. 
, where 0.1 < z < 0.3. The
effect is thought to result from the equilibrium species number being
determined by a balance between the arrival (by immigration or speciation)
and local extinction of species. The likelihood of extinction is greater
in small areas because they support smaller populations, for which a
fluctuation to a size of zero is more likely. If this effect holds
for digital organisms it suggests that larger amounts of memory will
generate greater diversity.