Biodiversity

This page talks about experiments to achieved biodiversity in a computational ecology, a term used by Larry Yeager to describe Polyworld, and I guess this term would also apply to Evo(rand).

What is biodiversity? From Wikipedia: "it is a variation of life forms within a given ecosystem". If I can simplify, it would typically be measured by 2 parameters:

• the number of different species, such as species of plants, birds, etc., and
• diversity among those species, such as co-existence of plants, herbivores, carnivores, large and small, etc.

Another measure of bio-diversity is gene diversity in the ecosystem.

Now if we look at the phylogenetic tree of life that link all the life forms in the ecosystem back to from the origin of life, one would imagine that, in an ecosystem with biodiversity, the common ancestor to all life forms would be quite early back along that tree. Typically, the further back, the more gene diversity you have in your population. I'll put some picture to illustrate if I have time.

So what would be biodiversity in a computational ecology? Well, exactly the same thing: a simulated world where the common ancestor is an early creature in the life of the simulation. I have seen this when trying to achieve something else.

The objective I was pursuing is an ecology where plants, herbivores and carnivores co-exist for long periods of time, in a fairly stable ecosystem.

Evo(rand) is a simulator where the initial simulated creatures can potentially evolve to become a plant or a specialized herbivore or carnivore. I have had several attempts at achieving such stable ecosystem but repeatedly failed, even more than 10,000 simulated creatures.

Each time a small population started to eat plants, it would quickly get rid of all the plants, which is turn reduces the population of herbivores. In other words, the biodiversity remained very limited.

All along I was using a simulated world with a large sea and islands. But when I changed to a mountainous world with lakes, islands of evolution started to appear and there it was: a stable ecosystem with plants and herbivores co-existing.

In other worlds, a world of lakes created islands of evolution, which were sufficient to achieve biodiversity in an A-Life world.