The goal of the experiments described in this paper is to exercise the power of Gecko's geometric-energetic approach. The elements of biological realism and abstraction are described for the individual-based components of an ecosystem. Resultant population-level qualitative behaviors are explored.
The individual-based components of Gecko include gross primary
production, over a constrained space, and several basic species types.
Organisms are abstracted as spheres on
the resource-producing plane. They have behaviors to acquire food,
assimilate food at realistic efficiencies, and pay metabolic taxes at
allometrically specified rates (
).
Creatures interact locally, with their
neighborhoods circumscribed by their radii, determined in turn
by their size---the biomass they have amassed. Thus in addition to having
position in two dimensions, Gecko creatures have the spatiotemporal
property of extent, with ramifications
in both opportunities and liabilities. Infant size,
reproductive size, and starvation size, are equivalent
to biomass thresholds for each species. Reproduction is asexual and
independent of any clock. The clock used in this paper
ticks monotonous days of no greater cycle.
Several natural qualitative ecosystem level behaviors fall out naturally from this spatial-energetic model. The system in three trophic levels demonstrates the qualitative trophic cascade expected in such a scenario. In a stable system, the proportions of energy stored in each trophic level compare surprisingly well with the proportions in natural trophic pyramids. Multiple-sized producers coexist easily. This easy coexistence follows for any sessile close-packed organisms competing for an area-based food supply. This is true of some animals, such as barnacles, and not true of some plants, such as phytoplankton. Non-specialized mobile consumers, on the other hand, are not found to coexist with the behaviors supplied to date.
It is hoped that Gecko's performance in the experiments introduced here, recommends its use for more challenging questions in the area of ecosystem dynamics. Research in this area has commenced [16].