Human ecology

Abstract model of nutrient cycling in an ecosystem

A model I created in Winter '94-'95 while re-taking the final year of my B.Sc. Astrophysics.
This discrete model was originally designed to investigate speciation in asexual organisms. The assumption was that metabolism requires organisms to change their chemical environment from one that contains nutrients to one the contains waste products. The interactions of different organisms, with different nutrient requirements, set up nutrient cycles. These cycles produce temporal concentrations of nutrients that affect the fitness of the organisms at each particular time. Surviving organisms produce offspring that may have mutations in their nutrient requirements.

I hoped that this model would show speciation events. Although these occur, the practical limitations of the model may not allow these events to be given much significance: they may just be artifacts of the model. However, the model does exhibit some interesting effects.


Details of the model
This version of the model considers interactions between eight abstract "nutrients". There is a finite amount of nutrients but any nutrient can be converted into any other nutrient by the action of an "organism". The size of the nutrient space is specified by the user as "Space"

Organisms have four parameters:

typical output screen

The first eight columns on the left represent the numbers of nutrient in each state. The second eight columns represent the numbers of organisms per input nutrient type. The next column represents the total number of organisms at that time. (In all these column the numbers are represented in base-16, this reduces the amount of horizontal space required to display the data). The last two columns give the time and the average mutation rate.

This model was inspired by reading:


Programs... (Virus free by Norton Antivirus 5.0 - although I haven't updated this virus library recently)

Links at other sites...
Created 7/7/99
Modified 6/10/99