1- IntroductionHow does an environment's topology affect the population dynamics of its inhabitants? Lack of attention to this simple, fundamental question has seriously hampered our theoretical understanding of population biology and epidemiology. For example, in this heyday of HIV, we are admonished daily by educators about the dangers of promiscuous activity; yet until recently [1] there were no quantitative theoretical studies of how the spread of a disease depends upon the detailed network of contacts between individuals. As critical as this oversight is for biology, it is even more so for artificial life. We can exert considerably more control over the design of digital organisms and their habitats than we can over that of natural or genetically-engineered biological organisms, and the range of topologies that we can imagine and experiment with is perhaps greater than what nature and culture have realized. If we are to understand and control the behavior of digital organisms, we absolutely must gain a clearer quantitative understanding of how topology influences population dynamics. First, I shall illustrate what I mean by topology by reflecting briefly on the variety of topologies that can be found in natural and artificial systems. Then, I shall select two simple ecological systems for quantitative study. In the first system, I study the dynamics of a single species; in the second, I study a particular brand of predator-prey interaction between two species. In both cases, I have been careful to scale the models in such a way that topological effects can be separated unequivocably from all other parameters and effects. I will conclude with a speculative generalization of my findings.
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