一个三物种生态系统模型

本文利用属性集合来定义物种，对于同一物种中的不同个体，各种属性所表现出的强度不同，导致了个体之间的差异性．对一个物种而言，它具有的某方面功能是由物种的不同属性体现于这方面的能力所共同决定的．本文对具有环状捕食结构的三物种构成的生态系统，以各物种的每个属性对和捕食逃逸能力的贡献方式为基础，将属性分为四类．讨论了四类属性随时间的演化规律．从所得的结果发现，随着时间的延伸，三物种可以稳定的共存；另外，对物种捕食和逃逸有利的属性在平均意义下是进化的，而对捕食和逃逸无作用的属性却无法被淘汰．

An Ecosystem Model with Three Species

A species can be defined by the aggregate of attributions in this paper. The difference of the same species＇ individuals is embodied by different intensity shown from corresponding attributions. Each attribution may take different effects on some abilities of a species. Thus, a kind of abilities for a certain species lies on all the attributions which relate to this ability. We discuss an ecosystem constituted of three species with circular preying relation with different reproduction modes. The attributions are sorted based on whether it takes effects on preying and escaping or not. We discuss the evolution of the four kinds of attributions as the function of time steps. The results show that three species will coexist. Furthermore, the attributions which are beneficial to preying and escaping will increase fast. But the attributions with no contribution to preying and escaping will not be extinction.