Small-scale spatial variability can affect community dynamics in many ecological and biological processes, such as predator-prey dynamics and immune responses. Spatial variability includes short-range neighbour-dependent interactions and small-scale spatial structure, such as clustering where individuals aggregate together, and segregation where individuals are spaced apart from one another. Yet, a large class of mathematical models aimed at representing these processes ignores these factors by making a classical mean-field approximation, where interactions between individuals are assumed to occur in proportion to their average density. Such mean-field approximations amount to ignoring spatial structure. In this work, we consider an individual-based model of a two-species community that is composed of consumers and resources. The model describes migration, predation, competition and dispersal of offspring, and explicitly gives rise to varying degrees of spatial structure. We compare simulation results from the individual-based model with the solution of a classical mean-field approximation, and this comparison provides insight into how spatial structure can drive the system away from mean-field dynamics. Our analysis reveals that mechanisms leading to intraspecific clustering and interspecific segregation, such as short-range predation and short-range dispersal, tend to increase the size of the resource species relative to the mean-field prediction. We show that under certain parameter regimes these mechanisms lead to the extinction of consumers whereas the classical mean-field model predicts the coexistence of both species.

小规模的空间变异会影响许多生态和生物过程中的群落动态，例如捕食者-猎物的动力学和免疫反应。空间变异性包括短距离邻居相关的相互作用和小规模的空间结构，例如个体聚集在一起的聚类和隔离个人彼此隔开的地方。但是，旨在代表这些过程的一大类数学模型通过进行经典的平均场近似来忽略了这些因素，其中假定了个体之间的交互作用与其平均密度成正比。这种平均场近似等于忽略了空间结构。在这项工作中，我们考虑了一个由消费者和资源组成的两物种社区的基于个体的模型。。该模型描述了后代的迁徙，捕食，竞争和扩散，并明确提出了不同程度的空间结构。我们将基于个人模型的仿真结果与经典平均场近似的解决方案进行比较，这种比较提供了关于空间结构如何驱动系统远离平均场动力学的见解。我们的分析表明，导致种内聚类和种间隔离的机制（例如短程捕食和短程分散）相对于平均场预测倾向于增加资源物种的规模。我们表明，在某些参数体制下，这些机制导致了消费者的灭绝，而经典的均值场模型预测了两种物种的共存。