The second relaxation of the models in Chapter 4 is the consideration of spatial structure. Two major approaches are presented: patch-based models and grid-based models. Patch-based models are related to the metapopulation concept according to which a population consists of an ensemble of local populations each of which inhabits a habitat patch and interacts with other local populations through the dispersal of individuals. If a local population becomes extinct the empty habitat patch may be colonised by other local populations. In a grid-based model the model landscape consists of a grid of cells each of which may have particular properties, such as suitability for a particular species, and which may be occupied by one or more species or not. Grid-based models are generally more flexible than patch-based models. The dynamics of a grid-based model is demonstrated on the famous Game of Life which is further extended to demonstrate the importance of spatial structure.