We can now move on to consider the relationship between interspecific competition and ecological versatility, after a rather lengthy postponement stretching back to Chapter 4. Having established a modelling framework suitable for investigating exploitation competition in the previous chapter, I now wish to explore whether the existing ideas on the effects of different species on each other's resource use (i.e., interspecific competition) provide much in the way of general prediction. In particular, I ask: to what extent do the more complex models of exploitation strategies and tactics developed here, and the more meaningful representation of the variability in resource availability, affect the expectations developed by community theorists over the past three or four decades?

Competition between species has been regarded as a major if not the predominant factor in controlling the range and diversity of resources used by populations. Clearly, if interspecific competition were such a pervasive influence on resource use, then much of the observed variation in ecological versatility must arise from the impact of this process. That interspecific competition is expected to affect the breadth of resource use is reflected by some of the most emotive jargon of ecology, such as ‘competitive release’, ‘the compression hypothesis’, ‘resource partitioning [or segregation or differentiation]’, and ‘competitive exclusion’. The last term, competitive exclusion, seems to reflect an intuitive belief that species that are too similar to one another in ecological terms cannot coexist for long periods (Chesson 1991).