This book up to here has largely been a commentary on the specific, that is, on the variety and complexity of patterns of ecological versatility evident in nature. It is desirable to pass on from this particularity to produce or look for a more general picture of the reasons for, and consequences of, different patterns of versatility in natural populations. How might this be accomplished? The usual approach has been to develop models that link patterns of resource use with population dynamics in either a contemporary or evolutionary context (e.g., Roughgarden 1972, Eldredge 1989, Ebenman 1992, Holt and Gaines 1992). It is worth emphasizing that population dynamics have been intimately connected with the breadth of resource use in the development of ecological theory, as we have seen previously with the models of Glasser. That there should be a connexion between densities and versatility is a much older idea than this and was formally developed by Svärdson (1949) and others many years ago. Thus, I believe that the modelling of the relationship between versatility and population dynamics is a necessary component of a monograph devoted to the topic of ecological versatility.

An avenue to modelling that seems to have been the first (or perhaps preferred) mode of attack has been to use mathematical models (e.g., Roughgarden 1979, Mueller and Ayala 1981, Nisbet and Gurney 1982, Ginzburg 1986, Hofbauer and Sigmund 1988). Population dynamics in these models often are represented in a ‘phenomenological’ way, which simply means that the equations describe the numerical dynamics of populations without necessarily enunciating the mechanisms underlying those dynamics (Leon and Tumpson 1975).