The ecological versatility (and ubiquity) of organisms clearly varies greatly both in terms of the overall magnitude of the differences between organisms (e.g., versatility of species A > versatility of species B), but also secularly (e.g., versatility of species Asummer > versatility of species Awinter) and spatially (e.g., versatility of population Aheath > versatility of species Awoodland). Although some organisms display rather consistently limited exploitation of resources even in the face of the availability of a wide assortment of alternatives, it seems that the overwhelming majority of organisms either alter their resource use dynamically or are opportunistic to some extent. By analysing ecological versatility in a general way as I have done in this book, it seems that the claims of widespread, extreme specificity characterizing some sorts of organisms and interactions probably have been overstated. For example, as we have seen, many parasites exhibit strikingly different morphologies when they infect alternative hosts and, in the absence of independent genetic information, this phenomenon can misleadingly increase the perceived degree of host specificity (Downes 1990). Thus, the range and dynamism of ecological versatility have struck me most during the preparation of this volume.

Of course, these comments are just a crude summary of the patterns of versatility evident in natural communities – they do not refer to the processes leading to the patterns. Many of the propositions for explaining the variation in versatility and ubiquity have formed the subject matter of the preceding five chapters.