Introduction

Diamond's assembly rule

The idea that there were rules to govern how communities might be assembled was first explored by Jared Diamond (1975) in his treatise on ‘assembly of species communities’. Although there were inklings of what was to come in earlier papers (Diamond 1973, 1974) the 1975 paper built on his mountain of observational data on the distribution of bird species on the many islands surrounding New Guinea to produce ‘incidence functions’. These incidence functions were then used to deduce or infer the ‘role’ or ‘strategy’ of that species, such as the supertramp strategy already described by Diamond (1974). Diamond's ideas were further developed (covering over 100 pages) culminating in his assembly rules predicting which species were able to coexist on islands in the New Guinea archipelago, in terms of allowed and forbidden combinations. An abbreviated version of his reasoning is shown in Fig. 1.1, which matches the resource utilization curves of four species of birds (dashed lines) to the availability of resources (resource production curves – solid lines) on islands with different levels of resources. By subtracting individual resource utilization curves from resource production curves, it is possible to obtain estimates of the distribution of the remaining resources allowing one to see which additional species could survive and which species requirements would exceed the resource levels available. In this way, Diamond was able to predict allowed and forbidden combinations of species.