caa a22 4500 469097655 CHVBK 20180323133035.0 cr unu---uuuuu 170328e19920901xx s 000 0 eng 10.1007/BF00317632 doi (NATIONALLICENCE)springer-10.1007/BF00317632 Competitive exclusion, or species aggregation? [Elektronische Daten] An aid in deciding [Lewi Stone, Alan Roberts] Summary: There is a long-standing dispute over whether the analysis of species co-occurrence data, typically on islands in an archipelago, can disclose the forces at work in structuring a community. Here we present and utilise three "scores” S, C and T. S gives the mean number of islands shared by a species pair in the presence/absence data under study. The scores C and T are based on the way that a pair of species occurs on a pair of islands. When each species occurs on a different island, this adds to the "checkerboard score” C; if they occupy the same island, this increases the "togetherness score” T. In judging whether observed values of S, C and T are compatible with a null hypothesis assuming no species interaction, we follow Connor and Simberloff (1979) in generating a "control group” of (constrained) simulated incidence patterns. Presence/absence matrices can have paradoxical features, in combining a high mutual exclusion by species (checkerboardedness) with a degree of species aggregation that is also high. We show that this is in fact inevitable — that, given the usual contraints, C and T can differ only by a constant. This means that extreme checkerboardedness can be produced by forces making for species aggregation, just as well as by those making for avoidance. If we restrict our attention to a subset of species, the constraints are less rigid and the S, C and T scores are somewhat freer to vary. We consider the confamilial subsets in the Vanuatu archipelago as likely candidates for revealing any competition forces at work. Calculating the actual S, C and T scores for these subsets, we compare them with the corresponding scores in a sample of simulated colonization patterns. The actual species-distributions differ significantly from what we would expect if the colonization choices of different species were uncorrelated (save for some biological constraints). The confamilial species of the real world share more islands, and occur in a pattern less checkerboarded, and more aggregated, than their simulation counterparts. This suggests that competition pressures, if they exist, are overcome by countervailing factors. The method used is applicable in other ways, and to a wider class of problems, in analysing the forces behind community structure. Springer-Verlag, 1992 Species co-occurrence nationallicence Bird distributions nationallicence Community structure nationallicence Coexistence principle nationallicence Stone Lewi Australian Environmental Studies, Griffith University, 4111, Nathan, Queensland, Australia aut Roberts Alan Graduate School of Environmental Science, Monash University, 3168, Clayton, VI, Australia aut Oecologia Springer-Verlag 91/3(1992-09-01), 419-424 0029-8549 91:3<419 1992 91 442 https://doi.org/10.1007/BF00317632 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00317632 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Stone Lewi Australian Environmental Studies, Griffith University, 4111, Nathan, Queensland, Australia aut NATIONALLICENCE 700 1- Roberts Alan Graduate School of Environmental Science, Monash University, 3168, Clayton, VI, Australia aut NATIONALLICENCE 773 0- Oecologia Springer-Verlag 91/3(1992-09-01), 419-424 0029-8549 91:3<419 1992 91 442 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer