PARENT SESSION
Oral Session #15: Ecosystem Ecology. Presiding: J. Jenkins.
Monday, August 6, 2001. 1:00 PM to 4:45 PM. Hall of Ideas F.
Are animal body mass patterns from structurally similar ecosystems similar?
Allen, Craig1, Holling, C2, 1 2
ABSTRACT- The Textural-Discontinuity Hypothesis proposes that discontinuous animal body mass distributions reflect discontinuous landscape structures available for animals at different scales. If body mass patterns reflect the cross-scale organization of ecosystems, then ecosystems that are structured by similar processes are predicted to contain animal communities that have similar body mass patterns. Mediterranean climate ecosystems are similar structurally, but contain animal communities with evolutionary distinct origins. There are more Mediterranean climate ecosystems than there are of other types of terrestrial ecosystem, and they therefore present the strongest test of the Textural-Discontinuity Hypothesis. We used the body mass distributions of the mammals of 5 Mediterranean-climate ecosystems and determined if the distributions were discontinuous, and if so we then compared body mass patterns among the systems. Discontinuities were determined with computer simulations with a null model, cluster analysis and CART analysis. Patterns were compared with pairwise Phi correlations and by adding the binary vectors representing the body mass patterns of each system. All data sets were discontinuous as determined by all 3 methods. State agreement among all comparisons ranged from 50 - 80%, and Phi correlations among sites ranged from 0 - 0.45. Adding the vectors representing the body mass patterns of the systems conserved, rather than obscured, the patterns. We conclude that the body mass patterns of Mediterranean-climate ecosystems are similar despite phylogenetic dissimilarity, and that these findings support the Textural-Discontinuity Hypothesis.
KEY WORDS: textural-discontinuity hypothesis, cross-scale ecology, ecological structure, body mass pattern