Ecological communities as complex systems
Jeff Nekola, Ph.D.
University of New Mexico
Wednesday, May 10, 2006
Pacific Forum – 3:00 p.m.
Patterns such as log-left-skewed Species Abundance Diagrams (SAD), power-law Species Area Relationships (SAR) and Species Time Relationships (STR), and nonlinear Distance-Decay of community similarity (DD) are being increasingly used by ecological theorists to try and decipher the mechanisms underlying community structure. However, the most profound outcome from these recent analyses has been largely ignored: predicted patterns from community models, no matter if based on neutrality or competition, provide largely identical results. The answer to this paradox is suggested when we observe similar patterns across a diverse group of phenomena, including gas thermodynamics, individual wealth, continental precipitation, distribution of mineral species, stock volumes, scientific citation frequencies, North American garden seed industry, global cuisines, word use frequencies, and Cowboy Junkies concert setlists. SAD, SAR, STR and DD thus appear to simply represent emergent statistical properties of complex systems. As such, they say more about the nature of ecological communities than the mechanisms which have created these patterns, and point to the limitations all ecologists must face when testing mechanistic hypotheses.