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The mid‐domain effect cannot explain the diversity gradient of Nearctic birds
Author(s) -
Hawkins Bradford A.,
DinizFilho José Alexandre Felizola
Publication year - 2002
Publication title -
global ecology and biogeography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.164
H-Index - 152
eISSN - 1466-8238
pISSN - 1466-822X
DOI - 10.1046/j.1466-822x.2002.00299.x
Subject(s) - nearctic ecozone , diversity (politics) , ecology , domain (mathematical analysis) , bounded function , space (punctuation) , null model , point (geometry) , statistical physics , econometrics , mathematics , biology , computer science , geometry , physics , mathematical analysis , sociology , taxonomy (biology) , anthropology , operating system
A recent explanation for diversity gradients proposes a ‘null model’ based on how species ranges are constrained by the geometry of bounded domains. We conduct a test of this hypothesis by comparing patterns predicted by two two‐dimensional geometric models against observed diversity patterns for terrestrially feeding Nearctic birds. Consistent with previous tests in two‐dimensional space, we find empirical support for the hypothesis to be very weak. We also point out a fundamental conceptual flaw in the hypothesis with respect to the key assumption that ranges can exist independently of the environment in which they are embedded that undermines its theoretical basis as well. We conclude that the mid‐domain effect has little empirical support and no theoretical support for its existence, and recommend that it be eliminated as a potential explanation for diversity gradients.