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Midpoint attractors and species richness: Modelling the interaction between environmental drivers and geometric constraints
Author(s) -
Colwell Robert K.,
Gotelli Nicholas J.,
Ashton Louise A.,
Beck Jan,
Brehm Gunnar,
Fayle Tom M.,
Fiedler Konrad,
Forister Matthew L.,
Kessler Michael,
Kitching Roger L.,
Klimes Petr,
Kluge Jürgen,
Longino John T.,
Maunsell Sarah C.,
McCain Christy M.,
Moses Jimmy,
Noben Sarah,
Sam Katerina,
Sam Legi,
Shapiro Arthur M.,
Wang Xiangping,
Novotny Vojtech
Publication year - 2016
Publication title -
ecology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.852
H-Index - 265
eISSN - 1461-0248
pISSN - 1461-023X
DOI - 10.1111/ele.12640
Subject(s) - midpoint , species richness , ecology , range (aeronautics) , midpoint method , attractor , taxon , biology , geometry , mathematics , mathematical analysis , materials science , composite material
Abstract We introduce a novel framework for conceptualising, quantifying and unifying discordant patterns of species richness along geographical gradients. While not itself explicitly mechanistic, this approach offers a path towards understanding mechanisms. In this study, we focused on the diverse patterns of species richness on mountainsides. We conjectured that elevational range midpoints of species may be drawn towards a single midpoint attractor – a unimodal gradient of environmental favourability. The midpoint attractor interacts with geometric constraints imposed by sea level and the mountaintop to produce taxon‐specific patterns of species richness. We developed a Bayesian simulation model to estimate the location and strength of the midpoint attractor from species occurrence data sampled along mountainsides. We also constructed midpoint predictor models to test whether environmental variables could directly account for the observed patterns of species range midpoints. We challenged these models with 16 elevational data sets, comprising 4500 species of insects, vertebrates and plants. The midpoint predictor models generally failed to predict the pattern of species midpoints. In contrast, the midpoint attractor model closely reproduced empirical spatial patterns of species richness and range midpoints. Gradients of environmental favourability, subject to geometric constraints, may parsimoniously account for elevational and other patterns of species richness.