Drivers of β-diversity along latitudinal gradients revisited

Authors

  • Hong Qian,

    Corresponding author
    1. Research and Collections Center, Illinois State Museum, Springfield, IL, USA
    • Correspondence: Hong Qian, Research and Collections Center, Illinois State Museum, 1011 East Ash Street, Springfield, IL 62703, USA.

      E-mail: hqian@museum.state.il.us

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  • Shengbin Chen,

    1. Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection, Nanjing, China
    2. State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China
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  • Lingfeng Mao,

    1. State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
    2. Graduate School of Chinese Academy of Sciences, Beijing, China
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  • Zhiyun Ouyang

    1. State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China
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  • Editor: Andres Baselga

Abstract

Aim

Ecologists have generally agreed that β-diversity is driven at least in part by ecological processes and mechanisms of community assembly and is a key determinant of global patterns of species richness. This idea has been challenged by a recent study based on an individual-based null model approach, which aims to account for the species pool. The goal of the present study is twofold: (1) to analyse data sets from different parts of the world to determine whether there are significant latitude–β-diversity gradients after accounting for the species pool, and (2) to evaluate the validity of the null model.

Location

Global.

Methods

A total of 257 forest plots, each being 0.1 ha in size and having 10 0.01-ha subplots, were used. We conducted four sets of analyses. A modified version of Whittaker's β-diversity index was used to quantify β-diversity for each forest plot. A randomization procedure was used to determine expected β-diversity.

Results

The number of individuals per species, which characterizes species abundance distribution, alone explains 56.8–84.2% of the variation in observed β-diversity. Species pool (γ-diversity) explained only an additional 2.6–15.2% of the variation in observed β-diversity. Latitude explains 18.6% of the variation in raw β deviation in Gentry's global data set, and explains 11.0–11.6% of the variation in standardized β deviation in the global and three regional analyses. Latitude explains 33.2–46.2% of the variation in the number of individuals per species.

Main conclusions

Species abundance distribution, rather than species pool size, plays a key role in driving latitude–β-diversity gradients for β-diversity in local forest communities. The individual-based null model is not a valid null model for investigating β-diversity gradients driven by mechanisms of local community assembly because the null model incorporates species abundance distributions, which are driven by mechanisms of local community assembly and in turn generate β-diversity gradients.

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