Patterns of rain forest plant endemism in subtropical Australia relate to stable mesic refugia and species dispersal limitations

Authors

  • Lui C. Weber,

    Corresponding author
    1. School of Biological Sciences, The University of Queensland, St Lucia, QLD, Australia
    • Correspondence: Lui C. Weber, School of Biological Sciences, The University of Queensland, St Lucia, QLD 4072, Australia.

      E-mail: lui.weber@uqconnect.edu.au

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  • Jeremy VanDerWal,

    1. Centre for Tropical Biodiversity and Climate Change, School of Marine and Tropical Biology, James Cook University of North Queensland, Townsville, QLD, Australia
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  • Susanne Schmidt,

    1. School of Agriculture and Food Sciences, The University of Queensland, St. Lucia, QLD, Australia
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  • William J. F. McDonald,

    1. Queensland Herbarium, Queensland Government Department of Environment and Resource Management, Brisbane Botanic Gardens – Mt Coot-tha, Toowong, QLD, Australia
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  • Luke P. Shoo

    1. School of Biological Sciences, The University of Queensland, St Lucia, QLD, Australia
    2. Centre for Tropical Biodiversity and Climate Change, School of Marine and Tropical Biology, James Cook University of North Queensland, Townsville, QLD, Australia
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Abstract

Aim

Our aims were to identify centres of endemism and to infer whether these areas have functioned as refugia for subtropical rain forest plants through historical climate fluctuations.

Location

Subtropical eastern Australia (23–33° S; 145–155° E).

Methods

We collated 25,000 records of 179 endemic rain forest plants to identify geographical areas with unusually high concentrations of endemic taxa and range-restricted endemics. We then tested whether centres of endemism coincide with other features indicating refugia, including habitat stability over 120,000 years, and we related dispersal patterns to past habitat stability using seed weight as a surrogate for dispersal ability of endemic plant taxa.

Results

We identified five main centres of endemism. Historical stability and other processes affecting diversity, including current rainfall, rain forest area, and topographic complexity, explained 58% of variation in plant-weighted endemism. Taxa with poor dispersal ability were concentrated in the areas that were most stable historically.

Main conclusions

Several lines of evidence suggest that centres of endemism have functioned as important refugia for subtropical rain forest taxa through historical climate fluctuations. The highest concentrations of range-restricted endemic species occur in locations that are predicted to have maintained stable rain forest habitat over at least the past 120,000 years. This association was independent from other factors that were expected to promote diversity (i.e. rain forest area and current environmental suitability). These locations have disproportionately high concentrations of species with poor dispersal ability (large-seeded species).

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