Local and regional ecological morphology of dung beetle assemblages across four biogeographic regions

Authors

  • Daegan J. G. Inward,

    Corresponding author
    1. Department of Entomology, Natural History Museum, Cromwell Road, London SW7 5BD, UK
    2. Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot SL5 7PY, UK
    3. Forest Research, Alice Holt Lodge, Farnham, Surrey GU10 4LH, UK
      Daegan Inward, Forest Research, Alice Holt Lodge, Farnham, Surrey GU10 4LH, UK.
      E-mail: daegan.inward@forestry.gsi.gov.uk
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  • Richard G. Davies,

    1. Department of Entomology, Natural History Museum, Cromwell Road, London SW7 5BD, UK
    2. Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot SL5 7PY, UK
    3. Centre for Ecology, Evolution and Conservation, School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK
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  • Claire Pergande,

    1. Department of Entomology, Natural History Museum, Cromwell Road, London SW7 5BD, UK
    2. Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot SL5 7PY, UK
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  • Andrew J. Denham,

    1. Department of Entomology, Natural History Museum, Cromwell Road, London SW7 5BD, UK
    2. Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot SL5 7PY, UK
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  • Alfried P. Vogler

    1. Department of Entomology, Natural History Museum, Cromwell Road, London SW7 5BD, UK
    2. Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot SL5 7PY, UK
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Daegan Inward, Forest Research, Alice Holt Lodge, Farnham, Surrey GU10 4LH, UK.
E-mail: daegan.inward@forestry.gsi.gov.uk

Abstract

Aim  Niche partitioning within species assemblages is thought to influence species packing and/or total niche space occupied. The evolution of dung beetles (Scarabaeinae) is likely to have been strongly influenced by inter-specific competition, leading to niche partitioning. We consider whether local-scale processes leave a signature in regional patterns of functional diversity in dung beetle assemblages, and investigate the correlation between total exploited ecomorphological space and density of species packing with increased species richness. We test whether ecomorphological space occupied by local assemblages reflects that of their regional species pool, and the extent to which ecomorphological space is convergent or divergent within functional groups across regional pools.

Location  Neotropics, Africa, Australia and Madagascar.

Methods  Dung beetle assemblages were collected in a standardized manner from four biogeographic regions. Ecomorphological similarity among the assemblages was assessed by multivariate analysis of 19 linear measurements for 300 species and three functional nesting types (roller, tunneller or dweller), firstly on a local level within the Neotropics and Afrotropics, and then between the regional species pools.

Results  Key body measurements, in particular the hind tibia, separated rollers and tunnellers into largely non-overlapping entities along the first three axes of the shape analysis. Three Neotropical assemblages, which vary widely in species numbers, each harboured a similar amount of morphometric variation, resulting in increasingly dense species packing with greater species richness. Similar findings were obtained in two South African assemblages. Assemblages in the four biogeographic regions showed largely similar distributions of ecomorphological variation, including the separation of rollers and tunnellers, despite their distant phylogenetic relationships. Ecomorphological similarity among regions was particularly high in tunnellers, whilst the rollers exhibited greater regional differentiation.

Main conclusions  Local assemblages evidently represent the full diversity of functional groups available in the regional pool, even in species-poor assemblages. There is a strong trend towards convergence in morphology separating tunnellers and rollers in phylogenetically independent lineages. The ecomorphological similarity of regional assemblages suggests that morphological convergence is the result of common selective forces active within the assemblages themselves. This lends support to the widely hypothesized effect of inter-specific interactions and niche partitioning in determining assemblage composition and lineage evolution in the Scarabaeinae.

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