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Arthropod community structure along a latitudinal gradient: Implications for future impacts of climate change

Authors

  • NIGEL R. ANDREW,

    Corresponding author
    1. Key Centre for Biodiversity and Bioresources, Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
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  • LESLEY HUGHES

    1. Key Centre for Biodiversity and Bioresources, Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
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*Present address: Zoology, Centre for Ecology, Evolution and Systematics, University of New England, Armidale, New South Wales 2351, Australia.
Email: nigel.Andrew@une.edu.au

Abstract

Abstract  The structure of free-living arthropod communities on the foliage of Acacia falcata was assessed along an extensive latitudinal gradient in eastern Australia. We hypothesized that abundance and biomass of arthropods within feeding groups would increase from temperate latitudes towards the tropics. We also hypothesized that the ratio of carnivores to herbivores would be consistent along the latitudinal gradient. Three sites at each of four latitudes, spanning 9° and 1150 km (Batemans Bay, Sydney, Grafton, Gympie in Australia), were sampled every season for 2 years, using pyrethrum knockdown. Abundance and biomass (based on dry weight) of arthropods within eight feeding groups were measured. The relative size of the feeding groups, and the ratio of carnivores to herbivores were then compared among latitudes and seasons. We found no consistent north to south (tropical to temperate) change in feeding group structure in terms of abundance. A weak latitudinal trend was evident for predator biomass, consisting of a reduction from north to south, but no significant trends in biomass for other feeding groups were found. Relative abundance and relative biomass of both carnivores and herbivores, as well as the ratio of carnivores to herbivores were consistent among latitudes. Finally, we compared a subset of these data to arthropod communities found on congeneric host species at individual sites along the latitudinal gradient. Overall, 68% of comparisons showed no significant differences in abundance or biomass within different feeding groups between host plants and among latitudes. We conclude that arthropod communities show consistencies among latitudes and between congeneric host species, in terms of feeding group and trophic structure. These results have implications for predicting the impacts of future climate change on arthropod communities.

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