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Indiscriminate data aggregation in ecological meta-analysis underestimates impacts of invasive species

Nature Ecology & Evolution volume 4, pages 312–314 (2020)Cite this article

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Matters Arising to this article was published on 17 February 2020

The Original Article was published on 08 April 2019

arising from A. Anton et al. Nature Ecology & Evolution https://doi.org/10.1038/s41559-019-0851-0 (2019)

One of the main objectives of ecological meta-analysis is to aggregate and average effect sizes (Hedges’ g in ref. 1) across different case studies in search of generality2,3. However, identifying the optimal aggregation level is complicated; averaging effect sizes across increasingly detailed data aggregations reduces replication levels, test power and scientific generality, and eventually reverts the analysis back to idiosyncratic case studies. By contrast, coarse and indiscriminate data aggregations can cancel out opposing effect sizes and may underestimate impacts and fail to identify the underpinning processes. I exemplify below how indiscriminate data aggregation in ref. 1 could affect conclusions about invasion impacts. Specifically, I illustrate how the reported small effect sizes arose, in part, because data were aggregated across invader characteristics and ecological responses (Fig. 1a), across community responses where the invader’s own data were either included or excluded (Fig. 1b) and across different types of uninvaded control (Fig. 1c).

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Fig. 1: Illustration of how the impacts of invasion change depending on data aggregation of invader characteristics and native responses, different analytical approaches and different controls.

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  1. Centre for Integrative Ecology and Marine Ecology Research Group, School of Biological Sciences, University of Canterbury, Christchurch, New Zealand

    Mads Solgaard Thomsen

  2. UWA Oceans Institute and School of Plant Biology, University of Western Australia, Crawley, Western Australia, Australia

    Mads Solgaard Thomsen

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Correspondence to Mads Solgaard Thomsen.

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Solgaard Thomsen, M. Indiscriminate data aggregation in ecological meta-analysis underestimates impacts of invasive species. Nat Ecol Evol 4, 312–314 (2020). https://doi.org/10.1038/s41559-020-1117-6

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