Research Article

The geography of biodiversity change in marine and terrestrial assemblages

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Science  18 Oct 2019:
Vol. 366, Issue 6463, pp. 339-345
DOI: 10.1126/science.aaw1620

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  • Changing biodiversity in terrestrial assemblages without insects: a comment on Blowes et al “The geography of biodiversity change in marine and terrestrial assemblages”
    • M. Alex Smith, Associate Professor, Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada

    Blowes et al (1) recently reported a global and rapid re-organisation of biological diversity and abundance. Their conclusions were reached using a collection of long-term monitoring studies (BioTIME - 2). However, the BioTIME dataset is fundamentally influenced (as is much of ecology) by a sampling bias towards plants and vertebrates (two taxa comprising more than 70% of BioTIME), while the terrestrial world’s most diverse group – the insects (3) –represent only 5% of the data. Moreover, BioTIME studies tend to occur in northern-hemisphere temperate systems (only ~16% are tropical). These qualities are more than nuances – they fundamentally change what conclusions can be derived from the dataset and furthermore these characteristics could be used to call attention to those missing taxa and regions. This is not to criticise BioTIME itself because there is currently no better resource. Yet we must use extreme caution when we extrapolate trends derived from a dataset containing such biased characteristics. Blowes et al found that, on average, assemblage richness is not changing, but the dataset from which they derived this conclusion is not richly filled in the terrestrial environment as long-term datasets involving insects (and in particular from the tropics) remain underrepresented. The use of datasets such as BioTIME ought to be accompanied by a call to better understand where fundamental gaps exist. Such absences are a glaring concern and ought to be of growing impor...

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    Competing Interests: None declared.

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