Dr Maria Dornelas kicks off the first seminar of Hilary Term

This week’s seminar was from Dr Maria Dornelas, who presented her research on patterns of biodiversity change over time in the Anthropocene, using the bioTIME database. This database collates studies from across the globe that have recorded biodiversity levels over time, and contains >12.6 million records. In the face of high-profile research suggesting an unprecedented human driven impact on the world’s ecosystems1–4, Dr Dornelas’ somewhat controversial work suggests that at the local level there is on average no biodiversity change over time5. However, at this local scale they find a change in community composition, which could have implications for ecosystem function.

Maria was stimulated to study trends in biodiversity over time by her observation of significant losses of coral species at one of her field sites in response to cyclone and bleaching events. This prompted her to ask, is this the case everywhere? Although her results suggest that average trends in biodiversity change are neutral, this integrates studies from across the world: some showing increasing and others decreasing biodiversity trends over time. Maria acknowledged that the bioTIME database contains some spatial gaps, and there is interesting work suggesting that the database may underrepresent areas of the globe that are particularly threatened by human actions and hotspots of biodiversity6, which potentially invalidates the trends found.

It was great to have such a topical talk in the Department, which has stimulated a lot of interesting discussions. It is important to ask the question, are these results truly representative of global patterns of biodiversity change in the Anthropocene? And what could the implication of these results be on future conservation priorities? It will be interesting to see how these conclusions change as the bioTIME database increases in size and draws in more studies from underrepresented geographical locations.

  1. Barnosky, A. D. et al. Has the Earth’s sixth mass extinction already arrived? Nature 471, 51–57 (2011).
  2. Lister, B. C. & Garcia, A. Climate-driven declines in arthropod abundance restructure a rainforest food web. Proc. Natl. Acad. Sci. 115, (2018).
  3. Hallmann, C. A. et al. More than 75 percent decline over 27 years in total flying insect biomass in protected areas. PLoS One 12, e0185809 (2017).
  4. Newbold, T. et al. Global effects of land use on local terrestrial biodiversity. Nature 520, 45–+ (2015).
  5. Dornelas, M. et al. Assemblage Time Series Reveal Biodiversity Change but Not Systematic Loss. Science (80-. ). 344, 296–299 (2014).
  6. Gonzalez, A. et al. Estimating local biodiversity change: a critique of papers claiming no net loss of local diversity. Ecology 97, 1949–1960 (2016).


Emily Warner is a DPhil Candidate in the Department through the NERC Doctoral Training Partnership in Environmental Research. She can be found on @EmilyWarner28.

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