PhD: Comparative palaeoecology of marine and terrestrial ecosystems

Large-scale patterns in the diversity of life on Earth are mostly described in terms of taxonomic diversity, typically the number of genera or families through time and space. These patterns include the long-term diversification history of life, mass extinctions, and the latitudinal diversity gradient. However, taxonomic diversity is just one of several dimensions of biodiversity. Recent work has shown that functional diversity—defined as the value and range of those species and organismal traits that influence ecosystem functioning (Edie et al. 2018)—provides vital complementary information on the origin and maintenance of biodiversity.

For example, analyses of plant life during mass extinctions have shown that while these intervals of time did not lead to catastrophic losses of higher taxa (such as families and orders), plant ecosystem structure was profoundly reorganised, and extinction risk at the species level was increased by functional traits such as complex reproductive biology and large leaf size (McElwain et al. 2007). Among animals, analyses of the functional diversity of marine organisms during the end-Permian mass extinction have shown that for benthic marine invertebrates, while the genus-level extinction rate was 62–74% all but one functional group persisted through the crisis (Foster and Twitchett 2014).

The overall goal of this PhD project is to gather new fossil data on the functional diversity of plants and benthic marine invertebrates through the Eocene and Oligocene Epochs (56–23 million years ago). This time interval represents an interval of long-term global cooling associated with the draw-down of atmospheric CO2, and encompasses the Eocene–Oligocene transition at 33–34 million years ago that saw ice growth, sea-level fall and accelerated extinction (Pearson et al. 2008).

This project will involve placing fossil plants and animals into frameworks of ecological function, and will provide data on the evolution of functional diversity over long-term macroevolutionary time-scales as well as geologically rapid time-scale associated with extinction. Such data is vital in order to understand how terrestrial and marine ecosystems respond in concert to climatic change, and is urgently needed as human activity places pressure on today's biota.

METHODOLOGY AND TRAINING
The data for this project will be gathered from specimens housed in the Natural History Museum, London, as well as other museums worldwide. Fossils from discrete time slices through the Eocene–Oligocene interval will be examined and scored for functional traits. For plants these groups will include reproductive and vegetative traits, for benthic marine invertebrates they will include traits related to feeding, motility and relationship to the substrate. Morphometric measurements will be taken in order to quantify the size and shape of fossil specimens.

This project will provide specific training in the practice of palaeoecology, systematic palaeontology and morphometrics. Depending on the skills and career goals of the successful applicant, training will also be provided in the use of large databases in macroevolutionary research, time series analysis, and the algorithmic quantification of morphology from discrete characters. These skills are particularly relevant to a career in science, either in a traditional research setting in a university, or in a curatorial setting in a museum or botanical garden.

REFERENCES
Edie, S. M., Jablonski, D., and Valentine, J. W. (2018) 'Contrasting responses of functional diversity to major losses in taxonomic diversity', PNAS, 115, pp. 732-737.
Foster, W. J. and Twitchett, R. J. (2014) 'Functional diversity of marine ecosystems after the Late Permian mass extinction event', Nature Geoscience, 7, 233-238.
McElwain, J. C., Popa, M. E., Hesselbo, S. P., Haworth, M. and Surlyk, F. (2007) 'Macroecological responses of terrestrial vegetation to climatic and atmospheric change across the Triassic/Jurassic boundary in East Greenland', Paleobiology, 33, 547-573.
Pearson, P. N. et al. (2008) 'Extinction and environmental change across the Eocene-Oligocene boundary in Tanzania' , Geology, 36, 179-182.