GSA Annual Meeting in Denver, Colorado, USA - 2016

Paper No. 104-7
Presentation Time: 9:45 AM


FENTON, Isabel S.1, PEARSON, Paul N.2, DUNKLEY JONES, Tom3, FARNSWORTH, Alex4, LUNT, Dan J.4, MARKWICK, Paul J.5 and PURVIS, Andy6, (1)Department of Life Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, United Kingdom, (2)School of Earth and Ocean Sciences, Cardiff University, Park Place, Cardiff, CF10 3AT, United Kingdom, (3)School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom, (4)School of Geographical Sciences and Cabot Institute, University of Bristol, Bristol, BS8 1SS, United Kingdom, (5)Getech, Elmete Hall, Elmete Lane, Leeds, LS8 2LJ, (6)Department of Life Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, United Kingdom; Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, SL5 7PY, United Kingdom,

Planktonic foraminifera are calcareous zooplankton found throughout the world’s oceans. They have arguably the most detailed fossil record of any group, making them ideal for studying macroecology through deep time. Using global Recent (coretop) assemblage data, we first modelled how environmental variables shape macroperforate planktonic foraminiferal communities today. Temperature and salinity emerge as the most significant variables for predicting diversity, although productivity and seasonality are also important; the relative importance of these variables differs between ocean basins. We then tested the temporal transferability of the present-day models by comparing the diversity predicted for Eocene conditions with data collated from offshore and onshore sites worldwide throughout the Eocene. The results indicate the modern latitudinal diversity gradient – lower richness towards the poles – developed through the Eocene. By the Late Eocene, environment-diversity relationships were similar to those found today, but the match between statistical model predictions and data are less good in the early Eocene. Three possible causes for this mismatch are considered: the environmental estimates are inaccurate, the statistical model misses relevant variables, or the intercorrelations among facets of diversity – e.g. richness, evenness, functional diversity – have changed over geological time. These analyses shed light on the role of the Eocene global cooling in establishing today's latitudinal diversity gradient – one of the most powerful general rules in biogeography and macroecology.
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