Overview

Understanding the cause of biodiversity gradients through time and in space are two first order questions of macroevolutionary theory. Both are potentially driven by a long-term interplay between biological systems (interactions between organisms, populations and species) and the physical environment (e.g. climate). One of the best ways to untangle the importance of these biotic and abiotic drivers of macroevolutionary patterns is using the fossil record of biomineralizing marine micro-organisms (Ezard et al., 2011).

This project aims to extend recent work on the macroevolution of the planktic foraminifera (Ezard et al., 2011), by applying similar methods to the best-sampled group of fossil marine phytoplankton, the coccolithophore algae. As the base of marine ecosystems, the phytoplankton are both closest to the fundamental climate-controlled physio-chemical environment of the oceans and are a potential driving force of evolution at higher trophic levels. Existing coccolithophore species diversity compilations show a clear decline in diversity from the early Eocene conditions of peak planetary warmth to a diversity minimum during the “one cold pole” climates of the Oligocene (Bown et al., 2004). Recent studies, however, have shown a substantial portion of missing coccolithophore diversity within this record, which is only present in locations with excellent calcareous microfossil preservation potential (Bown et al., 2008; Dunkley Jones et al., 2009).

This project will generate new species diversity and morphological disparity datasets from geographically dispersed, locations with excellent coccolith preservation. These data will be used to interrogate 1) the timing, nature and causes of global species diversity loss through the Eocene – Oligocene cooling; 2) the nature and temporal evolution of latitudinal diversity & disparity gradients and their relationship to the development of latitudinal temperature gradients through the Eocene and Oligocene.

Compilation of global coccolith diversity through time (Bown et al. 2004)

Methodology

The project will focus on detailed taxonomic and morphometric analyses of Eocene and Oligocene fossil coccoliths. This data will be the basis for determining species diversity and disparity metrics through space and time. Focusing on primary data collection, this will utilise sites across a range of latitudes that have good to excellent nannofossil preservation. This will overcome the potential for taphonomic loss that can reduce biodiversity in many deep-ocean locations. Together, these occurrence and morphometric data will be used to test the power of a range of explanatory variables for coccolithophore evolution, including first-order climate forcing, ocean stratification, atmospheric CO2 levels, species-diversity dependence and the diversity records of competing phytoplankton groups.

Training and Skills

CENTA students will attend 45 days training throughout their PhD including a 10-day placement. In the first year, students will be trained as a single cohort on environmental science, research methods and core skills. Throughout the PhD, training will progress from core skills sets to master classes specific to the student's projects and themes.

The student will receive detailed training in Cenozoic calcareous nannofossil taxonomy from Supervisors Dunkley Jones, Bown and CASE partner Gallagher. By the end of the PhD they will be expected to be an expert on the taxonomic diversity and temporal occurrence of Paleogene calcareous nannofossils, with immediate application to both research and industrial communities. Dr Butler will provide training in macroevolutionary data analysis, including the provision of appropriate detailed training in multi-variate statistical methods in R.

Timeline

Year 1: Training in Paleocene nannofossil taxonomy; data collection for key groups through the Paleocene.

Year 2: Training in Eocene nannofossil taxonomy; occurrence data collection for the Neogene.

Year 3: Compilation of occurrence data and derivation of most parsimonious phylogenies. Statistical modelling of new diversity records.

Partners and collaboration (including CASE)

CASE partners Network Stratigraphic Ltd, will provide both training in Paleogene calcareous nannofossil taxonomy and biostratigraphy, but more importantly, they will act as a “quality control” on the generated coccolith range data and proposed phylogenies. Using many years of industrial biostratigraphic experience, from sites across the globe, they will provide advice on potential missing or spurious occurrences.

In return, this project will provide a unique novel framework within which to frame current industrial biostratigraphic activities. Regular placements of the student with Network Stratigraphic will maximise this two-way knowledge transfer and provide the student with detailed training in industrial micropalaeontology.