PhD: Out of Africa: Animals, traits, and oxygen in the Ediacaran Nama Group, Namibia

Background:
The Ediacaran-Cambrian Radiation, starting ca. 570 Ma, marks the appearance of abundant and diverse animals (metazoans), including the rise of bilaterians, in the fossil record. Many groups, lifestyles and ecologies appeared, and this was accompanied by extremely high rates of extinction and turnover. This interval is also marked by low levels of oxygen in shallow marine seas, but this was punctuated by intervals of higher oxygen pulses, which show a close relationship to the sea-level and the carbon cycle, as evidenced by the d13C record. But we are still trying to understand the interactions between this changing environment and early metazoan evolution (Bowyer et al., 2024).
Simple compilations of biodiversity changes are insufficient to understand evolutionary dynamics, and ecological and functional traits can tell us more about changing environmental conditions, as well as the changing dynamics of ecological niches, than diversity alone. The Ediacaran-Cambrian Radiation was accompanied by changes in functional traits, which can be understood and analysed even when the affinity of a fossil taxon is unknown. Functional traits are a broad range of organismal attributes which are assumed to influence the communities and ecosystems, such as skeletal type, mineralogy (together representing traits of biomineralization), ecology, and feeding type. Functional diversity can be taken as indicative of ecological complexity, and it has been suggested that taxonomic diversity may tend to increase with the occupation of new areas of functional space as organisms develop novel traits and diversify into newly available niches. Here we will characterise key traits with respect to ecological attributes, interactions and ecosystem functioning (also known as ‘functional diversity’, Mammola et al. 2021). This allows exploration of the decoupling of taxonomic and functional diversity, and the role of functional traits, in concert with the changing oxygenation of the environment. We will focus on the exceptional record of the Nama Group, Namibia.

Key research questions:
1. Is there any relationship between oxygen and the appearance of diversification of new functional traits and ecologies during the early history of animals?
2. Is this independent or related to diversification?

Methodology:
This will consist of three methods:
1. Fieldwork in Namibia will sample well-documented Ediacaran sections that define shelf-to-basin transects within individual sedimentary basins to construct high-resolution profiles, together with palaeontological and lithological distribution data. We will combine the record of macrofossils with these geochemical data within a relative depth framework to interrogate the evolution of seawater chemistry and biotic response through this critical time interval.
2. We will document the local ocean redox dynamics via I/Ca and Rare Earth Elements (REEs).
3. We will compile a dataset of metazoan biodiversity and functional traits through the Ediacaran-Cambrian. Here we will use the package mFD (multifaceted Functional Diversity, in the R environment, Version 2.2.2) which is capable of generating distance-based trait matrices and analysing them using a variety of both dissimilarity-based and multidimensional metrics (Magneville et al. 2022; R Core Team 2022).

Timetable:
Year 1: Compilation of biodiversity and functional traits; Training in R programming, data analysis and development of ecological simulations. Compilation of data for biodiversity analyses, and analysis of biodiversity patterns.
Year 2: Fieldwork in Namibia; initial redox analysis; functional trait analysis; biotic distribution assembly; Completion of ecological modelling work. Biodiversity analyses using compiled data. Laboratory training in geochemical techniques and analysis of samples. Preparation of first manuscript for publication, with support from supervisory team.
Year 3/4: Final redox data acquisition; Dataset integration and analysis; Completion of lab work and simulations, and thesis writing.

Training:
A comprehensive training programme will be provided comprising both specialist scientific training and generic transferable and professional skills. The candidate will join vibrant research group, and receive specialist training in state-of-the-art analytical skills in world class micro-analytical facilities. The student will receive training in palaeontology, carbonate sedimentology and a number of relevant geochemical techniques. All these skills are in high demand in both academia and industry, and will thus provide the student with excellent future employment prospects.

Project Summary:
Global biogeochemical cycling and the rise of animal ecosystems is a focus of international attention, and our research team has the essential specialist expertise to make a major contribution to this topic.

Requirements:
A very good first degree in Geology, or Geochemistry, or GeoSciences, or Biosciences, or other closely-related subject is required. A Master’s degree with an independent research component is desirable.

References:
Bowyer, F., Yilales, M., and Wood, R. 2024. Sea level controls on Ediacaran-Cambrian animal radiations. Science Advances 110, eado6462.
Mammola, S., Carmona, C.P., Guillerme, T. and Cardoso, P. (2021). Concepts and applications in functional diversity. Functional Ecology 35, 1869-1885.
Magneville, C., Loiseau, N., Albouy, C., Casajus, N., Claverie, T., Escalas, A., Leprieur, F., Maire, E., Mouillot, D. and Villéger, S. (2022). mFD: an R package to compute and illustrate multiple facets of functional diversity. Ecography, e05904.