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Biodiversity in the extreme world of Pangea

Dr Alex Dunhill (SEE), Daniel Hill (SEE), Erin Saupe (Oxford), Paul Wignall (SEE)

Contact email: a.dunhill@leeds.ac.uk

Background:

The modern-day latitudinal diversity gradient (LDG) is a keystone ecological pattern based on the decrease in biodiversity from the equatorial to polar regions. Understanding the processes that generate the LDG is critical for predicting the loss of biodiversity as a result of climate change. The fossil record provides a unique record on the evolution and dynamics of LDGs and suggests that the modern-day distribution of biodiversity has not been consistent over the past 500 million years (Mannion et al. 2014).

Figure 1. Distribution of Early Triassic vertebrate fossils showing the response to extreme equatorial high temperature suggesting a bi-model or reverse LDG (Sun et al. 2012).

One period of Earth history where LDGs may have been significantly different to the present is during the late Palaeozoic to early Mesozoic, when the continents were arranged in a single landmass called Pangea. The Permian-Jurassic represents a turbulent period of Earth history with fluctuating extreme icehouse-greenhouse conditions and frequent large-scale volcanic events, resulting in four major mass extinction events (Wignall 2015). The aim of this project is to document how extreme climatic fluctuations and mass extinctions through the Permian-Jurassic influenced LDGs, and to examine which latitudes were most vulnerable to biodiversity loss under extreme climatic stress (e.g., such as the superhot world of the earliest Triassic) (Sun et al. 2012). Such investigations will shed new light on the underlying mechanisms producing latitudinal diversity gradients.

Hypothesis testing:

The student will build a spatiotemporal fossil database, concentrating on tetrapods, marine vertebrates and plants, from a variety of sources (including the Paleobiology Database, the scientific literature, and museum collections) ranging from the Permian-Early Cretaceous. This database will then be used to test the following hypotheses:

1. Pangean LDGs differ from modern LDGs because of harsh, low-latitude conditions.

2. The breakup of Pangea during the Jurassic initiated the establishment of the modern LDG.

3. LDG dynamics are sensitive to high temperature-driven mass extinctions, with preferential extinction occurring at low latitudes.

4. Fossil LDGs can be recreated using climate-constrained LDG simulations.

Impact and publications:

This project will represent a significant contribution to our understanding of how climate change drives the distribution of biodiversity. The work is easily divisible into publications that will form consecutive chapters of the PhD thesis (corresponding to hypotheses 1-4).

An excellent training and research environment: This interdisciplinary project will provide the successful PhD candidate with highly valued and sought-after tools for investigating past climates and macroevolutionary processes. The student will gain experience and expertise in database construction, fossil specimen taxonomy, statistical and spatial modelling, and climate modelling. This skillset will equip the student with the necessary expertise to carry out their own programme of innovative scientific research. The student will benefit from working and collaborating with dynamic scientists in the multidisciplinary Palaeo@Leeds group (Aze, Gill, Gregoire, Haywood, Ivanovic, Little, Lloyd, März, Newton). There will be opportunities to present results at major, international conferences, e.g. IPC, GSA, PalAss, and attend residential summer-schools (e.g. in Australia, USA, UK) and in-house workshops and courses.

Entry requirements:

A good first degree (1 or high 2i), or a good Master’s degree in geological, mathematical, biological or environmental sciences with a focus towards palaeobiology or evolutionary biology, experience in programming (e.g. R, Python) is an advantage but not essential.

Further reading:

Mannion, P. D., P. Upchurch, R. B. J. Benson, and A. Goswami. 2014. The latitudinal biodiversity gradient through deep time. Trends in Ecology & Evolution 29(1):42-50.
Sun, Y. D., M. M. Joachimski, P. B. Wignall, C. B. Yan, Y. L. Chen, H. S. Jiang, L. N. Wang, and X. L. Lai. 2012. Lethally Hot Temperatures During the Early Triassic Greenhouse. Science 338(6105):366-370.
Wignall, P.B. 2015. The worst of times: How life on Earth survived eighty million years of extinctions. Princeton University Press.

Related undergraduate subjects:

  • Biology
  • Environmental science
  • Geology
  • Mathematics