E-Thesis 98 views 70 downloads
Functional diversity of sharks through time: past, present and future / JACK COOPER
Swansea University Author: JACK COOPER
DOI (Published version): 10.23889/SUThesis.68819
Abstract
Modern sharks have played multiple roles in marine ecosystems for over 250 million years. Yet, today, overfishing is driving over one-third of shark species towards extinction. Traditionally, scientists assess extinctions by evaluating changes in species diversity. However, the ecology of species de...
| Published: |
Swansea University, Wales, UK
|
|---|---|
| Institution: | Swansea University |
| Degree level: | Doctoral |
| Degree name: | Ph.D |
| Supervisor: | Pimiento, C., and Griffin, J. N. |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa68819 |
| Abstract: |
Modern sharks have played multiple roles in marine ecosystems for over 250 million years. Yet, today, overfishing is driving over one-third of shark species towards extinction. Traditionally, scientists assess extinctions by evaluating changes in species diversity. However, the ecology of species depends on their functional traits, the diversity of which (functional diversity) dictates how species contribute to ecosystem structure and stability. Thus, to understand the ecological consequences of extinctions, it is imperative to record changes in functional diversity. Determining how shark functional diversity has changed through time through their rich, continuous dental fossil record could draw an unprecedented parallel on how extinctions have shaped past, present and future marine communities.First, I assessed the extent to which dental characters can serve as proxies for functional traits in living sharks using a literature review and two validation analyses (chapter 2). This identified seven dental character proxies for body size, prey preference and feeding mechanism, providing a framework to infer these traits from fossil teeth. Second, I investigated changes in functional diversity over the last 66 million years using teeth (chapter 3). This found that shark functional diversity was relatively high for over 50 million years, before declining to its lowest level today over the last 10 million years due to the extinctions of functionally unique and specialised species that inordinately influence ecosystem functioning. Finally, I simulated future shark extinctions and quantified resulting changes in functional diversity (chapter 4). The results projected further declines, and poleward shifting of functional diversity by 2100 and near-worldwide increases in functional uniqueness, rendering virtually all marine habitats functionally susceptible to further extinctions, with the most functionally unique and specialised sharks at greatest risk.Overall, this thesis highlights the importance of prioritising protections for sharks disproportionately contributing to functional diversity to conserve the health of our oceans. |
|---|---|
| Item Description: |
A selection of content is redacted or is partially redacted from this thesis to protect sensitive and personal information |
| Keywords: |
Sharks, functional diversity, teeth, ecological role, extinction, traits |
| College: |
Faculty of Science and Engineering |
| Funders: |
Fisheries Society of the British Isles |