PhD project: Island biogeography through the lens of a geologist

The Department of Earth Sciences is seeking an enthusiastic candidate for a PhD project that aims to reconstruct island environments over millions of years to understand differences in biodiversity on different islands across the globe.

Your job
Since the days of Darwin and Wallace, islands have played a crucial role in the development of theories and hypothesis on the origin and evolution of species. Islands, being isolated, discrete, and numerous, provide a suite of natural laboratories that can be used as simplified model systems of the natural world. Island biogeography, the field of study of the geographic distribution of life's diversity, specifically on islands, has traditionally been occupied by biologists. In the classical Theory of Islands Biogeography, which focuses on volcanic hotspot islands, MacArthur & Wilson (1967) postulate that insular species richness is correlated with island size and isolation from the continent. Inspiring many decades of research, this theory - one of the most cited theories in biology - has proven to be a powerful framework for understanding the ecological processes acting on populations of species on islands. However, this theory does not take evolutionary time into account, nor does it acknowledge that island environments and their biota are dynamic through time.

In recent years, it has been recognised that island biodiversity does not only depend on present day variables such as area and isolation, but that the geological history of islands plays a key role as well. In particular, island biodiversity is thought to vary throughout the lifespan of an island, with immigration, speciation and extinction rates varying over the buildup (by volcanic activity) and subsequent collapse (by erosion) of the island. This makes island age a key parameter. However, determining such an age is complex, and requires detailed mapping and dating of all volcanic rock units on an island, whereby the age of the oldest volcanic rocks is then interpreted to reflect island age. Such data is available for a few, very well studied hotspot islands, such as the islands of Hawaii and the Canary Islands. However, even if such data is available, the age of the oldest mapped volcanic rock will only provide a minimum age of the island, as older volcanic units may be unexposed or buried beneath younger volcanic units.

Moreover, it has been recognised that different island types (hotspot, but also for example subduction-related volcanic arc, rifted continental fragments, or continental shelf islands) have very different geological histories, very different starting points for life (barren vs. populated) and very different isolation histories (with for example on and off connectivity to the mainland during ice ages for continental shelf islands). Approaching this topic from a geological perspective and integrating these complexities into island biogeography theory is a major next step in this field.

The aim of this project is to explain the differences in biodiversity (species richness and composition of species assemblages) on different islands across the globe, to understand how biodiversity is shaped, over millions of years, by Earth's environment and changes therein. Studying islands and insular biodiversity enables comparing different natural laboratories, with islands of different ages and with different types of dynamic environments leading to different types of biodiversity. As such, patterns and trends may be discerned regarding the co-evolution of Earth and life.

The objectives of this PhD project are the following:

• Dating volcanic islands

In this project, we will test a novel method for dating volcanic islands: through zircon dating of beach sands. Ages of zircon grains in beach sands are expected to provide constraints on the moment of island emergence, and, in the case of an inactive volcano, when volcanic activity ended. This record is expected to be more complete than what can be extracted from volcanic rocks that are currently exposed on an island, as older volcanic units may be buried or otherwise unexposed. We will first collect data from well-studied islands from which ages are known, and when proven successful, use this method to date more volcanic (hotspot, and potentially also arc) islands. Fieldwork locations are to be determined, but will likely include the Canary islands and Hawaii.

• Compiling island parameters
  
  • build a database of islands, whereby the islands are subdivided into categories that are based on geological characteristics, but that are relevant for biology.
  • compile published and newly determined island ages, including uncertainties.
  • analyse the differences between the types of islands in terms of age, elevation, topography and size.
  • develop generalised models of geological island evolution ("island ontogeny") for the different island types, describing size, isolation, elevation, and topography through time.
• Analysing biodiversity metrics
  
  • Compile data for various biodiversity metrics (species richness, phylogenetic diversity, phylogenetic endemism, paleo/neo-endemism) for a subset of selected islands.
  • Analyse biodiversity metrics in relation to island type, island age, and island ontogeny.

You are expected to publish your results in peer-reviewed academic journals as Open Science contributions. A personalised training programme will be set up, reflecting your training needs and career objectives. About 20% of your time will be dedicated to this training component, which includes training on the job in assisting in the Bachelor’s and Master’s programmes of the Department at Utrecht University.

Requirements:

As the ideal candidate, you have an interdisciplinary mindset and are not afraid to branch out into new fields, learn new skills, and communicate with multiple different communities of researchers. Furthermore, you have:

• a Master’s degree in Earth Sciences (geology, geophysics, geomorphology, volcanology, or a related field), ultimately obtained at the start of the position;
• affinity with, or interest in, biodiversity/biogeography;
• enthousiasm for (and the ability to perform) geological fieldwork and the organisation thereof;
• excellent skills in writing and speaking English (C1 level).

If you already have a PhD degree, unfortunately, we cannot consider you for this position.

Salary Benefits:

We offer:

• a position for one year, with an extension to a total of four years upon a successful assessment in the first year, and with the specific intent that it results in a doctorate within this period;
• a working week of 36 hours and a gross monthly salary between € 2.770,- and € 3.539,- in the case of full-time employment (salary scale P under the Collective Labour Agreement for Dutch Universities (CAO NU));
• 8% holiday pay and 8.3% year-end bonus;
• a pension scheme, partially paid parental leave and flexible terms of employment based on the CAO NU.

In addition to the terms of employment laid down in the CAO NU, Utrecht University has a number of schemes and facilities of its own for employees. This includes schemes facilitating professional development, leave schemes and schemes for sports and cultural activities, as well as discounts on software and other IT products. We also offer access to additional employee benefits through our Terms of Employment Options Model. In this way, we encourage our employees to continue to invest in their growth. For more information, please visit Working at Utrecht University.

36 - 40 hours per week

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