How is biodiversity generated and maintained: identifying the mode and drivers of diversification at the macro-scale

We are seeking a highly motivated individual to carry out PhD research in the field of evolutionary ecology. The successful candidate will split their time between the University of Stirling (UofS, Biological & Environmental Sciences) supervised by Dr Lynsey Bunnefeld and the University of Groningen (UofG, Institute for Evolutionary Life Sciences) supervised by Prof. Rampal S. Etienne. Dr. Alex Pigot from University College London will also be central to project development and supervision.

At a time when rapid global environmental change is increasing species’ extinction risk, gaining a better understanding of how species diversity is generated and maintained will put us in a stronger position to conserve it into the future. However, understanding the processes regulating the diversity of life on Earth is a major challenge in biology. Molecular phylogenies present an opportunity to distinguish between several potential processes, For example, a remarkable pattern revealed by molecular phylogenies is that rates of species diversification appear to slow down towards the present.

Various models have been proposed to explain this slowdown and the dynamics of diversification. Two prominent examples are diversity-dependent and protracted speciation. The first assumes a limit to the number of species per species group, while the latter models speciation as a prolonged rather than instantaneous event – both giving the impression of a slowdown in species accumulation towards the present. Both models are intuitively appealing: the former suggests diversity can saturate - the world can ‘fill up’ - while the latter highlights that speciation is not often instantaneous, phenotypic divergence and reproductive isolation among incipient species takes time to build up (and can collapse). However, we do not rule out alternative models.

In this project, we will determine when different models (and particularly diversity-dependent and protracted speciation) can be robustly distinguished and, using extensive datasets collated from the literature, we will determine the ecological and environmental factors associated with different modes of diversification across a range of taxa. In this way, we will be in a stronger position to predict likely winners and losers in the future and take measures to mitigate potential losses.

The project has three main aims to: (i) use extensive simulations to determine how well these models are capable of detecting and differentiating speciation scenarios; (ii) apply these methods to real phylogenies to gauge the power of the modelling framework to explain patterns observed in empirical data; (iii) seek correlations between model parameters and empirical environmental and ecological variables that are likely to affect diversification.

This is an ambitious project that has the scope to substantially alter our understanding of macroevolutionary clade dynamics. The candidate will also have the opportunity to shape the direction of the project in conjunction with the supervisory team, for instance extending models to incorporate species interactions or community dynamics through time.

Project specifics

This project will suit a quantitatively-minded student with a background in the biological or mathematical sciences. This is a Big Data project and will involve training in several important transferable skills: data management (the candidate will learn how to manage large datasets efficiently and securely), modelling (the candidate will become experienced with complex regression and simulation modelling techniques) and numeracy (important throughout for managing and assessing available data and models). Our team of supervisors is excellently placed to provide the relevant training and has a complementary range of experience and expertise across a range of taxonomic groups and analysis techniques.

Specifically, Dr. Lynsey Bunnefeld is experienced in simulation modelling techniques and in the management and analysis of large macroecological and macroevolutionary datasets. Further, Prof. Rampal Etienne proposed the diversity-dependent and protracted speciation models for explaining diversification patterns observed in phylogenies and has developed likelihood-based methods to test and apply these new models to biological data. Finally, Dr. Alex Pigot has access to and extensive experience with large empirical databases. Together, we have worked on a range of animal and plant taxa and have published extensively on the topics of macroevolution and diversity dynamics.

The student will be jointly registered at UofS and UoG and will divide his/her time equally between the Evolutionary Ecology group at UofS and the Theoretical & Evolutionary Community Ecology group at UofG.

The position is open to UK and EU citizens and we invite all excellent candidates to apply.