• Testing the assumptions of the natural laboratory paradigm – the idea that islands are ideal model systems for studying evolution
• Using archival collections in novel ways to address novel questions
• Multidisciplinary training integrating aDNA work at University of Warwick with herbarium and field-based research at the Natural History Museum.
Oceanic islands have long been recognised as ‘natural laboratories’, ideally suited for in-situ studies of evolution. They provide some of the most striking, text book examples of adaptive radiations and have played – and continue to play - a major role in the development of key concepts in biology. At the same time, their biota, that are so rich in unique diversity, are also among the most globally endangered. In the Azores, for example, it is estimated that less than 10% of the native forest at the time of colonisation in 1439 survives whilst in the Canaries and in Easter island, palaeoecological data points to pre-historic, human-mediated extinction of dominant tree species. More recent records of extinction – backed by specimens in museums and herbaria - are known from many oceanic islands worldwide.
Developments in molecular biology, notably the development of Next Generation Sequencing techniques (NGS) have the potential to greatly extend the scope of studies on ‘island laboratories’ to encompass fundamental questions relating to the genetic basis of island diversification events. The acquisition of DNA sequence data at the genomic level is providing unprecedented opportunities to uncover the history of lineages in non-model organisms. It is allowing us to elucidate evolutionary relationships in rapidly evolving island lineages that were previously intractable and to start to understand the genomic basis of speciation events, to determine the number of loci involved in speciation, the nature of the genetic differences, and what those loci control.
However, the ‘natural laboratory’ paradigm assumes that diversity patterns on islands are the result of natural ecological and evolutionary processes. It assumes that the impact of humans is not significant for the interpretation of those patterns. Is that a valid assumption? Given the scale and breadth of human impact on oceanic islands, this project aims to test this assumption of the natural laboratory paradigm across a spectrum of evolutionary questions.
We propose to test the assumptions of the natural laboratory paradigm using the floras of St Helena. There are classic examples of evolutionary processes such as adaptive radiation; humans have had a profound impact on their biota and there is a history of botanical collecting spanning the last three hundred years, a period of profound change. We will focus the study on Trochetiopsis in St Helena.
Next generation sequencing coupled with ancient DNA techniques will be used to generate data from both living and herbarium material for these evolutionary radiations. We will contrast inferences based only on living material with those also incorporating archival samples. This will allow us to elucidate the impact of range reductions and extinctions on phylogenetic and phylogeographic questions at different scales – from broad scale sister taxon relationships of island clades to population-level analyses.
Training and skills
CENTA students are required to complete 45 days training throughout their PhD including a 10 day placement. In the first year, students will be trained as a single cohort on environmental science, research methods and core skills. Throughout the PhD, training will progress from core skills sets to master classes specific to CENTA research themes.
This project is multidisciplinary in nature. At Warwick, the student will receive training in the generation of NGS data and the analysis of those data to address phylogenetic and phylogeographic questions. Integration of historic herbarium material in those analyses will be integral to the training provided. At the Natural History Museum, the student will develop expertise in island plant taxonomy, evolution and biogeography and will receive training in fieldwork and in herbarium-based research.
Partners and collaboration
This project is a collaboration between the University of Warwick and the Natural History Museum, London (NHM).
At Warwick Robin Allaby leads the plant ancient DNA group specializing in archaeogenomics and genome evolution. https://warwick.ac.uk/fac/sci/lifesci/people/rallaby/
At the NHM, Mark Carine is the lead curator for the botanical collections and a plant systematist with particular interests in island floras and biogeography. His research has been addressing taxonomic problems, biogeographic patterns and speciation processes in a number of taxa and island systems in the Atlantic. http://www.nhm.ac.uk/our-science/departments-and-staff/staff-directory/mark-carine.html