Evolution in the sea: how do new phytoplankton species form?

Photosynthesis in marine phytoplankton is responsible for about half of newly produced organic matter on the planet. The amount of CO2 fixed by phytoplankton is thought to significantly affect the global carbon cycle and climate. Yet, surprisingly little is known about how new plankton species originate and adapt to ever changing environment. While evolutionary process in terrestrial populations have been actively studied in many animal and plant species, little is known about population genetic processes underpinning adaptation and speciation in astronomically large populations of marine plankton species. To address this gap in our knowledge, this project will combine fossil and climatic records from the late Quaternary with genome-wide evolutionary genetic analyses of adaptation and speciation in a major group of oceanic phytoplankton, the coccolithophores (Haptophyta).

The calcifying coccolithophores (Haptophyta) represent an excellent model group to study the evolutionary processes underlying plankton speciation by integrating genomic, biological, biogeographic and palaeontological data. This group comprises around 200 well-described extant species which are widely distributed in modern oceans. Coccolithophores form calcium carbonate scales, called coccoliths, which have complex and distinct architectures (see figure), allowing identification of morphospecies in extant diversity and the fossil record. Since their appearance around 220 Ma, coccoliths have formed massive calcareous deposits (e.g. the White Cliffs of Dover in southeast England) that provide an enormously abundant and essentially continuous fossil record for this plankton group. This project will focus on the most abundant family of coccolithophores, the Noëlaerhabdaceae, including Emiliania huxleyi that first appeared in fossil record only ~290 thousand years ago, but is ubiquitous and so abundant in the modern oceans that its blooms are visible from space. The availability of E. huxleyi genome, detailed fossil record, extensive culture collection of strains sampled across the globe, and the record of global climatic oscillations in late Quaternary make this system an ideal evolutionary genetic model to study adaptation and speciation processes in marine phytoplankton.

As much of the data for this project is already available, the project will primarily focus on computational evolutionary genetic analysis of genome sequence data, but may include some lab-based work, if desired by the student. This interdisciplinary project offers an opportunity for interactions with evolutionary geneticists, ecologists, marine biologists, palaeontologists and ocean biogeochemists, which will expose the student to new ideas in different fields and provide rich and stimulating environment.

STUDENT PROFILE

Necessary: Strong interest in evolutionary genetics and good bioinformatic skills.
Desirable: Previous experience with Linux environment and some programming skills.