Scheme: Dorothy Hodgkin Fellowship
Organisation: University of Bristol
Dates: Jan 2012-Dec 2016
Summary: Co-evolution of photosynthesis and the biosphere
Cyanobacteria (known as blue-green algae) transformed the atmosphere during the early Earth. They were the first organisms to perform oxygenic photosynthesis, and in doing so released large amounts of oxygen into the air. By performing photosynthesis these microorganisms released large amounts of oxygen into the atmosphere, thus enabling the development of complex life. My aim is to understand how cyanobacteria have contributed to the Earth’s global nutrient cycles (e.g. nitrogen, oxygen and carbon) making our planet increasingly habitable.
My work has shown that cyanobacteria capable of creating soluble nitrogen ‘fertilizer’ directly from the atmosphere diversified and spread throughout the open ocean around 800 million years ago. This event gave the Earth’s ocean a huge boost in primary productivity and it changed forever how carbon was cycled in the ocean. The timing of the spread in nitrogen fixers in the open ocean occurred just prior to global glaciations and the appearance of animals.
My findings have implications to understanding when the appearance of complex multicellular life was first made possible. It has been long believed that animals evolved towards the end of the Precambrian (the geologic interval lasting up until 541 million years ago) due to an increase in oxygen, as revealed in the geological record. But, it has remained a mystery as to why oxygen increased at this particular time and what its relationship was to 'Snowball Earth' – the most extreme climatic changes the Earth has ever experienced – which were also taking place around then. It has become clear that evolutionary events in cyanobacteria have helped transformed our Earth System making our planet habitable. As primary producers in today’s oceans they play a key role regulating long term climate change, therefore studying them gives us clue as to how nutrient cycles interact with our planet.