Experimental Evolution at Edinburgh
(sex, death and the apocalypse)

Environmental change (led by Sinead Collins)

The process of adaptation is so fundamental to our understanding of biology that it has been studied intensively for over 150 years. Adaptation is one of the most intuitive outcomes of evolution, and evolutionary theory that deals with adaptation sheds light on processes that are intellectually and pragmatically important, such as the evolution of antibiotic and herbicide resistance, the chances of extinction for populations experiencing habitat change, the maintenance of diversity, and the evolution of social interactions. We now have such a clear picture of how adaptation proceeds in simple environments that we can predict the timing and magnitude of fitness increases from de novo mutation in large populations and confirm these predictions by experimental evolution in laboratories. 

We know that global change will dramatically alter marine environments over the next few decades. Global atmospheric CO2 levels have risen from pre-industrial levels of 280ppm to current levels of 380ppm, causing a rise in seawater CO2 concentrations. CO2 levels are expected to reach 750ppm by 2100. As atmospheric CO2 levels rise, the dissolved inorganic carbon (DIC) in oceans increases and causes ocean pH to drop. Ocean acidification is already occurring, and surface water pH is expected to drop 0.4 pH units from pre-industrial levels by 2100. Along with increases in atmospheric CO2 levels, increases in global temperature will increase ocean stratification, which will affect light availability and nutrient upwelling from deeper waters.  In short, the ocean surface environment will undergo drastic and complex changes in the near future. 

Microbes will experience global change as being relatively gradual (spanning hundreds or thousands of generations) and complex, in that several different components of the abiotic environment, as well as the biotic community, will change simultaneously. These facts highlight that an evolutionary approach is required to understand how large microbial populations will respond to global change. Because current theories of adaptation cannot quite deal with all of this yet, I use an experimental model system to expand theory. Generally, I work on how complex environmental change affects the ability of microbes to adapt to high CO2 environments.

 Specific questions that are occupying my mind right now are:

-Can elevated CO2 alone drive evolutionary change in photosynthetic microbes? What about in communities of microbes?

-How does a high- CO2 –evolved algae differ from contemporary algae in terms of carbon uptake and fixation?

-How is gradual environmental change different from sudden environmental change?

-What happens when populations must compete with each other at the same time as they adapt to environmental change?

-What can we learn from natural experiments, such as microbial communities in CO2 springs?