Evolution in a lab

Claudia Dreifus in conversation with Sinead Collins,who creates evolution in a lab at the University of Edinburgh

When people get algae in their swimming pools or their ponds,they do their best to get rid of it. Why do you deliberately grow it in Scotland?

In my lab,we do something called experimental evolution. Thats a way of trying to figure out how evolution works by observing it. We do that by taking very small creaturesunicellular green algaeand breeding thousands of generations of them in different environments.

With ocean warming and acidification proceeding at an ever-growing pace,we grow the algae in high CO2 environmentswhich is something like what a future ocean might be like. And from this we can get a projection of how they might be in 200 years. Its important to know because microbes such as algae are the starting point of the marine food chain. Of course,were doing this in a laboratory. So its a super-simplified version of a future ocean. Were more trying to figure out the rules reality plays by.

Is experimental evolution new?

No. In the 1880s,there was a guy named the Rev. William Dallinger,and he did an experiment that could be published todayit was that cool. He took microbes that could live only at temperatures under 68 degrees Fahrenheit and over several years evolved them to live at 158 degrees.What is new is applying evolution to current problems. I first came to the field in the 1990s while studying biochemistry at McGill. At the time there were all these super-strains of HIV emerging. That got me interested in how viruses evolve because retroviruses like HIV have this incredibly fast mutation rate. Right away,I could see how experimental evolution was creating tools for understanding the effects of climate change. Who survives in a warmed-up environment? How will they be different from their ancestors? Today I do Dallinger-ish experiments in my own lab. I take the results to an institute in Germany where I help their oceanographers plan their own experiments in real marine environments.

What have your algae taught you so far?

Let me tell you about one experiment we did. There are people who say that all the carbon were putting into the seas might not have a devastating effect. They posit that it wont lead to an over-acidified marine environment which makes sense because many microorganisms are photosynthesisers. They gobble up carbon,use it like food for growth and transform it into oxygen. So to test this,we grew algae in the lab in a high CO2 environment,and 1,000 generations later we saw some really weird syndromes. Some of the algae,if you gave them more CO2,werent storing it anymore. Others photosynthesised many times faster than any of their ancestors had,though they were no longer able to use the extra carbon to become bigger.

What do you make of this?

That this hope that ocean plants will efficiently sop up all the extra CO2 may be overly optimistic. We did another experiment where we found that genetically identical algae evolved differently when they are part of a community than when alone. That means that evolutionary pressure from interactions between algae is stronger than the pressure from ocean acidification. The experiment says that if we want to understand how the oceans will change as we pump more CO2 into them,we need to learn more about the social life of microbes. Evolution always occurs in a community and not in a test tube,and we have to be mindful of that when we create our experiments.