Experimental ecology and evolution in quasi-natural conditions

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The purpose of this research is to decide whether the results of simple laboratory experiments help us to understand processes in large complex ecosystems. The only way in which theories of ecological or evolutionary processes can be decisively tested is through experiments. The problem is that these processes often take place on large scales of space and time. Experiments which require entire lakes, forests or parts of the ocean to be manipulated are laborious, expensive and often impracticable. It is much easier to manipulate microbial communities in small vials in the laboratory, where experiments involving hundreds of communities can be completed in a few weeks or months under highly controlled conditions. For example, whether or not a population will survive in a deteriorating environment may depend on the rate of deterioration, on how variable the population is, and on whether it receives migrants from outside. These factors can all be evaluated in laboratory experiments, but it has been questioned whether the results can be applied to natural systems that are much larger and more complex. My research program will bridge the gap between the laboratory and the field. We have built a research facility in a nature reserve near Montreal to carry out this research. It consists of a secure fenced area holding 96 1000-L experimental ponds and a dedicated laboratory building. The ponds can be fed with water from a nearby lake, so each represents a miniature version of the lake community. We shall use this innovative infrastructure to analyse the phenomenon of evolutionary rescue', which is the process by which a population or community can survive a potentially lethal stress through the spread of resistant types before it becomes extinct. Our main experiment proceeds in two phases. In the first phase, each pond is acidified to a certain level. This lasts for several weeks, giving the community an opportunity to adapt to the stress. In the second phase, every pond is strongly acidified, such that the original community would have been completely wiped out. Laboratory experiments have shown that communities are more likely to be rescued if they have previously experienced a severe but non-lethal stress, or if they are connected to such a community. Our experiment will show whether the laboratory results can be extrapolated to systems that are ten million times larger and contain much more diverse communities. This project and others made possible by the new infrastructure link theory and laboratory work to the field. It is an essential step in understanding and predicting how ecosystems will respond to he stresses they experience through human activities that cause pollution, eutrophication and climate change.