The lichen microcosm

Lichen is a fascinating example of successful symbiotic relationships between a fungus and algae. It is also a perfect illustration for endosymbiotic theory, a theory Lynn Margulis greatly contributed to. In this mutualistic relationship, both fungus and algae benefit: fungus obtains energy from the algae that conduct the photosynthesis process while algae are provided with a "home." From an evolutionary perspective, Margulis would argue that lichen is an adaptation that is the result of symbiogenesis (the merging of organisms into new collectives) rather than genetic mutation.
While lichen is made of a fungus and algae, it also provides a habitat for hundreds of bacteria and functions like a micro-ecosystem. Like Margulis, the mycologists interviewed find the micro-ecosystems to be very similar to the eco-systems of the Earth.
While lichen is one of the first organisms to grow in the course of primary succession and requires minimal resources, it appears to be vulnerable to human-made pollution. In Cambridge (MA) lichen has almost disapperead from the old cemeteries. I think lichen disappearance is a clear sign that our urban environment is not fit for human beings either. I also wonder what the evolutionary response to human pollution could possibly be, that is, how microorganisms might be able to cooperate and recombine for increased resilience...

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