What are the ecological rules that govern microbial behavior and evolution?

What can modern Earth microorganisms teach us about the biogeochemistry of the early Earth and signatures of life on other planets?

"My mitochondria comprise a very large proportion of me...I suppose there is almost as much of them in sheer dry bulk as there is the rest of me. Looked at in this way, I could be taken for a very large, motile colony of respiring bacteria, operating a complex system of nuclei, microtubules, and neurons for the pleasure and sustenance of their families, and running, at the moment, a typewriter."

----Lewis Thomas, The Lives of a Cell, 1974