Cooperation in biofilms
“(O)ur theory predicts for clones a complete absence of any form of competition which is not to the overall advantage and also the highest degree of mutual altruism. This is borne out well enough by the behaviour of the clones which make up the bodies of multicellular organisms. However, when we consider populations of free-living asexual organisms there appears to be a discrepancy in that competitive adaptation is hardly less conspicuous than it is for most wholly sexual populations and altruism if it exists, is not easily detected.” -William Hamilton, 1964
Recent decades have seen a dramatic increase in our knowledge of the profound degrees of communication, coordination, and cooperation in bacterial communities, particularly biofilm communities. The ubiquity of the biofilm mode of life in nature, and of the general biofilm strategy across the diversity of microbial life, suggests that some degree of cooperation is likely the rule, rather than the exception, in what were previously believed to be the very simplest organisms. It is interesting, from this historical perspective, that Hamilton (quoted above) took such great pains in the second half of his seminal 1964 work to try to explain what was at the time believed to be a lack of cooperation among microbes.
My work has included theoretical and empirical approaches to understanding the interplay between diffusion rates, neighborhood size, and the evolution of the production of extracellular, beneficial metabolites in bacteria.
A 3D reconstruction of a developing biofilm comprised of Pseudomonas chlororaphis strain 30-84 wild type (red) and a gacA regulatory mutant (green).
Driscoll, W.W., Pepper, J.W., Pierson, L.S., and Pierson, E.A. (2011) Applied and environmental microbiology 20: (TBD).
Driscoll, W.W. and Pepper, J.W. (2010) Evolution 64: 2682-2687.