Date of Award

Summer 2010

Project Type


Program or Major


Degree Name

Doctor of Philosophy

First Advisor

Vaughn S Cooper


Many biofilm populations are known for their exceptional biodiversity but the relative contributions of the forces that could promote this diversity are poorly understood. This uncertainty pervades in the well-established communities found on many natural surfaces and in long-term, chronic infections. Here we describe the parallel evolution of cooperative communities derived from a clone of Burkholderia cenocepacia during approximately 1500 generations of biofilm selection. This long-term evolution was enabled by a new experimental method that selects for daily cycles of colonization, biofilm assembly, and dispersal. Each of six replicate biofilm populations underwent a common pattern of adaptive morphological diversification, in which three ecologically distinct genotypes arose in the same order of succession and persisted. Mixed communities were more productive than any monoculture and each variant benefited from mixture. These gains in output resulted from asymmetrical cross-feeding between genotypes and the expansion and partitioning of biofilm space that constructed new niches. Furthermore, the diversity found in these was due to unique mutations found in each morphotype detected by complete genome sequencing.