Doctoral Dissertations

Orcid ID

Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Ecology and Evolutionary Biology

Major Professor

Sergey Gavrilets

Committee Members

Louis J. Gross, Orou Gaoue, Shigetoshi Eda


Microorganisms are highly cooperative. Microbial cooperation occurs through the production of costly molecules that provide benefits to individuals in the population. Several mathematical models provide the foundations to understand the microbial evolution of cooperation in surface-attaching populations (biofilms) and in cell-cell communication (quorum sensing). However, while these models assume that goods are fully secreted into the environment, an increasing number of reports have shown that many goods are only partially secreted. This partial privatization of goods (and benefits) was proposed to favor cooperation through one strain producing several cooperative goods or through different strains (each one specialized in producing one type of cooperative good, i.e., through metabolic specialization). In this dissertation, I used a series of individual-based simulations and population genetics models to investigate the effects of partial privatization on the evolution of cooperation in biofilms and on quorum sensing evolution. In chapter 1, I studied whether partial privatization favors the evolution of cooperation in microbial populations living in biofilms. I show that although partial secretion weakens the role that limited diffusion has in fostering cooperation, partial secretion favors cooperation in biofilms. In chapter 2, I studied whether partial privatization favors quorum sensing evolution in unstructured, well-mixed, microbial populations. I found that partial privatization might have been crucial to favor a primordial form of quorum sensing - where autoinducers were thought to be a metabolic byproduct (costless) - but not the transition to costly autoinducers. In chapter 3, I studied whether partial privatization favors quorum sensing evolution in structured microbial populations characterized by limited dispersal of cells and molecules. In this last chapter, I show that: (i) partial privatization favors quorum sensing more than what is possible by kin selection alone; (ii) kin selection and partial privatization may not always be aligned towards favoring the same type of strains; (iii) limited dispersal of autoinducers can redirect which strain is favored by partial privatization. Together, the results presented in this dissertation suggest that partial privatization may generate changes in microbial cooperation not anticipated without its presence.

Available for download on Tuesday, May 15, 2029

Files over 3MB may be slow to open. For best results, right-click and select "save as..."