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COMPLEX TIME: Adaptation, Aging, & Arrow of Time

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Irreversible Processes in Ecological Evolution/Cooperative growth and cell-cell aggregation in marine bacteria

From Complex Time

January 29, 2019
2:30 pm - 3:30 pm


Otto Cordero (MIT)


Bacterial cooperation, whereby cells secrete compounds that can facilitate the growth of neighboring cells, has been extensively studied through the lens of evolutionary biology. However, the environmental implications of cooperation and the ecological scenarios under which it takes place remain much less understood. In this talk I will discuss the conditions under which cooperative growth emerges in microbial populations that degrade complex organic materials in the ocean. I will show that organisms that are poor secretors of hydrolytic enzymes use chemotactic behavior to form cell-cell aggregates that enable individuals to increase local concentrations and efficiently uptake the solubilized organic matter. By contrast, when organisms secrete highly active enzymes dynamics turn competitive, cells avoid aggregation and the efficiency of carbon uptake drops. I will also discuss the theoretical limits of aggregation and how bacterial isolates from the ocean overcome these limits in the laboratory by developing multicellular behaviors. I will back up these results with theory, data from individual based models and experiments with natural isolates. Finally, I will discuss the potential role of social cheaters in the natural environment, based on a study with hundreds of micro-scale particle colonization experiments in natural seawater.

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