Prof. Ben Kerr in his lab. Photo courtesy of Ben.

Behavior is an interesting component of life that many consider a human quality.  But there are many types of behavior (e.g., sociality, cooperation, communication) in organisms at all levels of complexity, from unicellular microbes to Homo sapiens. How these different behaviors evolve is an intriguing question. As an undergraduate Ben Kerr took a sociobiology class that piqued his interest in this question and led, ultimately, to a career researching the conditions that drive the evolution of intricate behaviors in different organisms.

After receiving his B.S. from the University of Michigan, Ben took a few years off and traveled to Venezuela with a Fulbright Scholar to study Capuchin monkey communication. Ben found the research exhilarating and it solidified his intent to pursue a career in biology.  However, he realized that conducting research in the field on fast-moving animals came with a suite of practical challenges. So when he started grad school at Stanford he planned to work with ants. 

A yellow lawn of E. coli with clear plaques where viral bacteriophage have caused the E. coli cells to burst. Photo by Roxy Vouk.

Ben was attracted to studying ants for a few reasons. For starters, they can be studied in the lab where highly controlled experiments can be executed. Secondly, their social structure makes them well suited for questions addressing the evolution of social behaviors such as cooperation. However, mid-way through his research at Stanford, Ben attended a seminar in which the speaker discussed microbes. Although most people don’t think of bacteria and viruses as exhibiting behaviors similar to the ones that ants and monkeys exhibit, Ben recognized that on a very basic level they do just that. For instance, microbes help one another by excreting substances that break down food and work together to build multicellular reproductive fruiting bodies. And microbes have one property that ‘macrobes’ don’t have: they evolve quickly.  They are ideal subjects for studying evolution because of their rapid life cycles, not to mention the fact that you can keep a lot of them in a small space. For example, a population of E. coli doubles every 30 minutes and a Petri dish can contain many billions of individuals. Working with microbes such as E. coli allows researchers to watch evolution in real time.

Bacteriophage infecting its E. coli host. Photo courtesy of John Wertz.

One behavioral topic Ben’s lab is currently studying is the evolution of virulence. The central question is, when do pathogens become more virulent, or aggressive, and when do they become more benign? Using E. coli as the host and a viral bacteriophage as the pathogen, Ben’s lab researches how virulence evolves according to the pathogen’s migratory capabilities. The data suggest that when pathogens are able to move from one population to another with relative ease, they can evolve to become more virulent. Pathogens that migrate easily effectively have a large resource pool, because when hosts are exhausted in one population, the pathogen simply moves onto the next. With abundant hosts present there can be selection on the pathogen to enter and exit its host quickly leading to a highly virulent lifestyle. Conversely, pathogens that are restricted geographically only have access to a limited number of hosts and more benign pathogens may persist longer than their less prudent cousins.

In today’s globetrotting society, trans-world shipping routes and flights provide unprecedented migratory opportunities for all sorts of hitchhikers, including pathogens, seeds, and even animals. Ben’s basic research on the evolution of virulence provides theoretical information for how a pathogen’s behavior might change as it is spread around the world. Such knowledge may prove useful to health officials who forecast disease outbreaks, for example, or applied researchers who develop strategies to curb the spread of infection.

In addition to researching the evolution of pathogen virulence, Ben’s lab studies the evolution of various other behaviors, including toxin-production in E. coli, flammability in plants, and learning behavior in animals. Ben joined the UW Department of Biology in the fall of 2005. His lab is a busy place, with five graduate students, ten undergraduates, and a few high school students all conducting research.

For more information on Ben Kerr’s research, visit his website.