My research

iPhone Pix 235I have explored various research themes throughout my scientific career. What emerges to me upon reflection as tying it all together is my fascination with the magnitude of phenotypic change that is possible across evolutionary timescales: from the evolution of life on earth (I spent hours as a child watching documentaries like BBC’s “Walking with Monsters”, …Dinosaurs, … Prehistoric Beasts), to the maintenance of complex behaviours like cooperation, to the morbidly exciting global evolution experiment that is taking place in the form of climate change. My current focus is on microbial predation and three-level microbial food chains.

I see many possible future directions, such as returning to investigations into the effects of climate change, using bacterial co-evolution to modify drug compounds in response to antibiotic resistance, or applying experimental evolution techniques to studies of the human microbiome in order to understand how our modern lifestyle impacts our microscopic compatriots and to improve human health.

My work on microbial predation: Myxococcus xanthus is a social bacterium that swarms through soil and preys on other bacteria. A previous PhD student in my lab did a predator-prey co-evolution experiment with M. xanthus and Escherichia coli, which showed that each adapted to the presence of the other. But in the wild, M. xanthus is surely not the apex predator of its little ecosystem. What happens when a predator of M. xanthus is added to the mix? How does the risk of predation affect the foraging behavior of a microbial predator? Can M. xanthus’ social behaviors benefit it not only when preying on other bacteria but also when it is itself faced with predation? (PhD… in development)

My work on cheating and cooperation: Much thought has been given to the “Tragedy of the Commons,” or the problem of maintaining cooperation in the face of cheating. For the soil bacterium Myxococcus xanthus, this is an especially pertinent issue because many of its behaviors, such as swarming, predation, and multicellular fruiting body development, require cooperation. In theory, mutants able to cheat on any of these behaviors can arise easily in nature; although to date no cheaters have been isolated from nature, they emerge rapidly during evolution in the lab. There are many hypothesized mechanisms by which cheaters can be prevented from driving cooperative populations to extinction. I have focused on the roles of epistasis and genetic divergence among distinct cooperative groups in restricting the emergence and spread of cheater phenotypes. (Read more)

My work on adaptation to climate change: Carbon dioxide emissions drive ocean acidification, creating a new and challenging environment for many ocean organisms. One such is Emiliania huxleyi, a coccolithophore that is responsible for about 25% of the total carbon sequestered by the ocean each year. Previous work has shown that E. huxleyi, which struggles to produce calcium carbonate scales under acidic conditions, can adapt to the changes predicted for the ocean. However, climate change models predict that the daily fluctuations in dissolved CO2 in regions that experience tidal effects will increase in magnitude, and we can expect that this will also impact organisms such as E. huxleyi. How will E. huxleyi and other key organisms adapt in an environment that is not only changing directionally but also becoming more capricious? (Read more)

 

bacterium in flask