Dr Ben Raymond

Research interests

Overview of current research

I am interested in evolutionary biology and evolutionary ecology for its own sake and because of the power of evolution to affect human health and our ability to feed ourselves. 

For example, ongoing natural selection has led to the widespread emergence of resistance to pesticides in insects, a process that continually threatens the sustainability of modern agriculture.  Natural selection has also led to widespread resistance to antibiotics in bacterial pathogens.  The emergence of new infectious diseases and novel virulence factors is also an evolutionary process.  I am interested in these issues because of their shared potential to affect human quality of life.  Theoretically, we have sophisticated and detailed expectations about how natural selection for resistance and virulence should proceed.  I interested in finding out how whether these theoretical expectations are still true in the face of ecological realities.

Field work at Wytham Farm, Oxford. 
B. thuringiensis can be found anywhere there are plants or soil.

I work primarily with Bacillus thuringiensis, a microbe that has been exploited more than any other for the control of insect pests via genetically modified crops and organically-certified microbial sprays.  This species is also closely related to important human pathogens such as Bacillus anthracis, the causative agent of anthrax, and to Bacillus cereus, a bacterium that can induce lethal food poisoning.  Since B. thuringiensis infects only insect hosts, large-scale experiments that explore the basic evolutionary relationships between hosts and pathogens can be readily conducted without the need for infecting mammals.

In scientific terms I try to cross a range of disciplines in order to develop of fuller understanding of microbial evolutionary ecology and of host-pathogen interactions.  Recent work has included the field ecology of microbial pathogens and their hosts, experimental evolution with microbial virulence and insect host resistance, the population genetics of the B. cereus group, and the ecological relationship between insect pathogens and host gut flora.

My current interests are focused more on the testing social evolution theory (kin selection, cooperation) in bacterial pathogens.   Many bacteria, export a significant proportion of their biochemical machinery outside their cell; this may be especially true of pathogens that need to burst open host cells and digest host proteins prior to absorbing/transporting them into the cell.  This creates a scenario in which cells that do not export expensive enzymatic machinery can still take advantage of the machinery produced by others. Social biologists would call these cells “cheats” and their neighbours, that invest in extracellular enzymes, cooperators. Evolutionary biologists have recently made significant contributions to our understanding of the maintenance of many bacterial traits, traits that we define as cooperative.

Bacillus thuringiensis the spores are the blue/grey ovoids and the long blue rods are vegetative cells. The bipyrimidal crystals are primarily composed of insectidal toxins- these provide a group-level benefit to Bacilli in the gut by creating pores in the midgut and allow bacteria to invade the host.

Ongoing work in my laboratory has shown that Bt crystal toxins (the blue crystals in the picture) are produced cooperatively- these are the most important virulence factors in Bt and allow bacteria to invade the host.  Bacterial quorum sensing genes switch on a swathe of extracellular enzymes, many of them virulence factors or proteases. Quorum sensing “cheats” occur at a high frequency in natural Bt population.  Collaborative work with Didier Lereclus and Christine Nielsen LeRoux at will be examining the social biology of quorum sensing within hosts..
Karak in Kuala Lumpur, Malaysia.  A site of intense selection for resistance to Bacillus thuringiensis-based biopesticides...
Research group
 
  • Ms Liqin Zhou
  • Ms Frances Medaney
  • Mr Andrew Matthews

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