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SUMMARY:The inevitable emergence of density-dependent diffusion in expandi
 ng phage populations - Diana Fusco\, University of Cambridge
DTSTART:20220217T140000Z
DTEND:20220217T150000Z
UID:TALK161527@talks.cam.ac.uk
CONTACT:Jan Behrends
DESCRIPTION:Reaction-diffusion waves have long been used to describe the g
 rowth and spread of populations undergoing a spatial range expansion. Such
  waves are generally classed as either pulled\, where the dynamics are dri
 ven by the very tip of the front and stochastic fluctuations are high\, or
  pushed\, where cooperation in growth or dispersal results in a bulk-drive
 n wave in which fluctuations are suppressed. These concepts have been well
  studied experimentally in populations where the cooperation leads to a de
 nsity-dependent growth rate. By contrast\, relatively little is known abou
 t experimental populations that exhibit a density-dependent dispersal rate
 .\n\nUsing bacteriophage T7 as a test organism\, we present novel experime
 ntal measurements that demonstrate that the diffusion of phage T7\, in a l
 awn of host E. coli\, is hindered by steric interactions with host bacteri
 a cells. The coupling between host density\, phage dispersal and cell lysi
 s caused by viral infection results in an effective density-dependent diff
 usion rate akin to cooperative behavior. Using a system of reaction-diffus
 ion equations\, we show that this effect can result in a transition from a
  pulled to pushed expansion. Moreover\, we find that a second\, independen
 t density-dependent effect on phage dispersal spontaneously emerges as a r
 esult of the viral incubation period\, during which phage is trapped insid
 e the host unable to disperse. Our results indicate both that bacteriophag
 e can be used as a controllable laboratory population to investigate the i
 mpact of density-dependent dispersal on evolution\, and that the genetic d
 iversity and adaptability of expanding viral populations could be much gre
 ater than is currently assumed.\nSee you soon!
LOCATION:Details of video conferencing will be distributed nearer the time
 .
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