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SUMMARY:Molecular evolution of stochastic switching - Orkun S. Soyer\, Uni
 versity of Exeter
DTSTART:20110408T140000Z
DTEND:20110408T150000Z
UID:TALK30567@talks.cam.ac.uk
CONTACT:Microsoft Research Cambridge Talks Admins
DESCRIPTION:While fitness benefits of phenotypic variance (i.e. stochastic
  switching) under fluctuating environments has been shown both experimenta
 lly and theoretically\, it is not well understood if fluctuating environme
 nts can result in incremental evolution of molecular mechanisms that under
 pin this phenomena. A potential molecular mechanism that can lead to stoch
 astic switching is noisy bistable dynamics in gene regulation. In this tal
 k\, I will summarise results from an in silico evolution study where we ha
 ve simulated molecular evolution of a simple regulatory network consisting
  of a single gene under fluctuating selection on gene expression levels. W
 e find that the main outcome of fluctuating selection is the evolution of 
 increased evolvability in the network\; system parameters evolve towards a
  nonlinear regime where small changes cause large changes in expression le
 vel. In contrast to this broad observation of increased evolvability\, we 
 find that bistability evolves only under environments with specific type o
 f fluctuations and in presence of noise. We find that both evolvability an
 d bistability evolve only in a range of specific environmental fluctuation
  rates\, however\, once evolved they are maintained under a broader range 
 of rates. These results provide the first direct evidence that bistability
  and stochastic switching in a gene regulatory network can emerge as a mec
 hanism to cope with fluctuating environments.
LOCATION:Small lecture theatre\, Microsoft Research Ltd\, 7 J J Thomson Av
 enue (Off Madingley Road)\, Cambridge
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