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UID:9ad8b344f4f3a2192cc4242b7b959217
CATEGORIES:Mathematical Physics Seminar
CREATED:20230118T093229
SUMMARY:Evolution in changing environments and driven disordered systems
LOCATION:Zoom
DESCRIPTION:<p style="background: white; text-align: left;">Abstract :&nbsp;Biological 
 evolution is governed by the fitness landscape, a map from the genetic sequ
 ence of an organism to its fitness. &nbsp;Here fitness denotes some quantit
 ative measure of reproductive success, such as the expected number of offsp
 ring. A fitness landscape depends on the organism's environment, and evolut
 ion in changing environments is still poorly understood. After introducing 
 the concept of fitness landscapes and their mathematical description, the t
 alk will focus on a particular model of antibiotic resistance &nbsp;evoluti
 on in bacteria, where the drug concentration is an environmental parameter.
  Tradeoffs between adaptation to low and high concentration lead to a rugge
 d landscape with an exponentially large number of fitness peaks. With evolu
 tionary dynamics that follow &nbsp;fitness gradients, resistance evolution 
 under slowly changing antibiotic concentration resembles the zero temperatu
 re dynamics of &nbsp;a disordered spin system under quasistatic driving. Sp
 ecifically, the set of genetic sequences that form a fitness peak at some c
 oncentration maps exactly to the metastable states in an equivalent Preisac
 h system, a paradigmatic model of hysteresis in random &nbsp;magnets. Makin
 g use of the conceptual tool of state transition graphs developed in the co
 ntext of driven disordered systems, we quantify the degree of genotypic and
  phenotypic reversibility in the response of the population to antibiotic c
 oncentration &nbsp;cycling, and ask to what extent a memory of past concent
 ration changes is stored in the current genetic sequence. The talk is based
  on joint work with Suman G. Das and Muhittin Mungan.</p>
CONTACT:Joachim Krug - University of Cologne
DTSTAMP:20260826T213940
DTSTART;TZID=America/New_York:20230118T104500
DTEND;TZID=America/New_York:20230118T114500
SEQUENCE:0
TRANSP:OPAQUE
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