BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:The effect of selection on genealogies\, and a near-critical syste
 m of branching Brownian motions - Berestycki\, N (Cambridge)
DTSTART:20101122T160000Z
DTEND:20101122T165000Z
UID:TALK28072@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:Consider the following model for the evolution of a population
  undergoing natural selection. At each generation\, individuals give a fix
 ed or random number of offsprings\, whose fitness is perturbed by some ind
 ependent additive noise. Selection maintains the population size fixed by 
 selecting only the fittest individuals.\nPhysicists have recently made som
 e very precise predictions for the genealogy of this population in the lim
 it of inifinite population size\n: namely\, the characteristic timescale i
 s (log N)^3 generations\, and when measured in these units\, genealogical 
 trees are described by the so-called Bolthausen-Sznitman coalescent. These
  predictions build on a non-rigorous analysis of stochastic effects in fro
 nt propagation of KPP equations. We report on some recent progress on this
  issue (joint work with J. Berestycki and J. Schweinsberg)\, where this co
 njecture is shown to hold for a slightly simpler model of branching Browni
 an motions with a suitable cutoff which keeps the population size approxim
 ately fixed.\n
LOCATION:Seminar Room 1\, Newton Institute
END:VEVENT
END:VCALENDAR