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SUMMARY:Physical Aspects of Evolutionary Transitions to Multicellularity -
  Professor Ray Goldstein (DAMTP\, Cambridge)
DTSTART:20061116T151500Z
DTEND:20061116T154500Z
UID:TALK5256@talks.cam.ac.uk
CONTACT:Duncan Simpson
DESCRIPTION:An important issue in evolutionary biology is the emergence of
  multicellular organisms from unicellular individuals. The accompanying di
 fferentiation\nfrom motile totipotent unicellular organisms to multicellul
 ar ones having cells specialized into reproductive (germ) and vegetative (
 soma) functions\, \nsuch as motility\, implies both costs and benefits\, t
 he analysis of which involves the physics of buoyancy\,\ndiffusion\, and m
 ixing. In this talk\, I discuss recent results on this transition in a mod
 el lineage: the volvocine green algae.  Particle Imaging Velocimetry \nof 
 fluid flows generated by these organisms show that they exist in the regim
 e of very large Peclet\nnumbers\, where the scaling of nutrient uptake rat
 es with organism size is highly nontrivial.\nIn concert with metabolic stu
 dies of deflagellated colonies\, investigations of phenotypic plasticity u
 nder nutrient-deprived conditions\, and theoretical studies of transport i
 n the high-Peclet number regime\, we argue that flagella-generated fluid f
 lows enhance the  nutrient uptake rate per cell\, and thereby provide a dr
 iving force for evolutionary transitions to multicellularity. Thus\, there
  is a link between motility\, mixing\, and multicellularity.
LOCATION:Kaetsu Centre\, New Hall
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