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DTSTAMP:20261019T010848Z
LAST-MODIFIED:20190419T200514Z
DTSTART:20190424T150000Z
DTEND:20190424T160000Z
UID:event2136@bu.edu
URL:http://physics.bu.edu/internal/events/show/2136
SUMMARY:Universality Classes of Evolutionary Dynamics in Expanding Populati
	ons
DESCRIPTION:Featuring Gabriel Birzu\n\nPart of the Departmental Seminars.\n
	\nDissertation Committee:  Kirill Korolev\, Pankaj Mehta\, Shyam Erramilli\
	, Anatoli Polkovnikov\, Andrei Ruckentein\n\nAbstract\nSpatial expansions h
	ave shaped the evolutionary history of many organisms\, from microbes to hu
	mans. These expansions are usually described by two types of reaction-diffu
	sion waves: pulled waves\, which are driven by growth at the edge of the ex
	pansion\, and pushed waves\, which are driven by the bulk. We investigated 
	how demographic fluctuations affect fluctuations in genetic composition and
	 population density when waves transition from pulled to pushed. We showed 
	that the variance of the fluctuations decreases with the population size\, 
	following a logarithmic dependence for pulled waves or a power law dependen
	ce for pushed waves. However\, for weakly pushed waves the exponent is smal
	l and the fluctuations large\, while for strongly pushed waves\, the varian
	ce of the fluctuations decreases inversely proportional to the population s
	ize. Regarding fluctuations in the genetic composition\, the change in scal
	ing is a result of the genealogical structure of the population transitioni
	ng from a Bolthausen-Sznitman to a Kingman coalescent as the wave changes f
	rom pulled to pushed. Importantly\, we found that all of these results are 
	independent of the dispersal and growth models and are controlled by a univ
	ersal parameter: the ratio of the expansion velocity to the geometric mean 
	of the dispersal and growth rates at low density. Thus\, we predict that co
	operative dispersal and growth could have a large impact on evolutionary dy
	namics\, even when their contributions to the expansion velocity is small.
LOCATION:SCI 352\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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