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DTSTAMP:20261018T170722Z
LAST-MODIFIED:20190716T142425Z
DTSTART:20190729T180000Z
DTEND:20190729T190000Z
UID:event2156@bu.edu
URL:http://physics.bu.edu/internal/events/show/2156
SUMMARY:Stochastic Reaction-diffusion Fronts: Applications to Ecology and E
	volution
DESCRIPTION:Featuring Gabriel Birzu\n\nPart of the PhD Final Oral Exams.\n\
	nExamining Committee:  Kiril Korolev\, Pankaj Mehta\, Claudio Chamon (Chair
	)\, Shyam Erramilli\, David Campbell\n\nAbstract:\n\nSpatial expansions hav
	e shaped the evolutionary history of many organisms\, from microbes to huma
	ns. These expansions are usually described by two types of reaction-diffusi
	on waves: pulled waves\, which are driven by growth at the edge of the expa
	nsion\, and pushed waves\, which are driven by the bulk. In my dissertation
	\, I investigate how demographic fluctuations affect fluctuations in geneti
	c composition and population density when waves transition from pulled to p
	ushed. \n\nFirst\, I show that the variance of the fluctuations decreases w
	ith the population size\, following a logarithmic dependence for pulled wav
	es or a power law dependence for pushed waves. However\, for weakly pushed 
	waves the exponent is small and the fluctuations large\, while for strongly
	 pushed waves\, the variance of the fluctuations decreases inversely propor
	tional to the population size. I also show that these scaling regimes are p
	resent in populations with arbitrary density-dependent growth and dispersal
	.\n\nSecond\, I show that the different rates of genetic diversity loss in 
	the different classes of waves are a result of the genealogical structure o
	f the population transitioning from a Bolthausen-Sznitman to a Kingman coal
	escent as the wave changes from pulled to pushed. Importantly\, all of thes
	e results are independent of the dispersal and growth models and are contro
	lled by a universal parameter: the ratio of the expansion velocity to the g
	eometric mean of the dispersal and growth rates at low density. Thus\, coop
	erative dispersal and growth could have a large impact on evolutionary dyna
	mics\, 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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