Sensitive dependence of fixation probability on life history: The lytic virus case.
by
Zaheerabbas Patwa
University of Western Ontario
Coauthors: Dr. Lindi Wahl (University of Western Ontario)

The fixation probability of a beneficial mutation is the probability with which the allele takes over the entire population. This probability is extremely sensitive to assumptions regarding the organism's life history. We compute the fixation probability using a life-history model for lytic viruses. The model assumes exponentially distributed attachment times and a constant time between attachment and host cell lysis (lysis time). We derive a partial differential equation, including a delay term, which describes the time evolution of the probability generating function (p.g.f.) for the number of individuals in the mutant lineage. By finding the fixed point of this p.g.f., we compute the fixation probability for mutations that increase attachment rate, increase burst size, decrease the lysis time or reduce the probability of clearance. These four mechanisms of mutation give widely varying fixation probabilities. It was found that in all cases, the fixation probability of beneficial mutations was sensitive to the time between population bottlenecks.

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Date received: May 8, 2008