We observed a similar sweep of DFTD tumors on the Forestier Peninsula.
Weak selection/fast fluctuation limit: When the duration of a sweep becomes much longer than the period of population-size fluctuations, the probability of observing a soft sweep converges to that expected in a population of constant size, given by the harmonic mean of Ne(t) estimated over a population cycle (dash dotted line in Figure 4B).
Strong selection/slow fluctuation limit: When the duration of a sweep becomes much shorter than the timescale over which population size changes, the probability of observing a soft sweep in the cyclical population model converges to that which is expected in a population of constant size Ne t0), the effective population size at the starting time of the sweep.
Strong selection/slow fluctuation limit: When the duration of a sweep becomes much shorter than the timescale over which population size changes, the probability of observing a soft sweep in the cyclical population model converges to that which is expected in a population of constant size N e(t 0), the effective population size at the starting time of the sweep.
For a weakly selected allele in a population that fluctuates much faster than the duration of the sweep, it will be close to the minimum size encountered during the sweep, resulting in a low effective population size and, correspondingly, a low probability of observing a soft sweep.
The minimum diversity is observed when a sweep has driven most competing ancestor strains to low frequency.
Students observe that most flies have red eyes, and these red-eyed flies have lost variation at the near marker but maintained variation at the far marker hence observing a "selective sweep" and the "hitchhiking" of a nearby neutral variant.
The effective population size remains large in this case, increasing the probability of observing a soft sweep.
Again we see that even for the same demographic scenario, the probability of observing a soft sweep can vary dramatically with selection coefficient.
For each starting time we calculate the expected probability Psoft,2 t0, s) of observing a soft sweep in a sample of size 2 as a function of the selection coefficient (s), of the adaptive allele, assuming that the population is sampled when the adaptive allele has reached population frequency x = 1/2.
