The history of this secondary invasion has involved bottlenecks and has been followed by accumulation of new mtDNA variation.
We postulate that the factors involve possible bottlenecks in service provision over weekends and after office hours.
Practical production scheduling problems usually involve some "bottleneck" machines, the scheduling policies for which could significantly affect the final solution quality.
That year, the problem involved railroad bottlenecks in getting coal to power plants — an issue largely resolved with the subsequent investments in more rail lines.
First, continued evolution of R5 viruses in PBMCs, spleen and lymph nodes involved multiple bottlenecks, independent of coreceptor switch, resulting in fitter quasispecies driven by positive selection.
This assumed demography, involving periodic bottlenecks where the number of individuals is fixed, is typical of most experimental setups, where daily passages of a sample of the population are performed, and population numbers are experimentally controlled.
However in spite of recent successes, the path to a high-resolution structure of a membrane protein still involves several bottlenecks including poor expression, limited extraction success, low purification yields and paucity of well-ordered 3D crystals (Fig. 1).
A transmission event involves a bottleneck: N B cells are randomly sampled from the host and passed to the susceptible individual.
However, this was likely to be rare since phage densities only approached those of hosts late during flask growth, and each transfer involved a bottleneck to a smaller population size such that co-infected hosts would be subject to strong sampling effects.
Introduction events may involve a population bottleneck because the number of initial colonists is often small [18], [23].
