TABLE 1 .

Key terms used in this article

Term	Definition
Effective population size (Ne)	This is the size of an ideal population, in which all individuals reproduce equally and experience no fluctuation in size, which experiences the same genetic drift as the actual population. It is typically calculated as the harmonic mean of the population sizes at the time of transfer and the fraction that is transferred, which is strongly biased toward the bottleneck size.
Selective coefficient (s)	The fitness difference between a given genotype and typically, a wild-type genotype, in units of time−1. Commonly in experimental evolution, s is defined as the difference in Malthusian parameters between the mutant and wild type as follows: ln (Nm1/Nm0) − ln (NWT1/NWT0), where N is cell number and m is mutant and WT is wild type at time 0 or 1 (e.g., Nm1 is the number of mutant cells at time 1).
Establishment	The process whereby a mutation rises to a high enough frequency to escape loss by drift, i.e., greater than experimental population bottlenecks and greater than 1/s.
Clonal interference	Competition between beneficial mutants in an asexual population resulting in the loss of less beneficial mutants and the delayed rate of fixation of the most beneficial mutant (10). Also known as the Hill-Robertson effect in sexual populations, where the process may be overcome by recombination that assembles beneficial mutations within the same genome (41).