Biol Direct. 2011 Apr 14;6:20. PubMed; doi 10.1186/1745-6150-6-20

On the relationship between the load and the variance of relative fitness.

Shnol, E. E.; Ermakova, E. A.; Kondrashov, A. S.

BACKGROUND: Operation of natural selection can be characterized by a variety of quantities. Among them, variance of relative fitness V and load L are the most fundamental. RESULTS: Among all modes of selection that produce a particular value V of the variance of relative fitness, the minimal value L min of load L is produced by a mode under which fitness takes only two values, 0 and some positive value, and is equal to V/(1+V). CONCLUSIONS: Although it is impossible to deduce the load from knowledge of the variance of relative fitness alone, it is possible to determine the minimal load consistent with a particular variance of relative fitness. The concept of minimal load consistent with a particular biological phenomenon may be applicable to studying several aspects of natural selection.