' k v2y terms cancel to give

The final trick is to notice that the series determined by the summation (1 + 1 +---1---1-----1--)

approaches e (e = 2.718...) as k goes to infinity. The summation term can then be replaced with e to give

As promised, the tidy conclusion is that the chance a newly occurring mutant is lost simply due to Mendelian segregation after one generation is e-1 = 0.3679. Therefore, a new mutation has about a 36% chance of being lost within one generation of its introduction into a population. The world is tough for a new mutation!

This result can be extended to determine the probability that a mutation is lost over multiple generations of Mendelian segregation. A general expression for the cumulative probability of a mutation being lost from the population over time is

P(mutant lost generation t) = e

(5.5) where x is the probability of loss in the generation before or at time t - 1. (The series determined by

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