This says that genetic drift reduces genetic variation by an amount equal to the inverse of twice the effective population size every generation, due to sampling error. (This same conclusion can be reached using the approach of consanguineous mating, as shown in section 3.5.) This rate of loss of genetic variation can clearly be seen in Fig. 3.9, where the frequency of genetically variable populations (those with one A allele) halves each generation since the population size is one. This result applies to any population size and shows us that the effects of genetic drift relate directly to the size of a population.

Markov chain A sequence of discrete random variables in which the probability distribution of states at time t + 1 depends only on the states at time t.

Markov property Probability of a given outcome in the next step or time interval depends only on the present state and has no "memory" of states or events before the present time.

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