Fig. 3. Estimates of the expected total number of individuals n₁ + E(n₂) required in a two generation backcross program (marker distances: ₁ = ₂ = 0.02 M, d₁ = d₂ = 0.10 M) in order to generate with probability q₂ = 0.900, 0.990, and 0.999 at least one BC₂ individual with genotype t⁺ T⁺. The values depend on the probability q₁ of obtaining at least one BC₁ individual with genotype g⁺ G⁺.