Fig. 3. The relative performance of the Mapping Start Only (MSO) and three versions of the Mapping As You Go approach for nine general classes of genetic models (Table 1). E = the number of different environment types conditioning gene-by-environment interactions in the target population of environments, and K = level of epistasis. Additive genetic models: E = 1, K = 0; Epistatic effects models: E = 1, K = 1, 2; Gene-by-environment effects models: K = 0, E = 5, 10; Epistasis and gene-by-environment effects models: E = 5, 10, K = 1, 2. In all cases, performance is represented as the difference in response between a given breeding strategy and the MSO method. Positive values indicate the breeding strategy had a higher response than the MSO method, and negative values indicate the breeding strategy had a lower response than the MSO method. The performance differences are expressed in terms of normalized trait value.