Fig. 1. Direct responses of neutral detergent fiber (NDF) concentration to divergent selection for NDF in four smooth bromegrass populations. Means are over four replicates, three locations, 3 yr, and three harvests. Solid lines represent linear selection responses (b) and dashed lines represent effects of drift (d). R² = 0.99, 0.73, 0.83, and 0.76 for Alpha, WB19e, Lincoln, and WB88S, respectively.