In statistics, what does selection change?

In statistics, what does selection change?

• A. The variance only
• B. The maximum possible value
• C. The genetic mechanism directly
• D. The average value of a trait

Answer: (D)

Selection changes the average value of a trait. By favoring individuals with certain trait values (for example, those with higher height or higher yield), you bias the distribution toward those values. This shifts the population mean upward or downward, depending on which individuals are selected. In breeding terms, the difference between the mean of the selected parents and the overall population mean is the selection differential, and the expected change in offspring’s mean is proportional to this differential (R = h^2 S), showing how the average value moves toward the selected phenotypes. Variance or the maximum possible value aren’t the primary, guaranteed effects of selection in this context, and the action isn’t about a direct genetic mechanism changing by itself.

Selection changes the average value of a trait. By favoring individuals with certain trait values (for example, those with higher height or higher yield), you bias the distribution toward those values. This shifts the population mean upward or downward, depending on which individuals are selected. In breeding terms, the difference between the mean of the selected parents and the overall population mean is the selection differential, and the expected change in offspring’s mean is proportional to this differential (R = h^2 S), showing how the average value moves toward the selected phenotypes. Variance or the maximum possible value aren’t the primary, guaranteed effects of selection in this context, and the action isn’t about a direct genetic mechanism changing by itself.