Final answer:
The selection differential for a quantitative trait is the difference between the mean for the trait in the original population and the mean of those individuals that reproduced. A larger selection differential indicates that there will be more change in the trait in the next generation, particularly if the trait has high heritability, influencing the evolution of the population.
Step-by-step explanation:
The selection differential for a quantitative trait is b) the difference between the mean for the trait in the original population and the mean of those individuals that reproduced. Assuming heritability is the same in all cases, a larger selection differential means there will be more change in the trait in the next generation. Heritability is important in this context because it indicates the fraction of phenotype variation that can be attributed to genetic differences among individuals in a population. If a trait has high heritability, it is more likely that the offspring will exhibit the selected traits. The greater the heritability, the more profound the impact of selection on the evolution of the population.
Selection differential is crucial for both artificial selection and natural selection, as these mechanisms rely on the differential reproduction of individuals with favorable traits. Accordingly, if the selection differential is large, it indicates that the selected traits have a significant departure from the population mean, suggesting a stronger selection pressure towards those traits. Over time, this can lead to an appreciable shift in the population's phenotypic distribution.