Question

How is the response to selection of a trait calculated?

1) By calculating the phenotypic frequencies of the phenotypes.
2) By multiplying the heritability by 100.
3) By dividing the value of the parental phenotype by the standard deviation.
4) By multiplying the strength of selection by the heritability.

Answer 1

The response to selection of a trait is calculated by multiplying the strength of selection by the heritability. Thus the correct Option is (4).

Step-by-step explanation:

The calculation involves two key factors: the strength of selection (S) and the heritability (h²). Strength of selection represents the intensity with which a trait is favored or disfavored in a population. Heritability is the proportion of phenotypic variation that is attributable to genetic factors. The formula for calculating the response to selection (R) is given by R = S * h².

To break it down further, the strength of selection (S) is the difference in the mean trait values between the selected parents and the entire population. It is crucial because it determines the direction and magnitude of the change in the trait under selection. Heritability (h²) quantifies the genetic contribution to the observed phenotypic variation. It ranges from 0 to 1, where 0 indicates no genetic contribution, and 1 indicates that all variation is due to genetic factors.

Multiplying the strength of selection by the heritability gives the proportion of the trait change that can be attributed to genetic factors influenced by selection. This approach is grounded in quantitative genetics, providing a comprehensive understanding of how traits respond to selective pressures in a population. In conclusion, the response to selection is a dynamic process influenced by both the strength of selection and the heritability of the trait, reflecting the interplay between genetic and environmental factors in shaping the population's characteristics.

Answer 2

The response to selection of a trait is calculated by multiplying the strength of selection by the heritability of the trait. Heritability accounts for genetic variance observed in a population's phenotype (option 4).

Step-by-step explanation:

The response to selection of a trait can be calculated as represented in option 4, which is by multiplying the strength of selection by the heritability. Heritability is a measure of how much of the variability of a phenotypic trait in a population is due to genetic differences among individuals. When selection acts on a trait, the response to that selection is determined by these genetic variances.

Applying this knowledge, if we have a population where a particular trait is under selection, the change in the trait’s phenotype from one generation to the next (the response to selection) can be estimated by the product of the strength of the selection and the heritability. For instance, if the heritability of a trait like plant height is high, and we apply strong selection for increased height, the expected response will be a greater increase in average plant height in the next generation.

Hence, the answer is option 4.