Correct option is B
The correct answer is (b) because QTLs do not always have identical effects on a phenotypic trait in different environments. Environmental factors often interact with genetic factors, leading to genotype-by-environment interactions. This means that the expression of a quantitative trait (like height, yield, or disease resistance) can be affected differently in various environmental conditions, and the same QTL may have a different effect in different environments.
Explanation of Other Options:
(a) Loci responsible for a quantitative trait can show variations in their individual contributions to the trait.
This is correct. Different loci contribute to the expression of a quantitative trait in varying magnitudes, and this can lead to variation in phenotypic expression.(c) Recombinant Inbred Lines (RIL) populations used for QTL mapping are immortal.
This is also correct. RILs are created through repeated selfing and are considered immortal in the sense that they can be propagated indefinitely while maintaining their genetic composition, making them ideal for QTL mapping.(d) F₂:₃ families can measure both additive and dominant effects at specific QTL.
This is correct. F₂:₃ families allow for the estimation of both additive effects (the cumulative effects of alleles at a given locus) and dominant effects (when one allele masks the expression of another) at specific QTL.
Information Booster:
- Quantitative traits are typically controlled by multiple genes (QTLs), each contributing a small effect.
- Genotype-by-environment interactions can cause variability in how a trait is expressed across different environments.
- Recombinant Inbred Lines (RILs) are useful for QTL mapping because they are genetically stable and their alleles segregate predictably.
- Additive effects refer to the cumulative contribution of alleles at a QTL, whereas dominant effects occur when one allele masks the expression of another.
- F₂:₃ families allow researchers to measure both genetic effects and environmental interactions.
