Q79: Given below are two statements, one is labelled as Assertion... - Quantitative and Biometrical Genetics - Genetics & Plant Breeding - ICAR JRF/SRF 2024 | Agrigyan

• Assertion (A) is True: Linkage disequilibrium (LD), also known as gametic phase disequilibrium, is defined as the non-random association of alleles at different loci within a given population, such that haplotype frequencies deviate from the products of individual allele frequencies ($D = P_{AB} - p_A p_B \neq 0$).
• Reason (R) is True: Physical linkage between closely spaced loci strongly suppresses meiotic crossing over, significantly slowing down the decay of LD across generations and maintaining high levels of association between adjacent alleles.
• Explanation Relationship: While tight physical linkage preserves and elevates LD, it is not the conceptual definition of LD nor its sole evolutionary cause; LD is also generated by population stratification, founder effects, genetic drift, epistatic selection, and recent admixture. Hence, Reason (R) is a valid biological fact but does NOT serve as the primary explanation for the definition stated in Assertion (A).
• Conclusion: Both (A) and (R) are correct but (R) is NOT the correct explanation of (A) (Option 2).

Correct option: (2) Both (A) and (R) are correct but (R) is NOT the correct explanation of (A)