Final answer:
Studying linkage disequilibrium helps identify loci affected by natural selection and is critical in GWAS for finding genetic markers associated with diseases, which aids in disease risk evaluation and therapeutic development.
Step-by-step explanation:
Studying linkage disequilibrium offers two practical reasons that are essential for understanding genetic variations and disease association. Firstly, it allows researchers to identify candidate loci of adaptive significance by evaluating how alleles at certain loci have frequencies diverging from expectations, assisting in pinpointing loci affected by natural selection.
Secondly, linkage disequilibrium is instrumental in genome-wide association studies (GWAS), where it can be used to find associations between specific genetic markers, like SNPs, and diseases. This can further lead to the identification of risk levels for various diseases as well as targets for developing new therapies. Understanding the role of linkage disequilibrium in these contexts is vital due to its capability to inform both evolutionary biology and medical genetics.