Final answer:
Linkage disequilibrium in a randomly-mating population can stem from nonrandom mating due to mate choice or assortative mating, genetic drift resulting from chance events or the founder effect, and gene flow due to migration of individuals.
Step-by-step explanation:
Linkage disequilibrium in a randomly-mating population can be created through several mechanisms including nonrandom mating, genetic drift, and gene flow. Nonrandom mating can occur due to mate choice, where individuals select partners based on certain traits, like peahens preferring peacocks with larger tails, or due to assortative mating, which is the preference for partners with similar phenotypes.
Genetic drift refers to random changes in allele frequencies, which sometimes result from chance events such as natural disasters or in small populations where the founder effect might alter allele frequencies significantly.
Lastly, gene flow involves the migration of individuals between populations, introducing new alleles and changing allele frequencies. Physical location and the impacts of environmental variance are also factors to consider, as they can restrict mating opportunities and affect phenotypes, respectively.