Final answer:
Besides selection on multilocus genotypes, genetic drift and gene flow are two mechanisms that can cause linkage disequilibrium. Genetic drift changes allele frequencies randomly, while gene flow introduces new alleles into a population, both disrupting allele associations.
Step-by-step explanation:
In addition to selection on multilocus genotypes, two other mechanisms that can create linkage disequilibrium include genetic drift and gene flow. Genetic drift refers to the random changes in allele frequencies that can cause allele associations different from those expected in a population mating at random, which can increase linkage disequilibrium if certain allele combinations survive by chance. Gene flow, or migration, also contributes to linkage disequilibrium when alleles from one population with different allele frequencies are introduced into another, thus disrupting local allelic associations. These mechanisms demonstrate how linkage disequilibrium can arise outside of direct selection pressures on certain genotypes, crucial for understanding microevolutionary processes and genetic variation.