Final answer:
Hardy-Weinberg disequilibrium occurs due to genetic drift, natural selection, gene flow (immigration), and mutations. These factors can change allele frequencies in a population, deviating from the conditions assumed by Hardy-Weinberg equilibrium which includes a large population, random mating, and absence of mutations, gene flow, and natural selection.
Step-by-step explanation:
Hardy-Weinberg disequilibrium can arise from several factors, including genetic drift, natural selection, immigration (or gene flow), and mutation. Genetic drift refers to changes in allele frequencies due to random chance events, such as natural disasters or the random survival and reproduction of individuals. Natural selection occurs when certain traits provide a survival or reproductive advantage, leading to changes in allele frequencies over generations. Immigration (or gene flow) involves the movement of individuals (and their genetic material) from one population to another, potentially altering allele frequencies in the receiving population. Lastly, mutation introduces new genetic variations and may result in new alleles within the gene pool.
Instances that violate the conditions of the Hardy-Weinberg Equilibrium include non-random mating, a small population size, mutations, and non-zero net migration. The principle assumes a large population size, random mating, no mutations, no immigration or emigration, and no natural selection. When these conditions are not met, the population may experience shifts in allele frequencies over time.