Final answer:
Position effect variegation results from the inactivation of a gene due to its relocation into a heterochromatic region of the chromosome, leading to varied expression of traits. This can be observed in situations like the coat color patterns in tortoiseshell cats due to X-chromosome inactivation.
Step-by-step explanation:
The process responsible for position effect variegation is the inactivation of a gene due to its incorporation in a heterochromatic region of the chromosome. This phenomenon can occur when a gene that is usually located in a more euchromatic (and thus, active) part of the chromosome gets relocated to a heterochromatic (and thus, silenced or less active) region. For instance, in fruit flies, the rearrangement of chromosomes can cause some genes to be inactivated when they move closer to heterochromatin, this inactivation varies between different cells, leading to variegated expression of some traits. A classic example of this is seen in the inactivation of certain coat color genes in females of some mammalian species, such as the tortoiseshell cat, where random X-chromosome inactivation leads to patches of differently colored fur, each patch expressing the coat color of the active X chromosome.
Another scenario where changes in gene position can lead to functional consequences is during chromosomal aberrations like deletion, duplication, inversion, or translocation. These rearrangements might cause a gene to function differently than it would in its original location, leading to various phenotypes, depending on whether regulatory regions of gene expression are disrupted or if the structural integrity of the gene itself is maintained.