Decremental copy regulation is a regulatory mechanism in which a molecule or gene's copy number decreases over time or under specific conditions. Copy number variation (CNV) is a genetic variation source that may contribute to phenotypic diversity and evolution . Genes in CNV regions are expressed at lower and more variable levels than genes mapped elsewhere, and CNVs not only influence the expression of copy number-varied genes but also have global effects on the transcriptome . Researchers have identified changes in DNA copy number, whether they affect specific genes or entire chromosomes, as the source of adaptive potential and the cause of disease and developmental abnormalities .