Practice question

Genetic variation arises via mechanisms generating new alleles, new gene combinations, or new gene copies. Gene duplication creates extra copy of existing gene free to accumulate mutations and acquire novel functions, expanding gene families and proteome diversity, classic example globin genes. Mutation in mitochondrial DNA alters cytoplasmic variation but not nuclear diversity greatly. Differential expression based on parental imprinting changes phenotype not genotype. Loss of chromosome causes aneuploidy and usually reduces viable variation. Among listed options, duplication is well recognized major source of evolutionary innovation and increased heritable genomic variability across taxa.