Repetitive DNA sequences form a large portion of the genomes of eukaryotes. The major classes of tandem-repeat noncoding sequences are satellite DNA sequences, very highly repetitive sequences typically organized as large clusters of up to 100 megabases (Mb), in the heterochromatic regions of chromosomes; minisatellite sequences, moderately repetitive sequence arrays as long as ~15 base pairs (bp), found in euchromatic regions of the genomes of vertebrates, fungi, and plants; microsatellite sequences, arrays of short nucleotide repeats (2-5 bp), found in vertebrate, insect, and plant genomes (copy numbers are variable within a population, typically with mean array sizes of about 100 bp but with multiple array sizes classes distributed around the mean); and transposable elements (TEs), another class of moderately repetitive, mobile, and dispersed sequences (Charlesworth et al., 1994).