Relationship between the total number of Pokey insertions outside rDNA estimated using qPCR and TE display. Empty symbols are diploids and solid symbols are polyploids. Empty orange circles: diploid hybrids with D. pulex mitochondrial haplotypes; solid orange circles: triploid hybrids with D. pulex mitochondrial haplotypes; solid square: D. middendorffiana; empty black triangles: diploid D. tenebrosa; solid black triangles: triploid D. tenebrosa; solid red triangle: introgressed D. tenebrosa with a D. pulex nuclear genome; solid green diamond filled with orange: triploid hybrids with D. pulicaria mitochondrial haplotypes. Thin lines represent lower (slope = 1 and y-intercept = 0) and upper limits for diploids (slope = 2 and y-intercept = 0) and triploids (slope = 3 and y-intercept = 0) of Pokey insertion number (see Methods). Thick lines are linear regressions estimated from the data.