Phenotypic consequences of transposable elements: reversion mutations

    The yellow background color is due to expression of the recessive c allele when the alternative C allele at the anthocyanin locus for purple pigment has been disrupted by insertion of a transposable Ds element. Subsequent transposition of the element out of the locus in individual cells results in restoration of C allele, and anthocyanin production. As the cells from each revertant mutation divide and grow, large, medium, or small anthocyanin spots (top, middle, and bottom rows, respectively) result from transposition during early, middle, or late development.

HOMEWORK: Why are there small numbers of spots in the early revertants [top two rows], versus a larger numbers of spots in the late revertants?