Different indices are used for evaluating informativeness of a dominant marker such as PIC (polymorphism information content), He (genotypic gene diversity or expected heterozygosity), Hp (phenotypic gene diversity) or H' (Shannon’s index of diversity). These methods basically use the band frequency of different loci of a marker to calculate the informativeness. The dispersion rate of bands of a multilocus dominant marker across population that determines another aspect of the power of a marker in discriminating individuals has been argued in the present paper. The Simpson's diversity index is offered as a discriminatory index (D) to adjust the polymorphism information content (PIC) of the dominant markers. The proposed adjusted PIC (PICd = PIC D) has the potential to display both the polymorphism information content and the rate of band dispersion hereby increases the precision of comparison of the informativeness of different dominant markers. A plot of PIC against D index retains two important aspects (i.e. polymorphism content and discrimination power) of a dominant marker and thus would be useful to show polymorphic information content appropriately.
