shannon(x)where $p_{i}$ is the frequency of the band presence at the ith marker within the population. This index gives more weight to the presence than to the absence of bands. This has no real biological support, although it might account for the occurrence of homoplasic absences of bands (Bonin et al., 2007)
Shannon, C. E. 1948. A mathematical theory of comunication. Bell System Technical Journal 27, 379-423.