Table 2. The extension of Wright's F-statistic to represent the hierarchical population structure of obligate parasites of humans, exemplified in this paper with Wuchereria bancrofti (adapted from [24] and [34]).

Symbol	Definition
FIT	Correlation of alleles within individual worms relative to alleles drawn at random from the overall worm population (total deviation from the Hardy-Weinberg Equilibrium)
FIS	Correlation of alleles within individual worms relative to alleles drawn at random from the parasite infrapopulation (within host non-random mating)
	Correlation of parasite alleles within parasite infrapopulations relative to alleles drawn at random from parasites within the same village (parasite genetic differentiation between hosts within villages)
	Correlation of parasite alleles within a village relative to alleles drawn at random from the overall worm population (parasite genetic differentiation between villages)

The table includes a graphical representation of the different F-statistics.