Inequalities in the individual reproductive success of parasites.

Two simple methods of measuring the levels of inequality in reproductive success of different individuals in parasite populations are presented. These techniques are then applied to a number of sets of data for cestodes and acanthocephalans. The analysis suggests that both population density and host nutrition are important in determining the observed degree of inequality in reproductive success and body size. Cestodes, with a more flexible growth form, are shown to exhibit higher levels of inequality than acanthocephalans. The discussion outlines the evolutionary importance of considering variation in the reproductive success of different individuals.