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The mode of reproduction (sexual and/or asexual) and the mating system determine the patterns of gene transmission and genotype formation across generations. Schistosoma mansoni is a dioecious trematode that necessarily alternates sexual and asexual reproduction during its life cycle. In a previous study of the distribution of S. mansoni genetic variability within and between definitive host individuals, we noticed that deleting multilocus genotypes from each infrapopulation so as to keep only one copy of each multilocus genotype, seemed to have a substantial effect on FIS values. More precisely, female FIS increased when repeated genotypes were removed whereas no effect was observed on male FIS. This suggested that multilocus genotypes at high frequency tended to be more heterozygous. The aim of the present study is specifically to test and analyse this phenomenon. We demonstrate that the number of repetitions per clone correlates with individual heterozygosity. This effect is however, sex-specific: only female clone size correlates with heterozygosity. We discuss this phenomenon in relation to the heterozygosity-fitness relationship and the sex-specific response to inbreeding depression.

Original publication





Molecular ecology

Publication Date





2859 - 2864


GEMI, Equipe ESS, UMR-2724 CNRS-IRD, centre IRD, 911 avenue Agropolis, BP 64501, 34394 Montpellier Cedex 5, France.


Animals, Schistosoma mansoni, Linear Models, Monte Carlo Method, Genetics, Population, Sex Factors, Microsatellite Repeats, Reproduction, Heterozygote, Linkage Disequilibrium, Computer Simulation, Guadeloupe, Female, Male, Genetic Variation