Self-Fertilization Without Genomic or Population Structuring in a Parasitic Tapeworm

The mode of reproduction and breeding system of a species major determinants of its genetic structure, and hence of its evolutionary trajectory. Self-fertilization, the fusion of male and female gametes from a single genetic entity, is an important component of the breeding system of many hermaphroditic flowering plants. Although conclusions differ with the assumptions of different population genetic models, the essential theoretical consequences of selfing are an increase in homozygosity, a reduction in genomic recombination, and the conversion of within-family to between-family genetic variation (Allard et al. 1968; Maruyama and Tachida 1992). These theoretical expectations have been largely confirmed by empirical studies in plants. Compared to outbreeders, predominantly selfing species usually show significant heterozygote deficiencies and linkage disequilibrium, and more genetic variation between than within populations (Loveless and Hamrick 1984; Heywood 1991).